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    25 December 2021, Volume 42 Issue 12 Previous Issue    Next Issue
    Pest Survey and Risk Assessment on Yongxing Island
    CHEN Qing, LIANG Xiao, WU Chunling, LIU Ying, CHEN Qian, HAN Zhiling, WU Mufeng
    2021, 42 (12):  3377-3387.  doi: 10.3969/j.issn.1000-2561.2021.12.001
    Abstract ( 73 )   HTML ( 9 )   PDF (1292KB) ( 38 )  

    The occurrence and damage of plant pests on Yongxing Island have not been reported so far. To effectively monitor the occurrence and damage of dangerous pests in Yongxing Island, this study conducted a systematic survey and risk assessment on all the pests of wild halophytes, landscape plants, salt-tolerant fruits and vegetables and sand-bander plants in Yongxing Island. The results of pest survey showed that there were 19 insects and mintes of 8 wild halophytes including 5 alien invasive pests and 11 world dangerous pests occurred and harmed seriously; 33 insects and mintes of 57 landscape plants including 9 alien invasive pests and 17 world dangerous pests occurred and harmed seriously; 36 insects and mintes of 31 salt-tolerant fruits and vegetables including 7 alien invasive pests and 20 world dangerous pests occurred and harmed seriously; 15 insects and mintes of 22 sand-bander plants including 5 alien invasive pests and 5 world dangerous pests occurred and harmed seriously. The results of risk assessment showed that Brontispa longissima, Paracoccus marginatus, Phenacoccus solenopsis were all high-risk pests in Yongxing Island and the R values of the three species were all 2.091, while Opisina arenosella, Diaspis boisduvalii, Dysmicoccu neobrevipes, Bemisia tabaci, Thrips palmi, Tetranychus urticae, Bactrocera cucuribitae and Liriomyza sativae were all moderate risk pests in Yongxing Island and the R values of the eight species were 1.99、1.97、1.93、1.87、1.87、1.87、1.82 and 1.79,respectively. These results were the first report on the occurrence and damage of plant pests in Yongxing Island, which will provide an important basic information support for the effective monitoring of biosafety in Yongxing Island.

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    Effects on Control Period and Frequency of Spodoptera frugiperda on Corn Yield
    LU Hui, TANG Jihong, LYU Baoqian, ZHANG Yongjun, LIU Wancai, SU Hao
    2021, 42 (12):  3388-3393.  doi: 10.3969/j.issn.1000-2561.2021.12.002
    Abstract ( 80 )   HTML ( 8 )   PDF (1202KB) ( 46 )  

    Spodoptera frugiperda (J. E. Smith) is an important migratory pest in the world. It has the characteristics of fast migratory speed, wide suitable area, strong reproduction ability, high degree of damage, and difficulty in prevention and control. In order to clarify the relationship between the control period and frequency of S. frugiperda and corn yield in the annual breeding area, emamectin benzoate was used to control S. frugiperda at seedling stage, small bell mouth stage, big bell mouth stage and tasseling stage respectively under field conditions. The main yield indexes were recorded at harvest stage, and the relationship between control period, control frequency, application interval and control effect and increase of yield was analyzed. The results showed that the effect of control treatments on the control effect of night was decreased with the delay of the control period, and the control effect at seedling stage (more than 90%) was better than that at bell mouth stage. The control effect decreased less than 83% after tasseling stage. The control effect after 2 times of application is more than 89%, and the difference between the treatments is not significant; the control effect after 3 times of application is all over 95%. In the seedling stage, small bell mouth stage, big bell mouth stage and tasseling stage, the control effect was the highest after 4 times of application, reaching 97.27%. The corn yield increased significantly with the increase of application times, and the highest corn yields were treated with 4 times of application, 3 times of application and 2 times of application at seedling + bell stage (both more than 10 t/hm2). The yields of 4 times, 3 times and 2 times at seedling + small bell stage of application were the highest, which were 10.96 t/hm2, 10.59 t/hm2 and 10.14 t/hm2, respectively, which were significantly higher than other treatments. The yield of seedling stage (7.29 t/hm2), small bell stage (8.04 t/hm2), big bell stage (7.56 t/hm2) and small bell + tasseling stage (9.08 t/hm2) was not significant, and they were all higher than tasseling stage (5.85 t/hm2). It indicated that the effect of pesticide application after the tasseling period was not obvious. The yield of all pesticide treatments was significantly higher than that of CK (4.29 t/hm2). Meanwhile, there was a quadratic function relationship between the number of application times, the interval period and the increase in corn yield. The largest increase in maize yield was observed by applying pesticides at intervals of 15-20 d. The highest yield increase was between 2 times and 4 times of application, and the treatments with the output increase more than 60% appeared. The highest yield increase was 63.43% (3 times of application), and the increasing value of yield was not obvious between 3 times and 4 times. Chemical control of S. frugiperda in the sweet corn of Hainan, the goal of high yield and high efficiency can be achieved by applying 2-3 times in the seedling stage, small bell mouth stage and big bell mouth stage.

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    Effect of Different Population Density of Spodoptera frugiperda on the Yield of Corn and Its Economic Threshold
    LIU Yanlong, LYU Baoqian, LU Hui, TANG Jihong, ZHANG Yongjun, ZHU Xiaoming
    2021, 42 (12):  3394-3401.  doi: 10.3969/j.issn.1000-2561.2021.12.003
    Abstract ( 53 )   HTML ( 6 )   PDF (1668KB) ( 55 )  

    Spodoptera frugiperda (J. E. Smith) can propagate annually in Hainan Province and has serious overlapping generations. It harms the production of fresh corn in Hainan Province and is difficult to control. In order to understand the effects of different population densities of S. frugiperda larvae on the yield of fresh corn field in Hainan Province, the third instar larvae of S. frugiperda were inoculated in the field to simulate natural hazards and study its economic threshold. The results showed that the regression equations of population density and total yield at seedling stage (4-6 leaves), bell stage (8-10 leaves) and heading stage (12-14 leaves) were as follows: y=-0.2508x+13.113, y=-0.1093x+ 12.721 and y=-0.0616x+ 12.447. The results showed that the population density which did not affect the yield was 5, 7, 9 larvae per 20 plants. The regression equations of population density and damage degree were as follows: y=0.06ln(x)+0.1258, y=0.0546ln(x)+0.1863, y=0.0589ln(x)+0.0275. The results showed that the damage degree of corn yield was 21.57%, 28.34% and 14.50%, and the economic threshold of each period was 6-8, 12-20, 19-24 larvaes per 20 plants, respectively. The results would provide a scientific basis for the precise control and reasonable pesticide reduction of S. frugiperda in corn fields of Hainan Province, which is of great significance to improve the economic benefits of control and protect the ecological environment.

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    Electroantennographic and Behavioral Responses of Invasive Insect Procontarinia robusta to Five Host Plant Volatiles
    CAI Hongjiao, TIAN Houjun, WEI Hui, LIN Shuo, CHEN Feng
    2021, 42 (12):  3402-3408.  doi: 10.3969/j.issn.1000-2561.2021.12.004
    Abstract ( 57 )   HTML ( 9 )   PDF (1677KB) ( 47 )  

    Mango midge (Procontarinia robusta) is an invasive agricultural pest with high reproductive potential and controlling larvae is much more difficult because insecticide hardly enters the plant gall tissue upon which the larvae are feeding. Plant volatiles are detected by olfactory receptor neurones in sensillae which are mostly on the insect antennae. In this study, the behavioral and electrophysiological responses of five mango leaf volatiles (α-pinene, 3-camphene, α-caryophyllene, isoterpinene and ethyl acetate) to gall midge adults were observed by the methods of electroantennogram (EAG) and Y- tube olfactometer. The five volatile substances caused significantly EAG responses on both female and male. The order of EAG response value was as follows: α-pinene> 3-camphene > α-carypohylene > terpinene > ethyl acetate. The EAG value of α-pinene treatments was significant higher (P<0.05) than that of the other treatments. Although the EAG response values of female midges to α-pinene, 3-camphene and α-caryophyllene were higher than those of males, there was no significant difference (P>0.05) between the male and female for individual substance. The order of attractive rate in the experiment of behavioral responses was as follows: 3-camphene > ethyl acetate > α-caryophyllene > α-pinene > terpinene. The highest attraction rate (74.20% ) was found in 3-camphene treatments, which was significantly higher (P<0.05) than that in α-pinene and isoterpinene treatments. The attraction rate of ethyl acetate was the second and reaching 66.07%. The highest repellent rate was found in isoterpineate treatments with 74.25%, which was significantly higher (P<0.05) than that in other volatiles. Meanwhile, the experiment showed a concentration threshold phenomenon. It meant that attractant or repellent response worked only within a specific concentration range and there was no response behavioral differences above or below the threshold concentration range. In our study, significant repellent effect was presented in the a-pinene treatment with the concentration range from 0.5 mL/L to 1.0 mL/L, but no significant difference was found in the rest concentration between repellent rate and attractive rate. Higher concentrations (1.0 mL/L and 2.0 mL/L) of α-caryophyllene displayed attractive function to midges compared with lower concentrations. The attractive rate of 3-camphene and a-carypohylene treatments to gall midges increased with the concentration rising. The experimental results would provide a theoretical basis for explaining the invasion mechanisms of gall midges. Our data is helpful to developing attractants or repellent in the aspect of monitoring technology and insect management.

