Welcome to Chinese Journal of Tropical Crops,

#### Table of Content

25 November 2020, Volume 41 Issue 11
Omics & Biotechnology
 Cloning and Expression Analysis of a SWEET Family Gene from Annona squamosa L. AN Zhenyu,FANG Ren,HUANG Weixiong,YAO Jinyan,WEI Shuotong 2020, 41 (11):  2143-2148.  doi: 10.3969/j.issn.1000-2561.2020.11.001 Abstract ( 343 )   HTML ( 41 )   PDF (3404KB) ( 248 )   The fruit at different stages of Annona squamosa L. was used as the experimental material. A gene named AT-SWEET16-1 with 1227 bp was cloned by RT-PCR, which encoding 408 amino acids. The amino acid sequence had a α-helix THB domain at the N-terminal. Bioinformatics analysis showed that the molecular weight of the protein was 44.8 kDa, and the isoelectric point was 8.87. Evolutionary analysis showed that it was associated with Phoenix dactylifera). qRT-PCR analysis showed that the gene was expressed in roots, stems, tender leaves, old leaves, flower buds, buds, young fruit and mature fruit. The expression of AT-SWEET16-1 gene in tissue was as follows: mature fruit>stem>root>flower bud>young fruit>old leaf>tender leaf. The expression of the gene in different fruit development stages was the highest in fruit stalk, relatively low in pulp and pericarp, and the lowest in seed, and the highest expression in fruit stalk and pulp was at fruit maturity stage. It was found that the gene was expressed in the phloem of the fruit stalk and between the cell membrane of the pulp cell wall, indicating that the gene played a role in the progress of the fruit development and the transport of plant nutrients.
 Association Studies of Plant Architecture Traits and SSR Markers in Nelumbo Adans. YANG Dan,DU Fengfeng,CHANG Yajun,CUI Jian,SUN Linhe,LIU Xiaojing,YAO Dongrui 2020, 41 (11):  2149-2155.  doi: 10.3969/j.issn.1000-2561.2020.11.002 Abstract ( 318 )   HTML ( 24 )   PDF (2066KB) ( 360 )   Totally 129 lotus accessions with different architecture were used as the experimental material. The leaf height, flower height and leaf diameter were determined. The accessed lotus population had diverse plant architecture traits. Variation coefficient for leaf height and flower height was 39.68% and 41.69% respectively, and variation coefficient for leaf length and width was 29.70% and 31.41% respectively. 129 lotus accessions were genotyped with 98 pair polymorphic SSR primers. Population structure of lotus accessions was analyzed using the STRUCTURE V2.2 software. Association analysis of lotus architecture traits was performed with the GLM model. The results indicated that lotus accessions were divided into four subgroups. The results distinctly grouped lotus accessions from Chinese lotus and Sino-American hybrids into different clusters. However, the hybrids dispersed among clusters. The results showed that 11 SSR markers were associated with leaf height, flower height, leaf length and width; three markers were associated with all the plant architecture traits, and that might be caused by multiple effects of one gene or genetic linkage. In two years of repeated tests, two markers (SSR132 and SSR458) can be associated with leaf length and width, indicating that these two markers may be less affected by environment.
 Genetic Diversity Analysis of the Potted Chrysanthemum Based on Phenotype and SRAP Marker SHEN Yao,WANG Hanxuan,HOU Haixian,WU Zhiming,ZHOU Hougao 2020, 41 (11):  2156-2164.  doi: 10.3969/j.issn.1000-2561.2020.11.003 Abstract ( 268 )   HTML ( 14 )   PDF (2069KB) ( 231 )   In order to better protect chrysanthemum germplasm resources and lay a foundation for hybrid breeding, the genetic diversity of 30 potted chrysanthemum varieties were studied based on 20 morphological and SRAP markers. The results showed that the phenotypic variation of potted chrysanthemum varieties was abundant. The coefficient of variation of characters was ranged from 14.67% to 78.25%, which were crown width and tongue floret number. The results of principal component analysis showed that the contribution rate of the first five principal components was 76.68%, which comprehensively reflected the importance of flower size, leaf shape and flower color. Based on the cluster analysis of phenotypic traits, 30 potted chrysanthemum cultivars could be divided into three groups. GroupⅠ, GroupⅡ and Group Ⅲ consisted of 14, 2 and 14 varieties correspondingly. The clustering results based on phenotypic traits were related to flower diameter and natural florescence period. Based on SRAP marker technology, 11 pairs of polymorphic primers were screened out and a total of 1866 polymorphic loci were obtained, with the polymorphic proportion as high as 92.61%. The genetic similarity coefficient between cultivars was ranged from 0.67 to 0.85, indicating that there were some genetic variations in the 30 cultivars. The samples could be divided into three groups based on the NJ tree. GroupⅠ, Group Ⅱ and Group Ⅲ consisted 17, 10 and 3 varieties correspondingly. However, the clustering results of the two grouping techniques showed that there was no good correlation between the two markers, which might be related to the complex genetic background of chrysanthemum materials and the limitations of experimental selection.