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    The Influencing Factors and Mechanism of Wing Dimorphism in Aphid
    HE Yanbiao, LI Yicheng, ZHANG Min, LI Jia, LIU Jianhong, LIU Xiu, JIN Chenzhong
    2021, 42 (12):  3409-3415.  doi: 10.3969/j.issn.1000-2561.2021.12.005
    Abstract ( 68 )   HTML ( 6 )   PDF (1442KB) ( 57 )  

    Wing polymorphism is commonly observed in insects, for the sake of example, there are winged morph and wingless morph in aphids, the wingless morph lacks wings and is called apterous morph. Be of wings, the alate aphids can fly, successfully escape from wicked environment and find new habitat. Besides, the short reproduction cycle and large reproduction of apterous aphid are helpful to maintain a certain population. For aphid, wing dimorphism is an adaptive strategy in response to wicked environment. Both genetic and environmental factors are usually considered to affect the developmental outcomes of insect wing morphs. The wing polymorphism mainly affected by environment is called polyphenism. In this review, the ecological adaptive significance, influencing factors on determination of wing form, physiological and molecular mechanism of wing polymorphism were summarized. There are a few researches about wing dimorphism of Aphid, which partially confirmed that the wing type of pea aphid is controlled by an allele on the X chromosome. More researches identified that the environmental factors, including photoperiod, temperature, population density, symbiotic microorganisms, natural enemy, pesticides and antibiotics, may play an important role in this dimorphism. But in fact, these environmental factors often do not exist unilaterally. Juvenile hormone, ecdysone and other exogenous hormones are believed have interference effect on wing dimorphism. The appearance of crowding effect is probably resulted from the role of exogenous hormones.These factors may act prenatally, postnatally or both, depending on the species. For example, the middle instar nymphs treated by juvenile hormone probably develop to be supernumerary larva, not to be wingless adults. On the contrary, (E)-β-farnesene induced more winged morph offspring. Previous experimental injections of ecdysone or its analog resulted in a decreased production of winged offspring of Acyrthosiphon pisum. Furthermore, interfering with ecdysone signaling using an ecdysone receptor antagonist or knocking down the ecdysone receptor gene with RNAi resulted in an increased production of winged offspring. Molecular mechanism of wing type differentiation of aphids starts from the expressed differential genes or proteins of winged and wingless aphid of the same genotype.

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    Omics & Biotechnology
    Untargeted Metabolomics Analysis of Different Olive Varieties by UPLC-Q-orbitrap-MS Mass Spectrometry
    TANG Xuemei, ZHAO Xiaoli, GAO Yuwen, YE Qian, ZHU Fuwei, SU Lianshui, WAN Kai
    2021, 42 (12):  3416-3423.  doi: 10.3969/j.issn.1000-2561.2021.12.006
    Abstract ( 69 )   HTML ( 7 )   PDF (1752KB) ( 55 )  

    Olives (Olea europaea L.) are rich in biologically active substances, and the content of the components is closely related to olive varieties, processing and storage conditions. The chemical constituents of table olive were analyzed by UltraHigh Performance Liquid Chromatography-Quadrupole Orbitrap Mass Spectrometry (UPLC-Q-orbitrap- MS) combined with statistical analysis. A total of 47 significantly different metabolites were identified from the chromatograms of 2 olive varieties. The compounds included 9 kinds of amino acids, 20 kinds of flavonoids and polyphenols, 8 kinds of lipids, 3 kinds of organic acids, 2 kinds of coumarin compounds, and 5 kinds of other compounds. Juglalin, matairesinol, plantagoside, myricetin, taxifolin, PLPC, α-eleostearic acid and 18-β-glycyrrhetinic acid showed the highest values in Canarium pimela Koening. Ellagic acid, brervifolincaboxylic acid, gallic acid and its corresponding glucosides showed the highest values in Canarium album. The average content ratio of the substances in the two varieties is more than 30 times. The results showed that there were significant differences in the endogenous metabolites among different olive varieties and each had its own characteristics, which would provide data support for the future olive quality evaluation, rational utilization of olive resources and in-depth development of different olive products.

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    Expression Profiles Analysis of sHSPs in Hevea brasiliensis
    JI Xiangyun, YIN Han, REN Xiaoqing, LI Dejun, XIA Zhihui
    2021, 42 (12):  3424-3432.  doi: 10.3969/j.issn.1000-2561.2021.12.007
    Abstract ( 49 )   HTML ( 7 )   PDF (2207KB) ( 61 )  

    Small heat shock protein (sHSP) is a type of stress-inducing protein that not only participates in plant development but also responds to biotic and abiotic stresses. In this study, 12 sHSP gene family members of Hevea brasiliensis were obtained by analyzing transcriptome data. The results of bioinformatics analysis and expression profile analysis showed that all 12 sHSPs had α-crystallin conserved domains. The secondary structure prediction results showed that the 12 sHSPs were all composed of α-helix, β-turn, extended strand and a great quantity of random coils. RT-PCR analysis showed the expression of the 12 sHSP family genes in different tissues and developmental stages were significantly different, HbsHSP15.8, HbsHSP16.2, HbsHSP17.3, HbsHSP17.4, HbsHSP17.5b, HbsHSP18.2, HbsHSP18.3, HbsHSP22.5, HbsHSP22.6 and HbsHSP23.9 were highly expressed in latex, HbsHSP17.4 was highly expressed in bark, HbsHSP17.5a was highly expressed in tree stems, and HbsHSP25.8 was highly expressed in leaves. After ethephon treatment, the expression of the 12 sHSPs family genes showed an overall downward trend. The expression of the 12 sHSPs family genes in H. brasiliensis of different tapping panel dryness grades was also significantly different. The expression levels of HbsHSP15.8, HbsHSP17.4, HbsHSP17.5a, HbsHSP17.5b, HbsHSP18.2, HbsHSP18.3, HbsHSP22.6, HbsHSP23.9 and HbsHSP25.8 in diseased trees were significantly lower than that in healthy trees. The expression levels of HbsHSP16.2, HbsHSP17.3 and HbsHSP22.5 were significantly higher than that of healthy trees. It indicates that the sHSP family genes of H. brasiliensis may be involved in the response of rubber tree to biotic and abiotic stresses, and they may play an important role in ethylene pathway.

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    Analysis of Xa21 and Xa23 of indica Rice Varieties in Different Genetic Background to Broad Spectrum Bacterial Blight Pathogens
    YU Jianghui, LIU Tingchang, WENG Lüshui, LI Jinjiang, DENG Lihua
    2021, 42 (12):  3433-3442.  doi: 10.3969/j.issn.1000-2561.2021.12.008
    Abstract ( 50 )   HTML ( 8 )   PDF (3516KB) ( 53 )  

    The rice varieties of bacterial leaf blight resistance genes Xa21 or Xa23 were used as the donors, and the varieties without the genes as the receptor. By back crossing, composite crossing and other methods, combined with molecular marker-assisted selection (MAS), the varieties of Xa21 or Xa23, sister lines with or without Xa21 or Xa23 gene were inoculated with 7 widely used bacterial leaf blight pathogens, and the resistance of the varieties to the bacterial leaf blight was analyzed. The cumulative proportion of resistance (HR, R, MR) of the Xa21varieties was HNA1-4/PXO86 (84.62%)>YN24 (82.14%)>GD1358 (73.08)>PXO99 (67.86%)>GDA2 (63.33%)>FuJ (6.67%), and the varieties of Xa21 gene had no resistance to the bacterial leaf blight induced by FuJ, but for other pathogens, there were still 36.67%~15.38% of the varieties susceptible to diseases. The cumulative resistance (HR, R, MR) of the varieties of the Xa23 was over 76%, but there were still 23.02%~15.52% of the varieties that had no resistance to the 7 pathogens. Lesion length analysis, showed that the varieties of the Xa21 or Xa23 were resistant to different pathogen or the same pathogen. Different varieties had much variance. Lesion length analysis of of the7 bacterial leaf blight pathogens among the varieties of Xa21and Xa23 showed significant or extremely significant difference to GDA2 or HNA1-4 and other pathogens, and there was a extremely significant difference of YN24, GD1358 or PXO86 and other pathogens. The sister lines showed that bacterial leaf blight resistance of Xa21 or Xa23 was related to the donor of the varieties. Correlation of the varieties of Xa21 and parents showed extremely significant difference (R=0.5725 **), and there was a significant difference correlations of the varieties of Xa23 and parents (R=0.2212 *).

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    Transcriptome Sequencing Analysis of Leaf Vivipary in Water Lily
    SU Qun, TIAN Min, LI Chunniu, LI Xianmin, LU Jiashi, HUANG Zhanwen, LI Jiemei, BU Zhaoyang, WANG Hongyan
    2021, 42 (12):  3443-3450.  doi: 10.3969/j.issn.1000-2561.2021.12.009
    Abstract ( 61 )   HTML ( 8 )   PDF (2369KB) ( 73 )  

    Leaf vivipary in water lily (Nymphaea) is an important supplement to breeding, which plays an important role in the propagation and adaptability of species. Transcriptome sequencing technology was used to screen and explore genome-wide analysis of regulatory genes and metabolic pathways involved in leaf vivipary in water lily. This study would lay a foundation for further understanding the molecular mechanism of leaf viviparous development. Viviparous N. micrantha (X) and non-viviparous N. colorata (L) were selected as the experimental materials. By using RNA-Seq technology, four stages of leaf development of the leaf stalk and stem and stem join were tested and analyzed using a series of bioinformatics analysis. The result showed that 34 909 (48.65%) DEGs were up-regulated and 36 850 (51.35%) DEGs were down-regulated. DEGs analysis showed that up-regulated genes and down-regulated genes both increased with the leaves development of N. micrantha amd N. colorata. GO and KEGG enrichment analysis of L1-vs-X1 and L4-vs-X4 stage showed that DEGs were mainly enriched in plasmalemma, cytomembrane and extracellular domain cytoderm associated with metabolic process, biosynthesis and stimulus response. Pathway metabolism pathways indicated that DEGs were mainly involved in plant hormone signal transduction, phenylpropanoid biosynthesis, amino acids metabolism, flavonoid biosynthesis, glycerolipid metabolism and cell cycle and other processes. Four transcription factors potentially involved in leaf viviparous development of water lily were cloned based on DEGs analysis.

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    Functional Verification of Tomato Steroidal Glycoalkaloids Synthetase SlERT1b Gene and Its Transcriptional Regulation
    LI Han, SHI Yunxia, YUAN Honglun, LIU Xianqing, LUO Jie
    2021, 42 (12):  3451-3461.  doi: 10.3969/j.issn.1000-2561.2021.12.010
    Abstract ( 63 )   HTML ( 8 )   PDF (4381KB) ( 46 )  

    The steroidal glycoalkaloids in green tomatoes mainly exist in the form of α-tomatine, which gives tomatoes bitter taste and are not suitable for consumption. During the fruit ripening process, α-tomatine will generate esculeoside a through a series of enzymatic reactions, which makes fruits eatable. But the metabolic pathway has not been completely elucidated. In the previous research, we identified a glycosyltransferase SlERT1b which is involved in this metabolic pathway. In the study, the function of SlERT1b was studied by a tomato genetic transformation experiment. The steroidal glycoalkaloids were detected by LC-MS to verify the role in the metabolic pathway as a glycosyltransferase. Furthermore, the application of exogenous ethylene and ethylene inhibitors 1-MCP could regulate SlERT1b and affect the synthesis of steroidal glycoalkaloids. In addition, we identified the transcription factors SlJERF1 and SlAREB2 which can regulate the expression of SlERT1b. This research provide theoretical basis for the tomato genetic breeding.

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    Cloning and Genetic Transformation of Sugarcane Pokkah Boeng Fusarium sacchari CYP51 Gene
    ZHOU Yuming, HUANG Zhen, DUAN Zhenzhen, LI Huixue, BAO Yixue, ZHANG Muqing, YAO Wei
    2021, 42 (12):  3462-3470.  doi: 10.3969/j.issn.1000-2561.2021.12.011
    Abstract ( 88 )   HTML ( 8 )   PDF (10435KB) ( 70 )  

    CYP51 is a very important enzyme for the biosynthesis of biological cell membrane, and plays a very important role in drug resistance, pathogenicity, growth and reproduction of pathogens. The interference with expression of CYP51 gene in fungi can prevent its normal growth and significantly reduce its pathogenicity. In this study, the full length of FsCYP51 gene and CDS were cloned by designing specific primers based on the genome sequencing data of Fusarium sacchari. Bioinformatics analysis showed that the total length of the gene was 1947 bp, and the coding region consisted of two introns and three exons. The total length of CDS was 1554 bp, encoding 517 amino acids. The theoretical relative molecular weight of the coding protein was 58.61 kDa. The secondary structure of the encoded protein was mainly composed of α-helix and random coils, and it had a typical conserved domain CYP51. Its subcellular localization was predicted in the cell membrane and there were two transmembrane regions. Phylogenetic analysis showed that the FsCYP51 gene belonged to the CYP51C class, and was closely related to the CYP51C gene of F. verticillioides. At the same time, according to the full length of the gene and CDS, the polyvalent HIGS plant expression vector was constructed, and transformed into sugarcane by particle bombardment,which would lay a foundation for the study of function of FsCYP51 gene and the creation of transgenic sugarcane resistant to Pokkah boeng disease.

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    Omics & Biotechnology
    Cloning and Expression Pattern Analysis of DlTRF2-like in Longan
    LI Haoran, ZHANG Shuwei, WANG Jinying, HUANG Xiaoxiong, PENG Hongxiang, XU Jiongzhi, PAN Jiechun, ZHU Jianhua, TAN Chunlu, LI Ping, DING Feng
    2021, 42 (12):  3471-3476.  doi: 10.3969/j.issn.1000-2561.2021.12.012
    Abstract ( 57 )   HTML ( 7 )   PDF (2468KB) ( 44 )  

    The TRF2-like gene of MYB-related family was cloned from the mature leaves of longan and named DLTRF2-like. Bioinformatics and the expression pattern of DLTRF2-like were analyzed. DLTRF2-like gene belongs to the TRF-like subfamily of MYB-related family, with an ORF length of 909 bp, encoding a protein of 302 amino acids which was predicted to be located in the nucleus. Evolution analysis of homologous genes indicated that DLTRF2-like was most closely related to PvTRF2-like in Pistacia vera L. The expression pattern of DLTRF2-like in different tissues and leaves treated by ethephon and paclobutrazol was analyzed by real-time quantitative PCR. The results showed that DLTRF2-like was expressed in all the samples, and the highest expression level was found in flower buds. The expression level of DLTRF2-like gene in the leaves treated by ethephon and paclobutrazol was significantly higher than that of the control. The results indicated that DLTRF2-like might response to ethephon and paclobutrazol signal to promote the flowering of longan.

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    Identification and Expression Analysis in the Process of Flower Formation of Dof Gene Family in Sweet Orange (Citrus sinensis)
    YANG Jie, CHEN Rong, HU Wenjuan, WU Qiaoling, TONG Xiaonan, LI Xingtao
    2021, 42 (12):  3477-3485.  doi: 10.3969/j.issn.1000-2561.2021.12.013
    Abstract ( 59 )   HTML ( 8 )   PDF (3522KB) ( 57 )  

    The DNA binding with one zine figer proteins (Dof) in Citrus Sinensis was identified by bioinformatics, and the evolution model and expression pattern were analyzed. Used the recently released upland C. Sinensis genomic data, Dof genes in C. Sinensis were identified by bioinformatic methods. The chromosomal localization, physicochemical properties, sequence characteristics, phylogeny, cis-acting elements and expression profile of Dof genes in C. Sinensis were systematically analyzed. We identified 24 Dof genes which were distributed on 8 chromosomes. The phylogenetic-tree was clustered into 9 subgroups, and CsDof genes were divided into A, B1, B2, C1, C2.1, C2.2, D1 and D2 subgroups. The promoter region of CsDof genes contained a large number of light-responsive and hormone-responsive elements. The expression pattern of CsDof genes was different in buds and leaves of two sweet orange varieties by quantitative real-time PCR (qRT-PCR). The expression of CsDof6, CsDof11, CsDof13, CsDof17 and CsDof21 in ‘Newhall’ cultivars was higher than that in buds and leaves of ‘Gannan Zao’ cultivars, while that of CsDof19 and CsDof23 in ‘Gannan Zao’ cultivars was higher than that in buds and leaves of ‘Newhall’ cultivars. The CsDof genes had obvious specificity of variety expression in sweet orange at different flowering stages, it suggesting CsDof genes played an important role in the regulation of flowering time. The results would provide references for clarifying the functions of CsDof gene family in the regulation of flowering stage.

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    Application of Brassinolide in the Rapid Propagation of Sugarcane Tissue Culture
    ZHANG Ya, GU Minghua, ZHU Kezhen, LIANG Qiongyue, GONG Yinhua, HE Bing, HE Lishan
    2021, 42 (12):  3486-3491.  doi: 10.3969/j.issn.1000-2561.2021.12.014
    Abstract ( 53 )   HTML ( 8 )   PDF (3507KB) ( 44 )  

    Based on two tissue culture and rapid propagation systems of “plant organ de novo regeneration” and “somatic embryo regeneration”, six combinations of medium were designed by adding appropriate concentration of 2,4-epibrassinolide into the basic medium to explore the effects of brassinolide (BL) on sugarcane tissue culture. The morphological characteristics of different induction stages, including adventitious root induction, callus induction and seedling induction, were analyzed. The content changes of endogenous plant hormones (brassinolide, zeatin riboside, indole 3 acetic acid, abscisic acid) were determined. The feasibility of brassinolide application in sugarcane tissue culture and rapid propagation was discussed. The combination of adventitious root medium MS+0.2 mg/L 2.4-D+0.2 mg/L LFS and seedling medium MS + 0.5 mg/L KT+(0.2 mg/L IBA / 0.2 mg/L 2,4-EBL)+ 300 mg/L Pro was the better scheme for sugarcane tissue culture and rapid propagation. Brassinolide could be used in tissue culture and rapid propagation of sugarcane. The regeneration time of somatic embryo was better than that of callus, which could be shortened to 32 days.

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    Molecular Cloning and Analysis of CpDHN1, a Gene in Response to Drought Stress in Papaya (Carica papaya L.)
    GUO Jingyuan, ZOU Zhi, KONG Hua, HE Pingping, GUO Anping
    2021, 42 (12):  3492-3499.  doi: 10.3969/j.issn.1000-2561.2021.12.015
    Abstract ( 60 )   HTML ( 8 )   PDF (3325KB) ( 54 )  

    Papaya (Carica papaya L.), which belongs to the Carica genus within the Caricaceae family, is a popular tropical fruit with high nutritional value that are widely cultivated in tropical and subtropical areas. As a typical tropical crop that fruits through the whole year, papaya is vulnerable to abiotic stresses such as cold and drought. Presently, there are few reports on stress resistance of papaya, and main studies focus on the virus disease which leads to the extinction of papaya production. Dehydrin, also known as type two late embryogenesis abundant protein, is a class of natural non-structural proteins with high hydrophilicity, rich in glycine, and low complexity. It has attracted extensive attention because it is highly related to the ability of plants to resist abiotic stresses. In order to solve the regional limitation of papaya cultivatation and further improve the fruit quality and yield, it is of importance to screen and characterize key genes involved in abiotic stress response. Based on a de novo assembled transcript, a 636 bp open reading frame of a gene that was denoted as CpDHN1 was isolated from the leaf tissue of cultivar ‘Tainong No. 2’ using RT-PCR. Bioinformatic analysis showed that CpDHN1 putatively encodes 211 amino acids, which was predicted to target the nuclear and have a theoretical molecular weight (Mw) of 24.09 kDa, an isolectric point (pI) of 5.05, a GRAVY value of -1.584, and an instability index of 66.51, implying its unstable, hydrophilic, and nuclear-targeted characteristics. CpDHN1 is rich in glutamate, lysine and serine, and it can be categorized as the SKn-type dehydrin with two conserved K-segments and one S-segment. CpDHN1 doesn’t contain any transmembrane helix and its secondary structure is mainly composed of α-helixes. Homology analysis showed that CpDHN1 shares the highest sequence similarity with AtLEA4 (i.e. 46.8%), while the sequence similarity with another reported dehydrin (i.e. CpDHN) is just 19.4%. Expression analysis revealed that CpDHN1 was expressed in all tested tissues, i.e. root, leaf, and sap, and the transcript level was significantly regulated by drought stress. Moreover, its prokaryotic expression vector was also successfully constructed, and SDS-PAGE showed that CpDHN1 could efficiently accumulate in Escherichia coli. It accumulated a small amount at the theoretical molecular weight of 40 kDa, but a large amount at 55 kDa, supporting that CpDHN1 is an intrinsically unstructured protein. These results lay a solid foundation for further functional analysis and utilization of this special gene in papaya and other species.