 Transcriptome Analysis of Carotenoid Metabolism Differential Genes in Pomelo Bud Strain PAN Heli,PAN Tengfei,SHE Wenqin,XU Shirong,LI Xiaoting,HUANG Hantang,CHEN Yuan,WU Shaohua,PAN Dongming 2020, 41 (11):  2165-2175.  doi: 10.3969/j.issn.1000-2561.2020.11.004 Abstract ( 364 )   HTML ( 20 )   PDF (6583KB) ( 264 )   In order to study the molecular mechanism of carotenoid metabolism of ‘Guanximiyou’ pomelo red mutant line, ‘Guanximiyou’ pomelo (GX), its budding first generation ‘Hongroumiyou’ (HR) and budding second generation ‘Sanhongmiyou’ (SH) were used to study the carotenoid metabolism in the pulp of the three varieties at three development stages by the RNA SEQ technology. By bioinformatics analysis, 10 differentially expressed genes were isolated to participate in the biosynthesis of carotenoids, namely, PSY, ZDS, CRTISO1/2, NPQ1, and 9-cis-epoxy carotenoids, the genes of oxygenase (NCED3/5), abscisic aldehyde oxidase (AAO3), ABA 8’-hydroxylase (CYP707A1), carotenoid cleavage dioxygenases gene (CCD4). Co expression analysis revealed that the expression patterns of seven family transcription factors were highly correlated with carotenoid synthesis genes, which were MADS, bZIP, bHLH, MYB, AP2/ERF, NAC and WRKY. The expression patterns of some genes were verified by real-time quantitative PCR (qRT-PCR), and the results were highly consistent with those of RNA-seq. In addition, DEGs enrichment analysis of primary and secondary metabolic pathways in ‘red flesh honey pomelo’ showed that during the accumulation of carotenoids, genes of cell wall, lipid and flavonoid metabolism were abundant. The results showed that the red flesh mutation of GX was caused by the differential expression of carotenoid metabolism related enzyme genes and the regulation of transcription factors; at the same time, the red bud mutation in flesh was accompanied by the mutation related to juice granulation. This may provide a valuable reference for further study on the formation and accumulation of carotenoids and juice granulation, and also provide a way to analyze the mechanism of different color mutation and juice granulation in pomelo fruit.
Germplasm Resources, Genetics & Breeding
 Identification and Domestication Cultivation of a Wild-type Ganoderma lingzhi Strain from Lincang, Yunnan ZHANG Yanzhen,ZHOU Huiming,BAI Yuying,CHAI Hongmei,GU Guanghong,ZHAO Yatong,TIAN Libo,MAO Mingjuan 2020, 41 (11):  2176-2182.  doi: 10.3969/j.issn.1000-2561.2020.11.005 Abstract ( 304 )   HTML ( 11 )   PDF (1773KB) ( 224 )   An optimal medium was screened for the cultivation of a wild-type Ganoderma lingzhi, which are the basis of its mass production. In this paper, a strain of YAASM4672 was isolated from a wild mushroom fruiting body of Ganoderma lingzhi, from Lincang, Yunnan. Taxonomic status was identified based on its morphology and ITS sequence analysis, and nine media of culture spawn were designed for the determination of its cultivation characteristics. The result showed that the wild strain of YAASM4672 was G. lingzhi, and the morphological characteristics were consistent with its molecular identification. Formula 2 of culture spawn were the best for the mycelial growth and agronomic characters of fruiting body (soil mulched group was better than the open field group) of strain YAASM4672. Its mycelia colour was white and dense, the time of sackful was 38 d, and the growth rate of mycelia was (5.89±1.01) mm/d. The pileus was yellow, diameter was 66.00 mm, and average growth rate was (4.14±1.07) mm/d, which were significantly (P<0.05) or extremely significantly (P<0.01) different compared with other formula. Stipe was brownish yellow, its length and diameter was 84.00 mm and 18.00 mm respectively. In short, the optimal medium for artificial cultivation of strain YAASM4672 was 78% corn cob, 18% rice bran, 2% sorghum flour, 1% gypsum powder, and 1% white granulated sugar. Soil mulched can promote the growth and development of its fruiting body.