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    Cross-compatibility among Three Wild Banana Species and Various Cultivars
    LI Weiming, HU Huigang, HU Yulin, DUAN Yajie, CHEN Jingjing, XIE Jianghui, WANG Wenhua
    2021, 42 (12):  3500-3507.  doi: 10.3969/j.issn.1000-2561.2021.12.016
    Abstract ( 52 )   HTML ( 7 )   PDF (1808KB) ( 38 )  

    The majority of banana cultivars are male sterility, which give rise to the lack of banana diversity and varieties recession in resistance. The cross-breeding deserves a good strategy for the improvement of genetic diversity and agronomic traits. In order to find out the genotypes qualified as male and female parents, we conducted large-scale cross-breeding among three wild relatives and various cultivars. The pollen activity was examined for the wild relatives of Musa acuminata ssp. malaccensis (AA), Musa balbisiana (BB) and Musa cheesmani. The pollen staining rate (> 63%) was high for all species. Popular cultivars Musa AAA, Musa AAB, Musa ABB including Pisang Awark and Da jiao, Musa AA were cross-bred with the wild relatives (male). The seed set, seed generation and seedling morphological trait were observed to evaluate the cross-compatibility of different combinations. Only Musa ABB could set seeds. The seed set, seed generation and seedling morphological trait for M. balbisiana were much better. M. cheesmani was compatible with some cultivars. The study would provide reference dataset for worldwide banana researchers.

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    Plant Cultivation, Physiology & Biochemistry
    Dynamics of Nitrogen, Phosphorus and Potassium Nutrients in the Leaves of ‘Malaysia No. 1’ Jackfruit
    ZHANG Feng, SU Lanxi, BAI Tingyu, WU Gang, TAN Lehe, LI Wen, GUO Rui, ZHAO Zhengjie
    2021, 42 (12):  3508-3513.  doi: 10.3969/j.issn.1000-2561.2021.12.017
    Abstract ( 60 )   HTML ( 5 )   PDF (1402KB) ( 47 )  

    The annual changes of nitrogen, phosphorus and potassium in the leaves of ‘Malaysia No. 1’ jackfruit in three locations in Hainan were similar. The annual average content of elements was N > K > P. According to the investigation of the growth period in actual production, the growth cycle of jackfruit is roughly divided into two batches and three stages, the first batch of tree growing stage (November to December), the first batch of flower stage (January to February), the first batch of fruit stage (March to April), the second batch of tree growing stage (May to June), the second batch of flower stage (July to August), the second batch of fruit stage (September to October). During the growth cycle, the annual variation of nitrogen content showed a trend of “N” shape. From January to April, the phosphorus content increased first and then decreased, and then increased slowly. The variation trend of potassium content was similar to that of nitrogen content, but the variation trend of potassium content was not as obvious as that of nitrogen content. The optimum range of abundant elements in the leaves of jackfruit was N 21.03-22.15 g/kg, P 2.86-3.40 g/kg, K 13.49- 14.47 g/kg, respectively. The growth and development of jackfruit require more nitrogen and potassium elements, especially in the flower and fruit stages, so attention should be paid to increasing the application of nitrogen and potassium fertilizer, and sufficient phosphate fertilizer should be applied at the tree growing stage.

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    Transport of Inorganic Nitrogen in the Soil of Rubber Plantation under Different Nitrogen Application Rates at Early Stage
    WANG Shuai, ZHANG Yongfa, REN Changqi, LUO Xuehua, XUE Xinxin, ZHAO Chunmei, MA Junyao, GENG Jianmei, WANG Wenbin
    2021, 42 (12):  3514-3520.  doi: 10.3969/j.issn.1000-2561.2021.12.018
    Abstract ( 49 )   HTML ( 3 )   PDF (1486KB) ( 36 )  

    The form and content of inorganic nitrogen in rubber plantation showed seasonal dynamic changes. In this study, field experiments with different nitrogen application rates were conducted to study the transportation of nitrogen in rubber plantation after fertilization at the early stage. The transportation characteristics of mineral nitrogen were different with different nitrogen application rates, but vertical transportation was the main pathway. The horizontal transportation of ammonium nitrogen and nitrate nitrogen in soil at different levels was mainly within 30 cm. There was obvious downward transportation of ammonium and nitrate nitrogen in the soil under different fertilization treatments. Ammonium nitrogen was mainly transported to the depth of 40-60 cm, and the content of ammonium nitrogen reached 209.43 mg/kg in conventional fertilization and 133.32 mg/kg in 20% reduced fertilization, respectively. Nitrate nitrogen was mainly transported to 20-40 cm depth, and the nitrate nitrogen content of conventional and 20% reduced fertilization was 127.21 mg/kg and 114.29 mg/kg, respectively. There were also significant differences in the downward transportation of inorganic nitrogen under different fertilization treatments. The inorganic nitrogen under 40% reduced fertilization was lower in the deep soil than that under traditional fertilization and 20% reduced fertilization, which indicated further reducing of N leaching loss. The main form of soil mineral nitrogen under different fertilization treatments was ammonium nitrogen. Fertilization increased the proportion of nitrate nitrogen, which may be related to nitrogen fertilizer input and soil pH.

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    Physiological Characteristics of Stress Response Induced by Physical Injury in Aquilaria sinensis
    ZHANG Peng, XU Anwei, YANG Guangda, XIAO Jiajie, LI Xiaofei, XU Daping, CUI Zhiyi
    2021, 42 (12):  3521-3528.  doi: 10.3969/j.issn.1000-2561.2021.12.019
    Abstract ( 39 )   HTML ( 4 )   PDF (1977KB) ( 51 )  

    Mechanical drilling treatment was implemented for three-year-old common Aquilaria sinensis and easily induced agarwood A. Sinensis to analyze the characteristics of stress response of A. sinensis induced by physical injury. The changes of hormone content, antioxidant enzyme activity, phenolic and terpenoid defense substances, and terpenoid precursor acetyl-CoA content were analyzed before and after mechanical injury. The stress response characteristics of two kinds of A. sinensis after physical injury were compared. The contents of jasmonic acid, salicylic acid and ethylene of common Aquilaria sinensis and easily induced agarwood A. sinensis increased significantly after mechanical damage. Except for ascorbate oxidase, the activities of the other five antioxidant enzymes enhanced significantly. The contents of total phenols and total terpenes were increased by 15.31% and 9.04% in common A. sinensis, and 24.63% and 15.08% in easily induced agarwood A. sinensis respectively. Acetyl-CoA also increased significantly in both kinds of A. sinensis. Among them, the increments of jasmonic acid and ethylene precursor contents were significantly higher in easily induced agarwood A. sinensis than those in common A. sinensis. The activity changes of superoxide dismutase, catalase and peroxidase of easily induced agarwood A. sinensis were 1.63, 1.60 and 1.55 times of common A. sinensis respectively. The increments of total phenols and terpenes of easily induced agarwood A. sinensis were significantly higher than that of common A. sinensis. The increment of acetyl-CoA in easily induced agarwood A. sinensis was 1.74 times higher than that in common A. sinensis. In conclusion, stress response substances of A. sinensis increased after mechanical injury, and most indexs of them were significantly higher in easily induced agarwood A. sinensis than those in common A. sinensis. It was suggested that the stress response of easily induced agarwood Aquilaria sinensis was stronger than common Aquilaria sinensis. Jasmonic acid, ethylene, superoxide dismutase, catalase, peroxidase, total phenols, total terpenes and acetyl-CoA were significantly different between the two kinds of Aquilaria sinensis, which could be used as effective physiological indexes for rapid identification of easily induced agarwood Aquilaria sinensis.

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    Plant Cultivation, Physiology & Biochemistry
    Evaluation of Amino Acid Characteristics and Nutrient Composition of Six Edible Fungi Cultivated by Cinnamon
    HUANG Qinghua, WANG Lining, ZHANG Liulian, WANG Qingfu, LIANG Lei, CHEN Junjie, LIN Ju
    2021, 42 (12):  3529-3536.  doi: 10.3969/j.issn.1000-2561.2021.12.020
    Abstract ( 52 )   HTML ( 6 )   PDF (1546KB) ( 53 )  

    The nutrient composition and amino acid composition were determined to evaluate the nutritional characteristics of 6 edible fungi (Pleurotus citrinopileatus, P. geesteranus, P. eryngii, Oudemansiella raphanipes, Pholiota adiposa, Hericium erinaceus) cultivated by cinnamon. Then the nutritional value of protein was evaluated and classified by principal component analysis, protein nutritional value evaluation and cluster analysis. The contents of dietary fiber, polysaccharide and protein in the fungi ranged from 24%~46%, 4~15 mg/g and 19%~43%, respectively. The principal component analysis results of essential amino acids showed that PC1 and PC2 explained a total of 92.46% difference. Threonine, leucine, isoleucine, phenylalanine and the valine were determined PC1, while the lysine determined PC2. Amino acid score showed that the methionine and cysteine (Met+Cys) contents in the fungi were excessive. Compared with the other 5 fungi, the excess content of P. geesteranus was less, which was similar to the WHO/FAO model value. The results of amino acids clustering analysis among the fungi cultivated by cinnamon were related to the Met+Cys content. P. adiposa and P. citrinopileatus had the closest clustering distance, while that of P. geesteranus was relatively long and was significantly different from the other 5 fungi. In conclusion, cinnamon cultivated edible fungi were the ideal protein source because of rich content and relatively complete variety of amino acids. However, it still needs to be matched with other diets to achieve a balanced supply of amino acids in human body due to the high Met+Cys content.