 Effects of Different Hormone Types and Concentrations on Softwood Cutting Propagation of Calophyllum inophyllum ZHANG Yangfeng,REN Zheng,LIN Mingping,CAI Weijing,SHI Guozheng,YU Bin 2020, 41 (11):  2183-2189.  doi: 10.3969/j.issn.1000-2561.2020.11.006 Abstract ( 229 )   HTML ( 17 )   PDF (1233KB) ( 193 )   The effects of different hormone types and concentrations, 1-naphthylacetic acid (NAA), 3-indolebutyric acid (IBA) and ABT-1 rooting powder (ABT) on the leaf-growing and rooting characteristics were studied on the softwood cuttings of Calophyllum inophyllum. A comprehensive evaluation was given based on membership function. The results showed compared with the control, different hormone types and concentrations significantly affected leaf sprout rate, new leaf number, new leaf area, rooting rate, partial root rate, adventitious root number, adventitious root number, lateral root number and lateral root length, but had no significant effects on the leaf retention rate. Under different hormone treatment, the leaf sprout rate and rooting rate of cuttings was 21.7% to 66.7% and 43.3% to 98.3%, respectively, while the leaf sprout rate and rooting rate of control treatment were 0. Based on the comprehensive analysis of membership function method, the promoting effect of hormones on cutting was NAA>ABT>IBA. The average leaf sprout rate and rooting rate of the cuttings treated with NAA were 62.1% and 95.4%, respectively increased by 47.5% and 30.2% compared with the treatments of ABT, and increased by 62.0% and 57.9% compared with the treatments of IBA. 1000 mg/L of NAA was the best combination for the softwood cuttings of C. inophyllum, while the leaf sprout rate was 61.7% and the rooting rate was 95.0%.
 Ploidy Induction Effect of Dinitroaniline Herbicides on the Single-headed Cutting Chrysanthemum ‘Iwa-no-hakusen’ YANG Huiting,CHEN Guixin,HU Jihong,JI Yuting,KANG Jianban,PAN Tengfei,SHE Wenqin 2020, 41 (11):  2190-2196.  doi: 10.3969/j.issn.1000-2561.2020.11.007 Abstract ( 282 )   HTML ( 12 )   PDF (3177KB) ( 216 )   In this study, the stalk bud stems of Japanese single-headed cutting Chrysanthemum ‘Iwa-no-hakusen’ sterile seedlings were used as the materials, and two dinitroaniline herbicides (pendimethalin and trifluralin) were used at different concentrations and soaking time. Induction treatment was carried out and inoculated into rooting medium to induce whole plants. The ploidy inducing effect of herbicide on the sterile stem segment of cutting Chrysanthemum ‘Iwa-no-hakusen’ was summarized by statistical analysis and comparison of early mutant morphology, chromosome count of root tip cells, leaf stomatal characteristics, agronomic traits and flowering morphology. The results showed that the induction effect was the best when induced by 200 μmol/L pendimethalin and 200 μmol/L trifluralin for 36 h and 24 h, the induction rate was 25.00% and 40.00%. The number of chromosomes in the plants increased, and the agronomic traits changed significantly. The leaf guard cells and stomata of the mutant plants increased, the stomatal density decreased, the plant height and the internode length were significantly shortened, the stem diameter, leaf length and leaf width increased significantly, and the shape of the tongue petals showed various changes and the number increased.
 Genetic Diversity Analysis on the Major Agronomic Traits of 90 Oil Palm Germplasms ZHOU Lixia,ZHAO Zhihao,CAO Hongxing 2020, 41 (11):  2197-2204.  doi: 10.3969/j.issn.1000-2561.2020.11.008 Abstract ( 246 )   HTML ( 14 )   PDF (1703KB) ( 231 )   In order to make deep and efficient use of oil palm germplasm resources, the genetic diversity and relationship of 90 oil palm germplasm resources introduced in recent years were analyzed based on 20 agronomic traits. The results showed that the genetic diversity index of ear weight was the highest (3.26), and the smallest was fruit shape (0.865). The variation coefficient of different characters was different, the biggest was ear weight (43.99), and the smallest was stem height (10.41). Five main factors were extracted by principal component analysis which were plant height factor, ear weight, fruit weight, flesh oil content and kernel oil content, and the cumulative contribution rate was 70.272%. Through cluster analysis, the tested materials were divided into four groups, among which 36 oil palm materials of group I showed dwarf plant, dwarf stem, high oil yield and good quality of palm oil, which were ideal materials for breeding high oil content and high quality palm oil.