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    Effects of Foliar Calcium and Magnesium Fertilizer on Citric Acid Accumulation of ‘Feizixiao’ Litchi Fruit
    LIAO Haizhi, LIN Xiaokai, YANG Chengkun, DU Jingjia, PENG Junjie, ZHOU Kaibing
    2021, 42 (12):  3537-3544.  doi: 10.3969/j.issn.1000-2561.2021.12.021
    Abstract ( 47 )   HTML ( 1 )   PDF (1723KB) ( 41 )  

    The effects of spraying foliar nutrition of calcium and magnesium on the citric acid accumulation of ‘Feizixiao’ litchi fruit was explored in this paper. During the period of fruit development, the fruits which were sprayed 0.3% magnesium chloride (Mg), 0.3% calcium chloride (Ca) and the mixture (Ca+Mg), and water (CK) as the experimental materials to measure the contents of water-soluble calcium, water-soluble magnesium and citric acid, enzymes activities of related citric acid in fruit flesh, and made the multivariate linear correlation analysis. The content of citric acid showed an M-shaped trend. Ca and Ca+Mg treatments promoted the accumulation of citric acid, while Mg treatment promoted and then inhibited the accumulation of citric acid. The activities of ICL in CK and CS in Ca+Mg treatment were positively correlated with the content of citric acid,, respectively, however, the activity of IDH in Ca+Mg treatment was negatively correlated with it. The content of water-soluble calcium in the flesh showed an increased trend, and the content of water-soluble magnesium showed the trend of “increased, decreased, increased, decreased”. The water-soluble calcium could inhibit the activities of PEPC, ACO and CS, and the water-soluble calcium in CK could improve the activities of PEPC enzymes. The water-soluble magnesium could increase the activities of ICL and PEPC, and could inhibit the activities of ACO, CS, IDH. In conclusion, spraying the foliar nutrition of calcium and magnesium could affect the contents of water soluble calcium and magnesium, and could change the linear correlation between the contents of water soluble calcium, magnesium and the activities of related enzymes of citric acid. Different treatments affected the accumulation of citric acid in pulp and caused the change the total acid content in pulp. Ca and Ca+Mg treatment may inhibit pulp respiration through the accumulation of more citric acid to reduce the loss of sugar in pulp.

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    Effects of Magnesium Nutrition on the Growth and Development of Momordica charantia and Its Physiological Metabolism
    YOU Chuihuai, SUN Qinghui, CHEN Sheng, KE Yan, LIN Xinping, SHI Mutian
    2021, 42 (12):  3545-3552.  doi: 10.3969/j.issn.1000-2561.2021.12.022
    Abstract ( 71 )   HTML ( 4 )   PDF (1866KB) ( 60 )  

    A variety ‘Cuiyu’ of Momordica charantia was planted by sand culture and treated with five magnesium concentrations (0, 20, 40, 80, 160 mg/L). The effects of magnesium nutrition on the growth characteristics (leaf and root morphology, photosynthetic pigment content, carbon and nitrogen metabolism, and biomass accumulation) and physiological response (osmoregulation, membrane damage and antioxidation) of M. charantia were investigated. Application of 20-80 mg/L magnesium reduced leaf membrane damage, increased the contents of soluble sugar, soluble protein, photosynthetic pigment and glutathione (GSH), and enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and monodehydroascorbate reductase (DHAR). But the contents of M. charantia leaf malondialdehyde (MDA), proline (Pro) and hydrogen peroxide (H2O2), the production rate of superoxide anion (O2 -), and cell membrane permeability were all reduced, while their root vitality, photosynthesis and biomass accumulation were promoted. Among them, 40 mg/L magnesium treatment had the most obvious synergistic effect on the growth and development of M. charantia. However, under the stresses of magnesium deficiency (0 mg/L) and excess (160 mg/L), the membrane lipid peroxidation damage occurred in the M. charantia, and the main roots were shortened, the lateral roots decreased, the growth of the above ground and underground parts was significantly inhibited, and magnesium deficiency had a stronger inhibitory effect on M. charantia than excessive magnesium. To sum up, the results indicated that magnesium deficiency and excess inhibited the growth of M. charantia. The appropriate application of magnesium could effectively improve the physiological activity, enhance the stress resistance and promote the growth of M. charantia. And 40 mg/L magnesium was the most suitable concentration of magnesium for the cultivation of M. charantia.

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    Effect of Increasing Organic Fertilizer on the Yield and Quality of Psidium guajava
    ZHANG Chaokun, HUANG Wanli, KANG Shicheng
    2021, 42 (12):  3553-3558.  doi: 10.3969/j.issn.1000-2561.2021.12.023
    Abstract ( 58 )   HTML ( 4 )   PDF (1305KB) ( 48 )  

    The study was aimed to explore the effects of adding organic fertilizers on the yield and quality of two harvests of guava fruits a year with chemical fertilizers, and to provide a basis for scientific fertilization of guava. The effects on the appearance, yield, quality and economic benefits of guava fruit of ‘Hongxiang No. 1’ by the application of chemical fertilizer (CK), CK + organic fertilizer 2.5 kg/plant, CK + organic fertilizer 5.0 kg/plant, CK + organic fertilizer 7.5 kg/plant and CK + organic fertilizer 10.0 kg/plant were studied. The combined application of organic fertilizer increased the quality of fruit, increased the longitudinal diameter, transversed diameter and fruit shape index, improved the appearance of the fruit, increased the yield, and at the same time increased the contents of soluble solids, Vc, soluble sugar and reducing sugar, reduced the content of titratable acid, improved economic benefits. Among them, the effect of applying 7.5 kg of organic fertilizer per plant is the best. The quality of the first and second harvest fruit, the vertical and horizontal diameter of the fruit increased by 32.48% and 20.77%, 31.70% and 33.97%, respectively, the content of soluble solids, Vc, soluble sugar and reducing sugar increased by 14.95% and 25.76%, 56.58% and 57.55%, 56.93% and 53.23%, 40.87% and 50.54%, respectively, the the content of titratable acid content reduced by 25.00% and 19.35%, and the total profit increased by 55.46% over CK.

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    Plant Protection
    Effects of Chlorosis on Main Agronomic Traits and Endogenous Hormones of Ratoon Sugarcane
    LUO Ting, DENG Yuchi, QIU Lihang, CHEN Rongfa, FAN Yegeng, ZHOU Huiwen, YAN Haifeng, HUANG Xing, ZHOU Zhongfeng, WU Jianming
    2021, 42 (12):  3559-3565.  doi: 10.3969/j.issn.1000-2561.2021.12.024
    Abstract ( 37 )   HTML ( 0 )   PDF (3455KB) ( 34 )  

    The hormone level, chlorophyll index, tiller number and plant height were analyzed to investigate the effects of chlorosis on the main agronomic traits and endogenous hormone changes of ratoon sugarcane. After 40 days of growth, the chlorophyll index of the chlorosis plant reached 40, equal to the chlorophyll index of the normal plant at the time of emergence, and it took 62 days for the chlorosis plant to turn green and get normal. The increment of plant height, leaf, internode and tiller number of normal plant was 1285%, 371%, 860% and 1650% of that of chlorosis plants, respectively. And there were significant differences between normal and chlorosis plants at 5 determination periods. The contents of gibberellin, auxin and cytokinin were 17.3% and 12.9% higher than those of normal strains, respectively, which were significantly different from normal strains. The contents of zeatin, abscisic acid and ethylene in chlorosis plants increased by 54.5%, 195.5% and 47.4%, respectively, which were significantly different contrast to normal plants. This study initially revealed the effects of chlorosis on the main agronomic traits and endogenous hormones of sugarcane, and would provide some knowledge for the prevention and control of chlorosis in ratoon sugarcane.

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    Evaluation Method and Identification of Different Colored Zantedeschia Varieties to Soft Rot Pathogen Pcc
    ZHANG Qi, GUO Yanbing, LI Ziwei, WU Hongzhi
    2021, 42 (12):  3566-3573.  doi: 10.3969/j.issn.1000-2561.2021.12.025
    Abstract ( 35 )   HTML ( 1 )   PDF (2774KB) ( 37 )  

    The study was aimed to explore the suitable inoculation method of soft rot pathogen Pcc on the colored Zantedeschia spp., and identify the resistance of the varieties in the section Aestivae, which are called the colored Zantedeschia spp. to Pcc. Ten cultivars from the section Aestivae were used as the experimental materials to explore the suitable method for Pcc inoculation. Whole leaf and disk disc were used as the inoculation material in the identification in vitro, and main vein or lateral vein of the plants were compared for suitable inoculation site in the field identification in vivo. Disease incidence and disease index was observed at 12 h, 24 h and 36 h respectively after inoculation. After the suitable inoculation method and the best time of observing disease development were confirmed, 34 cultivars of colored Zantedeschia spp., including the 10 cultivars used in the first experiment were selected to identify the resistance to Pcc. The suitable material for inoculation in vitro was whole leaf, and the best observation time was 24 hours, main vein was better inoculation site than lateral vein for the plant in field, and the best observation time was 36 hours. There were 5 moderately resistant varieties, 11 susceptible varieties, and 18 highly susceptible varieties in the identification in vitro. There were 2 moderately resistant varieties, 17 susceptible varieties, and 15 highly susceptible varieties in the field identification in vivo. There were more moderately resistant varieties in the identification in vitro than that ones in vivo, which was in line with the situation of large-scale production in the field. The reason maybe it is easier to control the uniformity of materials inoculated and the consistency of environmental conditions in the identification in vitro than that in the field plant, so it is better to test the resistance of Zantedeschia spp. varieties to Pcc.

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    Synergistic Effect of Adding Spray Adjuvants on Spirotetramat and Bifenthrin for the Control of Phenacaspis dendrobii on Harba Dendrolii Nobilis
    LIU Ying, CHEN Qing, LIANG Xiao, WU Chunling
    2021, 42 (12):  3574-3580.  doi: 10.3969/j.issn.1000-2561.2021.12.026
    Abstract ( 41 )   HTML ( 0 )   PDF (1448KB) ( 36 )  

    To make clear the synergism and mechanisms of three spray adjuvants on spirotetramat and bifenthrin against Phenacaspis dendrobii, the influence of three spray adjuvants (fast penetrating agent T, organosilicon additive DA101 and vegetable oil auxiliaries HZS) on physical properties of pesticide liquid, the synergistic effects on indoor virulence and field control effect were investigated in this study. The results indicated that adding the three spray adjuvants could reduce the surface tension, contact angle and also increase the retention of pesticide liquid of spirotetramat 22.4% SC and bifenthrin 100 g/L EC. Spray adjuvants could increase the indoor virulence of spirotetramat and bifenthrin. Synergistic effect of adding fast penetrating agent T on spirotetramat and adding HZS on bifenthrin were better than that of the other two adjuvants and the synergism ratio was 34.4% and 24.3%, respectively. Field experiments showed that the addition of fast penetrating agent T had a good synergistic effect on spirotetramat for controlling P. dendrobii in different concentrations and the synergism ratio was between 8.2%-22.8%, as well as the synergism ratio of HZS to bifenthrin was between 10.6%-27.5%. So, adding spray adjuvants on spirotetramat and bifenthrin have an obvious synergistic effect for the control of P. dendrobii and this is suitable for popularization and application in production practice.

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    Suitability and Restrictive Environmental Factors of Hippotion velox in China
    LIU Bo, WANG Yenan, TANG Chao, LIU Li, MA Guangchang, PENG Zhengqiang, YAN Wei
    2021, 42 (12):  3581-3587.  doi: 10.3969/j.issn.1000-2561.2021.12.027
    Abstract ( 40 )   HTML ( 2 )   PDF (2793KB) ( 38 )  

    Hippotion velox is a migratory insect that damages Pisonia grandis. It occurs in many islands of China Paracel Islands. MaxEnt model was used to to clarify the potential suitable area and the main environmental factors of H. velox in China and to provide a theoretical basis for the early warning and prevention of the insect. An optimal model by adjusting the regularization multiplier and feature combination parameters was established. The environmental factors affecting the distribution of H. velox were evaluated using the jackknife method and the response curve of environmental variables. The potential suitable area of H. velox are distributed in Hainan, Taiwan, Guangdong, Guangxi, Yunnan, Guizhou, Hunan, Jiangxi, Fujian, Zhejiang, Anhui, Hubei, Sichuan, Chongqing, Tibet. The min temperature of the coldest month (bio06), the mean diurnal range (bio02) and the precipitation of warmest quarter (bio18) are the dominant environmental factors affecting the potential suitable area of H. velox. H. velox has a high risk in the South China Sea islands. It is recommended to establish an early warning and control system to to control the pest at a reasonable level.

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    Antifungal Effect of Silicon on Sporisorium scitamineum in vitro
    WANG Wenju, SUN Tingting, CEN Guangli, LOU Wenyue, CHEN Yanling, QUE Youxiong, YOU Chuihuai, SU Yachun
    2021, 42 (12):  3588-3597.  doi: 10.3969/j.issn.1000-2561.2021.12.028
    Abstract ( 47 )   HTML ( 3 )   PDF (7222KB) ( 58 )  

    Smut caused by Sporisorium scitamineum is the most important fungal disease in Saccharum spp. production. Silicon is a beneficial mineral element in plant growth, which can improve plant resistance to biotic and abiotic stresses. At present, the antifungal effect of exogenous silicon on S. scitamineum in vitro has not been reported. In this study, the spore germination, colony diameter and mycelium growth of the S. scitamineum were observed using sodium silicate (Na2SiO3) and potassium silicate (K2SiO3) to evaluate the antifungal effects of different silicon agents and pH on S. scitamineum in vitro. The spore germination of S. scitamineum was completely inhibited by 0.5-20.0 mmol/L Na2SiO3 and K2SiO3. The colony and hyphal growth of S. scitamineum were promoted by 1.0 mmol/L Na2SiO3, but was significantly inhibited by 10.0 mmol/L and 20.0 mmol/L Na2SiO3 and K2SiO3. The results suggested that Na2SiO3 and K2SiO3 could affect the growth of S. scitamineum, and high concentrations exhibited obvious antifungal effects. The spores could germinate at low pH (5.87-10.86), but the germination rate gradually decreased with the increase of pH. High pH (≥10.96) completely inhibited the spore germination. In addition, pH 9.40 and pH 11.57 significantly inhibited the colony growth. After adjusting pH to 6.0, low concentrations of Na2SiO3 (0-5.0 mmol/L) and K2SiO3 (0-3.5 mmol/L) had little effects on the spore germination, but high concentrations of Na2SiO3 (7.0-20.0 mmol/L) and K2SiO3 (5.0-20.0 mmol/L) significantly inhibited the spore germination. The results indicated that at the same pH level, the inhibition effect of K2SiO3 on the spore germination of S. scitamineum was better than that of Na2SiO3 and the corresponding pH treatment. This study would provide references for further pesticide effect test and control mechanism research on the resistance of sugarcane to smut.

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    Isolation and Identification of Endophytic Fungi from Allelopathic Rice and Analysis of Biological Effects of Their Fermentation Products
    CHEN Yihui, ZHANG Kuanchao, TENG Bin, ZHANG Chen, ZHANG Ying
    2021, 42 (12):  3598-3604.  doi: 10.3969/j.issn.1000-2561.2021.12.029
    Abstract ( 42 )   HTML ( 2 )   PDF (458KB) ( 46 )  

    Using allelopathic rice ‘PI312777’ ‘6173’ and ‘6180’ as the materials, 70 endophytic fungi were isolated from the roots, stems and leaves, and were further classified and identified by morphologic observation and rDNA ITS sequence analysis. To study the effects of fungal fermentation products on the morphological indexes such as germination rate, stem height and phenylalanine ammonia lyase, catalase and peroxidase changes, Rhodotorula mucilaginosa and Aspergillus tabiensis isolated from allelopathy rice ‘PI312777’ were used as the experimental strains and their fermentation broth of different concentrations were used to carry out MS semi-solid medium seedling experiment on non-allelopathy rice. The results showed that 17 isolates of endophytic fungi and 10 genera were identified through rDNA-ITS sequence analysis. Aspergillus, Penicillium and Fusarium were the dominant species in allelopathic rice with the relative isolate frequency 29.63%, 16.67% and 12.96%, respectively. Different concentrations of A. tabiensis fermentation broth all promoted the growth of rice seedlings, among which the 50 times diluted concentration treatment significantly improved plant height, root length and POD activity of rice seedlings compared with the control treatment. High concentration of R. mucilaginosa fungus fermentation broth improved PAL activity of rice. Under the symbiotic condition of barnyard grass and rice, A. stabiensis and R. mucilaginosa both had promoting effects on the growth of non-allelopathic rice. The finding of this study could provide useful guidance for the further application of allelopathic endophytes in rice production.

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    Post-harvest Treatment & Quality Safety
    Withering Technology of Different Light Quality to Increase Catechin Content in Fresh Tea Leaves
    LIN Yanyan, LIU Jianghong, DAI Qiuxiang, LI Zhihui, LIN Jinke
    2021, 42 (12):  3605-3616.  doi: 10.3969/j.issn.1000-2561.2021.12.030
    Abstract ( 34 )   HTML ( 1 )   PDF (9220KB) ( 31 )  

    In order to produce catechins-rich tea, this study explored different light quality wilting processes to increase the catechins content in fresh tea leaves. Leaves from new tea tree strains HK-2 and HK-3 were treated with white light (CK), red light, yellow light, blue light, and purple light for withering, and UPLC (Ultra Performance Liquid Chromatography) was used to detect the content of simple catechins [epigallocatechin (EGC), epicatechin (EC), catechin (C)] and ester catechins[epigallocatechin gallate (EGCG), epicatechin gallate (ECG), catechin gallate (GCG), catechin gallate (CG)] in samples lit for 0, 2, 4, 6, 8, 12, 24 h. Compared with CK, 4 h blue light withering process could significantly increase the content of non-ester catechin in the fresh leaves of HK-2 by 21.64% and the contents of EGCG, ester catechin and total catechin were significantly increased by 23.31%, 38.56% and 35.78% respectively after 6 h treatments. It was worth noting that the EGCG content of HK-3 was significantly increased by 33.18% after 12 h blue light withering treatment, and the total contents of non-ester catechins, ester catechins and catechins were significantly increased by 75.49%, 35.83% and 38.51% respectively after 6 h treatment. Combined with principal component analysis and cluster analysis, the results showed that different light quality withering could regulate the changes of catechins content in fresh leaves of tea plants during the withering process, and blue light withering for 6 h was the optimum process to increase the catechins content in fresh tea leaves.

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    Analysis of Extraction and Structure of Taraxacum kok-saghyz Rubber
    ZHUO Yangpeng, LIAO Xiaoxue, LIAO Lusheng, ZHANG Xuechao, LIAO Shuangquan, ZHANG Fuquan, ZHANG Chen, ZHAO Yanfang
    2021, 42 (12):  3617-3624.  doi: 10.3969/j.issn.1000-2561.2021.12.031
    Abstract ( 41 )   HTML ( 0 )   PDF (2173KB) ( 40 )  

    Rubber was extracted from Taraxacum kok-saghyz (TKS) by alkali, acid and solvent methods. The composition and structure properties of the extracted TKS rubber were analyzed. The purity of TKS rubber was the highest by the solvent method. According to the analysis of IR and NMR, the structure of TKS rubber was similar to that of Hevea rubber. The cross-linking density of TKS rubber was lower than that of Hevea rubber. The molecular weight,of TKS rubber was smaller than that of Hevea rubber, and the molecular weight distribution was narrower and more uniform. The P0 and Mooney viscosity of TKS rubber was much lower than that of Hevea rubber, so it is difficult to produce and process the TKS rubber.