 Screening of Sugarcane with High Nitrogen Efficiency at Seedling Stage YANG Liu,LIAO Fen,Muhammad ANAS,LI Qiang,PENG Lishun,HUANG Dongliang,LI Yangrui 2020, 41 (11):  2205-2218.  doi: 10.3969/j.issn.1000-2561.2020.11.009 Abstract ( 231 )   HTML ( 14 )   PDF (3121KB) ( 225 )   The purpose of the experiment is to screen high nitrogen use efficiency (NUE) genotypes under a low nitrogen pressure selection system. Furthermore, the important indexes which affecting the NUE of sugarcane were analyzed. The results could provided a theoretical basis for the high NUE breeding and cultivation of sugarcane. In the study, seedlings of 58 sugarcane genotypes were evaluated in a hydroponic experiment with low-N (0.2 mmol/L N) and normal-N (2 mmol/L N) treatment. The growth, dry biomass and N cumulative and distribution characteristic in various organs were evaluated according to descriptive statistic, principal component analysis and cluster analysis. The results indicated that morphology, biomass, nitrogen efficiency traits showed high genotypic variation for N treatments. Under low-N treatment, the dry biomass of 58 genotypes varied from 0.64 to 14.75 g/plant, nitrogen accumulation was from 5.53 to 63.00 mg/plant and NUE was from 115.40 to 279.30 g/g. Four factors were extracted with variance contribution approximated to 92.35%, according to 25 parameters such as dry biomass and N uptake with N deficiency. And another five factors were extracted with variance contribution approximated to 82.21%, according to 19 parameters under both normal and low N treatment such as nitrogen transfer coefficient, genetic potential. The data revealed that dry biomass (whole plant, leaf, root), N uptake (whole plant, leaf, shoot), NUE (whole plant, leaf), leaf relative NUE, shoot relative dry weight, shoot relative N uptake, shoot genetic potential were the key factors that involved in sugarcane high NUE. 58 sugarcane genotypes were clustered into four group: high NUE group, slightly higher NUE group, slightly lower NUE group and low group.
Plant Cultivation, Physiology & Biochemistry
 Intercropping with Pandanus amaryllifolius Roxb. Improved Root Growth of Areca catechu L. and Soil Enzyme Activities YU Huan,TANG Jinxuan,LI Qiansong,QIN Xiaowei,ZONG Ying,HAO Chaoyun,BAI Tingyu 2020, 41 (11):  2219-2225.  doi: 10.3969/j.issn.1000-2561.2020.11.010 Abstract ( 304 )   HTML ( 13 )   PDF (1813KB) ( 250 )   The root growth of Areca catechu L. (arecanut) and Pandanus amaryllifolius Roxb. (pandan) with the soil enzyme activities was studied in the monoculture and intercropping systems with pot experiments. The results showed that the accumulation of arecanut dry matter was promoted in the intercropping system, the dry matter distributed to the root increased, and the dry matter in underground significantly increased over the arecanut monoculture. The dry matter accumulation of pandan was no significantly different between intercropping and pandan monoculture. SPAD reading of arecanut leaves significantly increased after intercropping, however, there was no significant difference for pandan. The total root length, total root surface area and root number of arecanut significantly increased in the intercropping system, which increased by 78.64%, 50.96% and 81.22%, respectively, compared with the arecanut monoculture. The effect of intercropping on the arecanut root growth was greater than that of pandan. The activity of acid phosphatase, catalase and peroxidase in the intercropping soil was significantly higher than that in the arecanut monoculture. The activity of urease was not significantly different between intercropping and arecanut monoculture, however, that in the intercropping system was significantly lower than that in pandan monoculture. The activity of soil peroxidase was positively correlated with root number and root volume. There is less competition between the roots of arecanut and the pandan. Compared with arecanut monoculture, the arecanut and pandan intercropping system can promote arecanut root growth, increase soil enzyme activity.
 Selection and Optimization of Matrix for Seedlings of Dendrobium sinense in vitro YAO Xiaojian,SONG Xiqiang,YANG Fusun 2020, 41 (11):  2226-2231.  doi: 10.3969/j.issn.1000-2561.2020.11.011 Abstract ( 237 )   HTML ( 18 )   PDF (1315KB) ( 252 )   Substrate plays an important role in the artificial domestication and cultivation of Dendrobium sinense seedlings by affecting the water and fertilizer absorption and root aeration, and then affecting the growth of D. sinense seedlings. In this experiment, the tissue culture plantlet of D. sinense was used as the research object, and four media were used to test the plantlet. By measuring the survival rate, morphological index, strong seedling index and photosynthetic index of the tissue culture plantlet, the suitable media was selected. The results showed that the porosity and air-water ratio of 16.3 g water moss packed in 5 cm transparent plastic cup were higher, which was 42.1% and 2.51; the water conservation and aeration were good, which were beneficial to the rooting and sprouting of the tissue cultured seedlings of D. sinense. The survival rate of the tissue cultured seedlings was higher, which was 56.3%, and the strong seedling index was 0.016; the relative chlorophyll content and net photosynthetic rate were the highest; the porosity and air-water ratio of 6.0 g water moss per hole in the 105 hole disc were relatively low, and the survival rate of plantlets was low because of less matrix. Therefore, 16.3 g water moss in a 5 cm transparent plastic cup can be used as a better substrate for the cultivation of D. sinense.