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    Volatile Components of Latex from Eight Mango Cultivars and Mechanism of Latex
    MU Junxia, GAO Zhaoyin, GONG Deqiang, LI Min, WU Jiali, YU Jing, LI Junguo, HU Meijiao
    2021, 42 (12):  3625-3632.  doi: 10.3969/j.issn.1000-2561.2021.12.032
    Abstract ( 35 )   HTML ( 1 )   PDF (2250KB) ( 31 )  

    In order to provide scientific references for the identification of main volatile components of mango latex, the latex from eight mango cultivars, including ‘Tainoung No.1’, ‘Guifei’, ‘Chun Hwang’, ‘Yuwen’, ‘Red Ivory’, ‘Sijimi mango’, ‘Jinsui’ and ‘Hongshanlin’, were determined by the GC-MS method. The compounds with matching degree more than 90% were reserved according to NIST 11 standard mass spectrometry library and analyzed the differences among latex from different mango cultivars. The changes before and after peel burned were observed under a VHX-5000 Super-high magnification lens zoom 3D microscope, which provided a reference for preliminary exploration of the mechanism of latex. Thirty kinds of compounds with a matching degree greater than 90% were detected from the cultivars. The compounds were composed of terpenes, phenols, aldehydes and alkanes. The main volatile components were terpenes, and there were a small amount of phenols, aldehydes and alkanes. Ten common compounds were detected in the latex from the cultivars, including α-pinene, 3-carene, α-phellandrene, 4-carene, (R)-(+)-limonene, sabinene, (1R)-(+)-α-pinene, terpinolene, L-caryophyllene and 2,4-Di-tert-butylphenol, among which the main volatile components were 3-carene and terpinolene. The latex from different mango cultivars were clustered into different groups according to the PCA score map. Based on the distance among the cultivars, they were classified into five groups. The first group included ‘Guifei’ and ‘Chun Hwang’, the second group included ‘Tainoung No.1’ and ‘Sijimi mango’, the third group included ‘Red Ivory’ and ‘Jinsui’, the fourth group was ‘Yuwen’, and the fifth group was ‘Hongshanlin’. The distance between two mango cultivars in the same group was small, which indicated the great similarity between them. The distance was large in different groups, which indicated that the main volatile components and relative content were quite different. Mango latex caused browning damage in the lenticels of fruit skin. ‘Tainoung No.1’ had slight burn after contacting with the latex for 1 hour, and ‘Guifei’ had obvious burn after contacting with the latex for 10 min. This study would provide a theoretical basis for revealing the mechanism of latex.

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    Effects of Mixed Silage of ‘Reyan No. 4’ with Amomum villosum Stem and Leaf on Its Nutritional Components and Fermentation Quality
    LIN Hongling, ZHOU Hanlin, DONG Rongshu, WU Qun, CHEN Yonghui, Ma Xingbin, HAN Jiancheng
    2021, 42 (12):  3633-3638.  doi: 10.3969/j.issn.1000-2561.2021.12.033
    Abstract ( 36 )   HTML ( 1 )   PDF (1498KB) ( 39 )  

    In order to effectively utilize the agricultural waste in Tropical Zones, the nutritional composition and fermentation quality of ‘Reyan No. 4’ silage was studied by adding different proportions of Amomum villosum stem and leaf. The optimum proportion of mixed silage was selected to improve the nutritional quality of feed. According to the random design experiment, fresh stems and leaves of ‘Reyan 4’ Wangcao and A. villosum were mixed with ratios 100∶0 (CK), 90∶10 (Group A1), 80∶20 (group A2), 70∶30 (Group A 3). Each group was treated with 10 mg/kg EM bacteria, and the samples were collected after 30 days of silage. LA/AA was greater than 2 in all groups, a small amount of propionic acid (PA) and butyric acid (BA) were detected. The sensory quality of A2 and A3 groups was excellent, and the dry matter (DM), crude protein (CP), crude fat (EE) and crude ash (ASH) of each treatment group increased with the proportion of stem and leaf of A. villosum, the pH of silage increased significantly. The contents of ammonium nitrogen/total nitrogen (NH3-N/TN), lactic acid (LA) and acetic acid (AA) decreased gradually. The content of NH3-N/TN in A3 were significantly lower than those in CK and A1 Group (P<0.05), the contents of LA and AA in each treatment group were significantly lower than those in CK (P<0.05). However, the contents of LA and AA were not significantly different among the treatments (P>0.05). The contents of DM, CP, EE and ASH in A3 were significantly higher than those in CK (P<0.05), and the content of WSC was significantly lower than those in CK (P<0.05). There was no significant difference among A1, A2 and A3 (P>0.05). NDF and ADF contents were significantly lower than that of CK (P<0.05). 30∶70 ratio of A. villosum stem and leaf to ‘Reyan No. 4’ Wangcao is recommended for silage.

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    Agricultural Ecology & Environmental Protection
    Structures and Biodiversity of Microbial Communities in Rhizosphere Soil of Red Root Rot Disease and Healthy of Hevea brasiliensis
    TU Min, CAI Haibin, PENG Yanlin, GUAN Xin, FU Xue, ZENG Xia, HU Yanshi
    2021, 42 (12):  3639-3645.  doi: 10.3969/j.issn.1000-2561.2021.12.034
    Abstract ( 42 )   HTML ( 6 )   PDF (1985KB) ( 41 )  

    To explore the effect of red root rot disease on the microbial diversity of rhizosphere soil, the rhizosphere soil of diseased and healthy Hevea brasiliensis were selected as the research objects, and Illumina Miseq high-throughput sequencing was used to analyze the microbial community structure and composition differences. The physiochemical properties of the soil samples were also analyzed. Infestation caused by red root rot decreased the fungi diversity of rhizosphere soil significantly, the number of OTU and Alpha diversity index were both lower than those in the healthy soil. The bacteria diversity in the diseased soil was slightly higher than that in the healthy soil. The community structure of fungi in the diseased soil changed significantly, and the change of bacterial community structure was small. At genus level, there were totally 289 kinds of soil fungi, 525 kinds of bacteria detected, the relative abundance of pathogenic Ganoderma in the diseased soil was as high as 31.32%, which was not detected in the healthy soil. The content of organic matter, available phosphorus, available potassium and pH value of the rhizosphere soil were higher in the healthy soil, and the content of hydrolysable nitrogen was higher in the diseased soil. Correlation analysis showed that the abundance of Ganoderma was negatively correlated with the content of organic matter and pH value. This research revealed the micro-ecological changes of the rhizosphere with the occurrence of red root rot disease and would provide theoretical support for developing a comprehensive control method of red root rot.

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    Effects of Different Land Use Types on Soil Phosphorous Availability and Phosphate-solubilizing Bacterial Community Structure
    WANG Dungang, ZHANG Qiaoyan, CAO Wenchao, ZHOU Guangfan, WANG Jinchuang
    2021, 42 (12):  3646-3654.  doi: 10.3969/j.issn.1000-2561.2021.12.035
    Abstract ( 60 )   HTML ( 0 )   PDF (1859KB) ( 50 )  

    To investigate the effects of different land use types on phosphorous availability and phosphate-solubilizing bacterial community, the soil of conventional inorganic managed Longan orchard (LO), the organic managed tea plantation (OTP) transformed from Longan orchard and the conventional inorganic managed tea plantation (CTP) transformed from Longan orchard were studied in Baisha County, Hainan Island. In the study, the community structure of soil phoD functional microorganisms were determined by Illumina sequencing, and analyzed the correlation between soil AP and phoD functional microorganisms and acid phosphatase.After converting LO into CTP, the contents of TN, TP, AK, SOC and pH were significantly reduced in the 0-10 cm soil layer, and the contents of TN, TP, SOC and pH were significantly reduced in the 10-20 cm soil layer. After LO converting into OTP and CTP, the contents of soil AP decreased by 16% and 71% in the 0-10 cm soil layer, respectively. The content of soil AP was increased by 56% in the OTP and decreased by 65% in the CTP in the 10-20 cm soil layer. Moreover, the phoD functional microbial community structure was mainly affected by land use types, rather than soil depth. The RDA analysis revealed that soil pH, TK, AK and NO3 --N were the main influencing factors driving for phoD functional microbial community structure change. Meanwhile, the content of soil AP was closely related to phoD functional microorganisms and Betaproteobacteria. These results indicated that the transformation of LO into OTP and CTP changed the phoD microbial community structure and reduced the the content of TP in the soil of OTP and AP in the soil of CTP. Meanwhile, OTP could increase soil available phosphorus content compared with CTP.

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    Effects of Continuous Cropping of Passiflora edulis on Soil Bacterial Community Structure
    CAI Guojun, GUO Chunyan, TAN Zhongting, WU Fengchan, LI Anding, ZHANG Limin, PENG Xi
    2021, 42 (12):  3655-3663.  doi: 10.3969/j.issn.1000-2561.2021.12.036
    Abstract ( 45 )   HTML ( 5 )   PDF (2313KB) ( 38 )  

    Soil bacteria play key roles in determining soil health and plant growth. Previous studies showed that continuous cropping of crops altered a significant imbalance of soil bacteria communities. Five soil samples from 0 year to 4 years (TZ, TF, TS, TT, TFo ) of continuous cropping P. edulis were used as the materials, 16S rRNA was analyzed based on the Miseq platform of Illumina Company to study the soil bacterial community structure and diversity in different continuous cropping years of P. edulis. A total of 2418 OTUs for bacterial diversity were generated from the five samples, which were classified in 28 phyla, 70 classes, 170 orders, 269 families, 465 genera and 963 species. Among them, Proteobacteria, Acidobacteria and Actinobacteria were the dominant phylum in the tested samples. The Ace, Chao, Shannon and Coverage index of soil bacteria increased first and then decreased with the increase of continuous cropping years. Continuous cropping of P. edulis had a significant impact on the structure of soil bacterial communities, but the influence rule on the main types species was different from the research results of other crops, with the relative abundance of Chloroflexi, Firmicutes and Bacillus increased with the increase of continuous cropping years. The research results would provide a research foundation and theoretical basis for the mechanism of continuous cropping obstacles of P. edulis in the further studies.

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    Effects of Successive Multi-generation Planting of Rubber Trees on Soil Aggregates and Soil Organic Carbon in Rubber Plantations
    DONG Hao, CHA Zhengzao, ZHANG Xiang, GUO Pengtao, HUANG Yanyan, ZHU Ziyi, WANG Guowei
    2021, 42 (12):  3664-3670.  doi: 10.3969/j.issn.1000-2561.2021.12.037
    Abstract ( 40 )   HTML ( 1 )   PDF (1531KB) ( 45 )  

    Soil aggregates and soil organic carbon (SOC) are important indicators of soil quality. Exploring the effects of successive multi-generation rubber planting on soil aggregates and SOC can provide theoretical support for understanding the evolution law of soil quality in rubber plantations. In this study, the spatial and temporal intergenerational method was used to collect soil samples in layers (0-20 cm, 20-40 cm and 40-60 cm) from rubber plantations of different generations (first generation, second generation and third generation) with the same parent material, soil type and climatic conditions in Danzhou, Hainan. The changes of soil aggregates, bulk density, porosity and organic carbon (SOC) with planting generations and soil depth were studied. Soil bulk density of the third generation was significantly higher than that of the first and second generation rubber plantations (P<0.05), and porosity, MWD and GMD of the first generation were significantly higher than that of the third generation rubber plantations (P<0.05). In different soil depth, porosity decreased significantly with the increase of soil depth (P<0.05). The proportion of large and medium aggregates in the third generation was significantly lower than that in the first generation of rubber plantation (P<0.05), and the proportion of large and medium aggregates in the 0-20 cm soil layer was significantly higher than that in the 40-60 cm soil layer (P<0.05). On the contrary, the proportion of soil microaggregates in the first generation was significantly lower than that in the third generation (P<0.05), and the proportion of microaggregates increased with the soil depth increasing (P<0.05). The soil total organic carbon content of the first generation was significantly higher than that of the third generation (P<0.05), and the soil organic carbon content of the 0-20 cm soil layer was significantly higher than that of the 40-60 cm soil layer (P<0.05). The content of organic carbon in soil aggregates decreased significantly with the increase of planting generation and soil depth (P<0.05). The organic carbon content of both medium and micro aggregates in 0-20 cm soil layer was significantly higher than that in 40-60 cm soil layer (P<0.05). The above results indicated that the soil degraded in some degree after multiple successive generations of rubber tree plantation.

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    Diversity of Fungi Communities in Rhizosphere Soil of Resistant and Susceptible Mulberry Against Bacterial Wilt in Hainan
    TU Nana, WU Huazhou, LOU Dezhao, LU Fuping, GENG Tao, WANG Shuchang
    2021, 42 (12):  3671-3677.  doi: 10.3969/j.issn.1000-2561.2021.12.038
    Abstract ( 43 )   HTML ( 1 )   PDF (2514KB) ( 39 )  

    The structure and diversity of fungi communities in mulberry rhizosphere soil were analyzed to indicate the correlation with resistance and susceptibility to bacterial wilt. The ITS1-ITS2 region of fungi were amplified and sequenced to analyze the structure and diversity of fungi communities in resistant mulberry variety ‘Kangqing 283’ × ‘Kangqing 10’ and susceptible mulberry variety Qiangsang 1 by Illumina miseq high-throughput sequencing technology. The dominant phylum of ‘Kangqing 283’ × ‘Kangqing 10’ were Cystophyta (54.86%), Basidiomycota (24.67%) and Zygomycota (3.17%), while the dominant genus Paecilomyces (5.71%), Fusarium (5.43%) and Cochilobolus (1.29%). The dominant phylum in ‘Qiangsang 1’ were Cystophyta (68.04%), Basidiomycota (15.12%) and Zygomycota (1.90%), while the dominant genus Pythium (8.46%), Fusarium (5.44%) and Cochilobolus (2.22%). The most important fungi communities in the rhizosphere soil of resistant varieties were Conchochaetales, Crustaceaceae and uncultured families of Angiosporaceae, while Coniochaetales, Crustaceaceae, Serpulaceae and Cantharellales-fam-incertae-sedis in the sensitive varieties. Paecilomyces and arbuscular mycorrhizal fungi Coccidiales are widely used as the biocontrol fungi, which were found as the dominant fungi in the rhizosphere soil of resistant varieties and might be directly related to the resistance. Although there were no significant differences in the fungi communities abundance of the two mulberry varieties, the dominant fungi such as Penicillium and arbuscular mycorrhizal Angiocystidea detected in the resistant varieties were closely related with its resistance. The results yield insights to screen antagonistic fungi and effective control methods against mulberry bacterial wilt in Hainan province.

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    Fine Regionalization of Hainan Island Mango Climate Suitability Based on GIS
    ZHANG Mingjie, ZHANG Yajie, ZHANG Jinghong, YANG Jing, LIN Shaowu
    2021, 42 (12):  3678-3684.  doi: 10.3969/j.issn.1000-2561.2021.12.039
    Abstract ( 43 )   HTML ( 3 )   PDF (6946KB) ( 39 )  

    Based on the observation data of 18 national meteorological stations in Hainan from 1966 to 2019, the correlation between meteorological yield of mango per unit area and temperature, precipitation, sunshine and relative humidity of mango in each growth period in 18 cities and counties of Hainan Island was analyzed,and the average temperature at flowering stage, average temperature at fruit development stage and annual accumulated temperature≥10 ℃ were selected as regionalization indexes when the influence of slope factor was considered. Based on GIS, the refined climate regionalization of mango planting in Hainan was carried out by using the method of set optimization. The climate suitable areas for mango planting in Hainan are mainly distributed in the coastal towns of Changjiang, Dongfang, Ledong, Sanya, Lingshui, Wanning, Qionghai, etc. The unsuitable areas are mainly distributed in most of Wuzhishan, south of Baisha, south of Changjiang, northeast of Ledong, north of Sanya and north of Lingshui. And the other areas are sub-suitable areas. The results could provide scientific basis for the planning of mango planting layout and industrial structure adjustment in Hainan Island.

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    Effect of Canopy Gaps on Soil Respiration in Tropical Montane Rainforest in Jianfengling, Hainan
    LI Jialing, XU Quan, YANG Qiu, SU Tianyan, FU Qunyou, YANG Huai, LIU Wenjie
    2021, 42 (12):  3685-3691.  doi: 10.3969/j.issn.1000-2561.2021.12.040
    Abstract ( 90 )   HTML ( 1 )   PDF (1650KB) ( 54 )  

    The effect of canopy gaps on soil respiration could provide scientific basis and theoretical reference for accurate estimating soil carbon emissions and effective management of soil organic carbon (SOC) accumulation in the tropical montane forest ecosystem. In this study, 60 hm2 dynamic observation plots and the natural canopy gaps in the tropical montane rainforest observation sites of the Jianfengling National Natural Reserve in Hainan Island,were selected as the research objects. Meteorological factors, soil environmental parameters, soil respiration and other indicators were observed and investigated regularly. Based on the observation data, daily and seasonal patterns and differences of soil respiration between the inside and outside of canopy gaps (which was formatted by typhoon interference) were analyzed. Then, the effect of canopy gaps on soil respiration was illustrated. In addition, the effects of litter on soil respiration were analyzed through removing/keeping the litter, and the characters of soil respiration at both inside. The relationship between soil respiration and environmental factors was determined using the best available structural model method, and the characteristics affecting the factors and differences of soil respiration were analyzed inside and outside the canopy gaps. In the result, there was a significant difference between relative air humidity, soil temperature and soil water content (P<0.01). There was no significant difference between the air temperature of inside and outside the canopy gaps (P>0.05). The average soil respiration rate was (3.29±0.54) μmol/(m2·s) at the inside canopy gaps, and the average soil respiration rate at the outside canopy gaps was (2.38±0.51) μmol/(m2·s). At the monthly scales, the discharge rate of soil respiration showed a multi-peak curve at the both inside and outside forest gaps and the variation trend was almost the same. The overall of soil respiration at rain season was greater than that at the dry season. There was a significant difference between relative soil respiration rate of inside and outside the canopy gaps (P<0.05). Soil respiration was quite different both inside and outside forest gaps. Soil temperature (5 cm) was the most important environmental factors affecting soil respiration inside the forest gap.

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    Microbial Colonization and Communities on Microplastics in Urban Mangrove System
    FU Qianqian, LI Dazhen, ZHANG Yuqing, DENG Hui, FENG Dan, ZHAO Yuanyuan, YU Huamei, WU Xiaochen, GE Chengjun
    2021, 42 (12):  3692-3698.  doi: 10.3969/j.issn.1000-2561.2021.12.041
    Abstract ( 41 )   HTML ( 1 )   PDF (4688KB) ( 61 )  

    Recently, microplastic pollution has become a new global environmental problem. Due to the strong hydrophobicity and large specific surface area, microplastics exposed to the environment can provide a new ecological site for microorganisms. Mangrove system is the “source” and “sink” of pollutants. Urban mangrove system was selected to study the diversity and composition characteristics of the bacterial community structure of the microplastics surface in the system. The method of in-situ exposure experiment, scanning electron microscope and 16S rDNA high-throughput sequencing technology were used to investigate the surface morphology characteristics and bacterial community structure of four types of microplastics (PE, PS, PVC, PLA). The results showed that obvious microbial aggregates were observed on the surfaces of the four microplastics after exposure (labeled as LPE, LPS, LPVC, LPLA), mainly bacilli and cocci (shape). There were significant differences in the total amount of biofilm on the surfaces of the four microplastics, which was represented by LPE>LPLA>LPS>LPVC. The results of high-throughput sequencing presented that the bacterial communities on the surfaces of the four microplastics mainly included Proteobacteria and Bacteroidetes. However, in the water environment, Cyanobacteria_Chloroplast, Proteobacteria, Actinobacteria and Bacteroidetes were the dominant flora. Based on the analysis of the diversity of the bacterial community, it was found that there were significant differences between the bacterial community structure in the microplastic surface biofilm and the surrounding water body, and the bacterial community structure composition on the surfaces of the four microplastics were similar. Since microplastics were accumulated in the mangrove area, it is necessary to study the microbial community characteristics of microplastic surface biofilm in order to provide an important reference for in-depth understanding the environmental behavior and ecological risk assessment of microplastics in urban mangrove systems.

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