 Effects of pH on Laccase Activity of Lentinula edodes, Pholiota nameko, and Flammulina velutipes Grown in Different State Media ZHANG Weirui,LIU Shengrong,ZHOU Xiuzhao,RUAN Junfeng,CHEN Weiwei,CUI Xiaowei 2020, 41 (11):  2232-2236.  doi: 10.3969/j.issn.1000-2561.2020.11.012 Abstract ( 215 )   HTML ( 10 )   PDF (1184KB) ( 223 )   Laccase is a key enzyme involved in the degradation and utilization of lignin and has a relationship with mushroom cultivation cycle and product quality. In this work, NaOH was used as the alkalization agent for both solidified media and liquid media, and shell ash was used for solid media, the effect of pH on the activity of laccase of Lentinula edodes, Pholiota nameko, and Flammulina velutipes grown in different state media was investigated for providing a basis for their cultivation. Results showed that the micro-alkalization of all tested culture media could improve the activity of laccase of the species, and its effect was related to media type. The optimal pH values of solidified, liquid, and solid media for L. edodes laccase activity was 6.5, 6.5 and 6.0, respectively, with a 5.3%-14.0% increase of laccase activity in relative to their controls, and for that for F. velutipes was 7.0, 6.0, and 6.5, and the increase in the activity under optimal pH values was 35.9%-343.0% compared with their controls. As to P. nameko, pH 6.0 was optimal for all three media for maximizing laccase activity, 3.1%-94.9% higher than those of their controls.
 Drought Adaptability of Hylocereus undatus WANG Li,ZHANG Xue,ZHAO Xiaozhen,XIAO Tujian,MA Yuhua 2020, 41 (11):  2237-2244.  doi: 10.3969/j.issn.1000-2561.2020.11.013 Abstract ( 259 )   HTML ( 34 )   PDF (1912KB) ( 568 )   Drought stress is an important factor affecting plant growth and development. When plants are in drought stress, they also make some changes to adapt to the environment. This study used ‘Zihonglong’ as the experimental material, a variety of pitaya widely planted in guizhou. In order to lay a theoretical foundation for the physiological research of pitaya, the adaptability of pitaya to drought was evaluated by studying its stem and root growth, stem water content, stomatal movement, leaf temperature change and chlorophyll synthesis. The relative water content in the stem of pitaya was slightly decreased (80%) in drought treatment lasted 16 weeks in soil moisture content 15%. The drought treatment significantly promoted the growth and elongation of new roots, but limited stem elongation and crosswise. Under drought treatment, the stomatal open frequency, stomatal apertura, stomatal size, and stomatal density were lower than those in the control. New stems of pitaya were more sensitive to temperature increase or decrease than mature stems, and the stem surface temperature of drought treatment was higher than that of the control. With the degree of drought, the photosynthetic pigments decreased significantly, and the chlorophyll fluorescence parameters changed. The pitaya stem had strong water retention capacity and was highly resistant to drought. Under drought, the water of pitaya fruit was preferred to providing to the root system to promoting root growth, maintaining stem elongation and growth, while crosswise was inhibited. Under mild and moderate water stress, the photosynthetic capacity of the stem of pitaya did not decrease significantly, while under severe water stress, the photosynthetic efficiency was significantly affected.
 Photosynthetic Characteristics of Phyllostachys edulis under Different Water and Fertilizer Coupling Treatment QIAO Yina,LIU Kai,DENG Zhiwen,XU Linzheng,SU Jianlin,RONG Jundong,CHEN Liguang 2020, 41 (11):  2253-2258.  doi: 10.3969/j.issn.1000-2561.2020.11.015 Abstract ( 261 )   HTML ( 11 )   PDF (1217KB) ( 223 )   Bamboo of different ages was used in a split zone test design with three water replenishment gradients (85%±5%, 65%±5%, 50%±5% of field water holding capacity) and three fertilization gradients (12.50, 6.25, 3.13 kg/m2). The changes in chlorophyll and photosynthetic in different growth month under different treatment was determined and analyzed. Principal component analysis was used to comprehensively judge the optimal water-fertilizer coupling mode under different water and fertilizer coupling treatment, and to explore the water and fertilizer supply mechanism of bamboo under different irrigation conditions to achieve water and fertilizer efficient bamboo forest. The results showed that the chlorophyll content was highest under T4 treatment (field water holding capacity 65% ± 5% fertilizer application 100%). The chlorophyll content of the treated bamboo leaves was the highest in August. The net photosynthetic rate, stomata conductance, intercellular carbon dioxide concentration, and transpiration rate of Moso bamboo leaves in each month of T4 treatment were the highest, indicating that high-fertility water-irrigation could achieve the optimal effect of bamboo growth. During the whole growth stage, the maximum difference of chlorophyll content, net photosynthetic rate, intercellular carbon dioxide concentration and transpiration rate between different water and fertilizer coupling treatment occurred in August, meaning that August was the most critical period for bamboo to apply water and fertilizer.
Plant Protection & Bio-safety
 Effects of Inhibition Citrus Huanglongbing on Catharanthus roseus with Different Arbuscular Mycorrhizal Fungi Species QUAN Dawan,LI Dong,ZHANG Jinlian,SONG Juan,HU Liu,CHENG Tong,HUANG Jinghua,CHEN Tingsu 2020, 41 (11):  2259-2266.  doi: 10.3969/j.issn.1000-2561.2020.11.016 Abstract ( 206 )   HTML ( 9 )   PDF (1843KB) ( 236 )   To provide fundamental references and better ways of preventing and controlling citrus Huanglongbing (HLB), a research was conducted to obtain arbuscular mycorrhizal (AM) fungi that possess plant growth-promoting and disease resistance abilities. The experiment utilized the pot culture method, where 17 strains of AM fungi were inoculated into the roots of Catharanthus roseus that were in the seedling stage. The colonization of different AM fungi strains were analyzed to understand how AM fungi simulating the growth and ameliorate citrus HLB infection in C. roseus under greenhouse conditions. During this process, various measurements were taken, and the agronomic characters, rate of colonization, infection intensity, arbuscular abundance, and HLB infection were analyzed. After C. roseus plants were inoculated with AM strains, strains GZ10, GZ5, and JX70 significantly enhanced the growth of C. roseus. Plants inoculated with GZ10 exhibited 23.1% and 12.1% increase in stem height and diameter, while GZ5 increased leaf number by 12.9%, both in respect to CK. Three strains (GZ1, BNMJ, and PWJ) improved disease resistance to citrus HLB, with a relative prevention rate of 78.39% for GZ1, 66.87% for BNMJ, and 69.75% for PWJ. The result proved that AM inoculation could significantly improve the growth of C. roseus and to some extent increase its disease resistance to citrus HLB.
 Spatial Distribution Pattern and Sampling Technique of Spodoptera litura Larvae in Banana Parks DU Hao,ZHI Jiazeng,LI Zongkai,ZHOU Jinsong,YANG Shaoqiong,CHEN Weiqiang 2020, 41 (11):  2267-2272.  doi: 10.3969/j.issn.1000-2561.2020.11.017 Abstract ( 185 )   HTML ( 6 )   PDF (1326KB) ( 203 )   The Iwao linear regression equation and Taylor’s power law, three kinds of aggregation indexes were used to analyze the spatial distribution of Spodoptera litura larvae in banana parks in three stages: low age (1-2), middle age (3-4) and old age (5-6). The spatial distribution pattern of S. litura larvae was correlated with the larval age, and the aggregation intensity decreased with the increase of larval age. The spatial distribution pattern of 1-4 instar larvae was aggregation distribution, and the aggregation intensity increased with the increase of density. The spatial distribution pattern of 5-6 instar larvae gradually tended to uniform distribution from aggregation distribution, and there was mutual exclusion between individuals. The optimum theoretical sampling formula of S. litura larvae in banana parks was established n=(t2/D2)(1.978/m+3.5119) and the best sequential sampling formula $T(n) = n{m_0} \pm 1.96\sqrt {n(1.978{m_0} + 3.5119m_0^2}$.
 Effects of Different Cassava Cultivars on Antioxidant Enzyme Activities of Paracoccus marginatus CHEN Qian,LIANG Xiao,WU Chunling,CHEN Qing,LIU Ying,ZHANG Zhe 2020, 41 (11):  2273-2279.  doi: 10.3969/j.issn.1000-2561.2020.11.018 Abstract ( 232 )   HTML ( 7 )   PDF (1138KB) ( 249 )   To study the selective mechanism of Paracoccus marginatus to different cassava cultivars, the activity change of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and polyphenol oxidase (PPO) in P. marginatus after feeding on different cassava cultivars for 1, 2 and 4 days were determined by spectrophotometry. The results showed that the activity of antioxidant enzyme showed significant difference while P. marginatus feeding on different cassava cultivars. The activity of SOD in P. marginatus was the lowest after feeding on ‘C1115’, the activity of CAT was the lowest after feeding on ‘SC8002’, and the activity of POD and PPO was the lowest after feeding on ‘SC8’. Furthermore, the activity of SOD, CAT, POD and PPO decreased significantly compared to those of the control after feeding on the ‘J1301’ ‘SC11’ ‘SC8002’ ‘Dongguan Hongwei’ ‘SC8’ ‘Myanmar’ and ‘C1115’ at any analysis time. The above cassava cultivars could inhibit the activity of antioxidant enzymes of P. marginatus, which could interfere their normal reactive oxygen species metabolism and probably possessed the resistance potential to P. marginatus .
 Distribution and Identification of Viruses from Cucumber in Hainan Island CHE Haiyan,CAO Xueren,HE Yanheng,LUO Daquan 2020, 41 (11):  2280-2284.  doi: 10.3969/j.issn.1000-2561.2020.11.019 Abstract ( 324 )   HTML ( 8 )   PDF (1853KB) ( 224 )   From November 2018 to March 2019, a total of 302 suspected virus-infected cucumber leaf samples were collected from 8 regions (Sanya, Ledong, Dongfang, Danzhou, Chengmai, Haikou, Wanning and Wuzhishan) in Hainan Island. Five viruses were detected including Cucumber mosaic virus (CMV), Melon yellow spot virus (MYSV), Cucumber green mottle mosaic virus (CGMMV), Tobacco mosaic virus (TMV) , and Cucurbit chlorotic yellows virus (CCYV) by small RNA deep sequencing and RT-PCR. The detection rate was 32.79%, 31.46%, 23.18%, 9.61% and 2.65%, respectively. Detection rate of co-infection was 11.28%. There were 8 kinds of co-infection types, and the co-infection of two viruses occurred most often. The distribution and species of viruses from cucumber in Hainan were clarified.
 Development of a Homemade Sticky-capture Device for Rubber Bark Beetles and Screening of Field Trapping Parameters GAN Wei,ZHOU Xiang,GUO Jixing,ZHANG Mingxia,LI Zhidong,BAI Chunxiu 2020, 41 (11):  2285-2291.  doi: 10.3969/j.issn.1000-2561.2020.11.020 Abstract ( 174 )   HTML ( 10 )   PDF (1213KB) ( 197 )   Rubber bark beetles are serious and difficult to control. In order to explore more effective field prevention and control methods, this study used a combination of “kraft paper+sticky insect glue+attractant” to design a sticky-capture device of rubber bark beetles. The trapping parameters including material of sticky-capture device, number of attractant pouch hanging, exposed areas of liquid medicine, and mutual spacing and suspension height of sticky-capture device were optimazed. Under the trapping of myrcene, 2-methyl-3-buten-2-ol, S-(-)-limonene, camphene and (S)-cis-verbenol, the total number of sticky-captures of the homemade sticky-capture tape against the rubber bark beetles was 554, 445, 341, 381 and 367. The total number of sticky-captures of the common sticky insect tape against rubber barks beetles was 260, 230, 179, 202 and 199. For myrcene, 2-methyl-3-buten-2-ol, and S-(-)-limonene, the total number of sticky-captures of the homemade sticky-capture tape was significantly higher than that of common sticky insect tape, showing better sticky-capture effect. The optimal number of bags when using the hanging bag method was two. The best exposure areas of liquid medicine was 6.6 mm 2, the best mutual spacing of the sticky-capture device was 50 m, and the best suspension hight was 2.5 m. The homemade sticky-capture device is superior to conventional trap device in weight, cost, and the number that can be trapped. For the prevention and control of rubber bark beetles, it has the characteristics of high efficiency, low cost, environmentally friendly and degradable, simple and easy to operate.
 Determination of Lethal Ability of Heterorhabditis bacteriophora H06 Strain Against the Larvae of Red Palm Weevil Rhyncophorus ferrugineus in Laboratory ZHONG Baozhu,LYU Chaojun,LI Chaoxu,YAN Wei,HUANG Shanchun,QIN Weiquan 2020, 41 (11):  2292-2296.  doi: 10.3969/j.issn.1000-2561.2020.11.0021 Abstract ( 342 )   HTML ( 12 )   PDF (1312KB) ( 244 )   To explore the feasibility of controlling Rhyncophorus ferrugineus using entomopathogenic nemotode Heterorhabditis bacteriophora H06 strain, the lethal effect and virulence level of entomopathogenic nemotode on the larvae of red palm weevil were tested in laboratory. The pathogenicity of different dosage and exposure time of H. bacteriophora H06 against 3 rd instar larvae of red palm weevil were determined by the micro-drop method, and the morphological characteristics of the infected larvae were also observed. H. bacteriophora H06 strain had a certain lethal effect to the 3 rd instar larvae of R. ferrugineus. With the increase of nematode inoculation dosage, the mortality rate of red palm weevil increased. Toxicity test results showed that LD50 value decreased with the exposure time. Meanwhile, with the increase of nematode inoculation dosage, the LT50 of red palm weevil larvae decreased gradually. Morphological observation showed that the infected larvae of the red palm weevil showed a process of sriffness, shrikage, browning, swelling and finally decay, and nematode was free from the larvae. The above result indicated that the nemotode strain H. bacteriophora H06 strain had some control effect on the lower instar larvae of R. ferrugineus in laboratory.
Post-harvest Treatment & Quality Safety
 Simultaneous Determination of 8 Plant Growth Regulator Residues in Banana by Using Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry in Combination with QuEChERS Metho-dology WU Xuejin,WANG Mingyue,MA Chen,ZHANG Qun,PANG Chaohai 2020, 41 (11):  2297-2304.  doi: 10.3969/j.issn.1000-2561.2020.11.022 Abstract ( 251 )   HTML ( 10 )   PDF (1553KB) ( 265 )   In order to determine the residue of plant growth regulators in banana, a method was developed for the simultaneous determination of 8 plant growth regulators residues (PGRs) in banana by using QuEChERS (quick, easy, cheap, effective, rugged and safe) purification coupled with ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Using acetonitrile containing 1% acetic acid (V/V) as extraction solvent, the samples was prepared by the modified QuEChERS method. The chromatographic separation of 8 target compounds was accomplished in an Agilent InfinityLab Poroshell 120 EC-C18 column using methanol and 5 mmol/L ammonium acetate-0.1% formic acid buffer solution as mobile phase by gradient elution at a flow rate of 0.25 mL/min in 10 min. The 8 target compounds were analyzed by using UPLC-MS/MS in selective reaction monitoring (SRM) mode and then were quantified by the matrix matched standard calibration curve method. The method evaluation was done by matrix-matched calibration with linearity ranging from 5 to 100 μg/kg with a correlation coefficient more than 0.999. The detection and quantification limit ranged from 0.03 to 0.6 μg/kg and 0.10 to 2.0 μg/kg, respectively. The average recoveries at three spiked concentration levels of 10, 20, 100 μg/kg for all target compounds in the samples were in the range of 73.5% to 107.2%, with relative standard deviations (RSD) not more than 11%. The method is simple, quick, convenient, sensitive, and can be applied to analyze 8 plant growth regulators in banana. This method will provide a reference for the residue detection of plant growth regulators in other fruits and vegetables.
 Analysis on the Quality and Aroma Components of Main Mango Fruits in Guizhou KANG Zhuanmiao,HE Fengping,HUANG Hai,LI Xiangyong,LIU Qingguo,ZHANG Yan,GONG Deyong,FAN Jianxin,HUANG Jianfeng,DANG Zhiguo,WANG Yirong,WU Xiaobo,LIU Rong 2020, 41 (11):  2305-2313.  doi: 10.3969/j.issn.1000-2561.2020.11.023 Abstract ( 239 )   HTML ( 9 )   PDF (1623KB) ( 282 )   In order to understand the quality characteristics of the main mango varieties in Guizhou, 12 quality indexes and aroma components of 5 mango varieties were analyzed. The results showed that the average fruit weight of the five mango varieties ranged from 380 to 898 g, the fruit shape index was 1.60 to 2.14, the edible rate was 72.10% to 77.74%, the water content was 82.06% to 85.10%, the total ash content was 1.30% to 1.70%, the crude fiber content was 0.90% to 1.10%, the soluble sugar content was 7.75 to 13.90 g/100 g, the soluble solid content was 11.05% to 17.10%, the total acid content was 0.120 to 0.233 g/100 g, the content of vitamin C was 0.0018 to 0.0073 g/100 g, the sugar acid ratio was 40.26 to 123.88, and the solid acid ratio is 61.30 to 153.39. There were 50 aroma components in the five mango varieties, and the main aroma components were terpenes. 14, 14, 21, 21 and 16 aroma components were detected in the Jinhuang mango, Guifei mango, Yuwen mango, Guiqi mango and Hongyu mango, while the content of terpenes was 56.34%, 73.95%, 82.47%, 97.32% and 64.16% respectively. The fragrance of the five mango varieties was mainly pine smell with little green, apple and lemon smell.
 Effects of Low Temperature Storage on Quality and Storability of ‘Songfengben’ Longan Fruit CHEN Jin,LIN Yixiong,LIN Yuzhao,LIU Jingyun,LIN Hetong,LIN Yifen 2020, 41 (11):  2314-2321.  doi: 10.3969/j.issn.1000-2561.2020.11.024 Abstract ( 347 )   HTML ( 12 )   PDF (1526KB) ( 239 )   This study investigated the effects of different storage temperatures on quality and storability of ‘Songfengben’ longan (Dimocarpus longan Lour. cv. Songfengben) fruit. The harvested longan fruits were selected, cleaned and dried prior to packaging with polyethylene bag (50 longans per bag), and then stored at (25±0.5)℃ and (3±0.5)℃, respectively. During storage, 150 longan fruits (3 bags) were sampled for measuring the indices of longan nutritional quality and storability. The results showed that, in comparison to the control longans storage at room temperature with (25±0.5)℃, low temperature storage at (3±0.5)℃ could effectively reduce longan fruits respiration rate, keep higher contents of longan pericarp pigments including chlorophyll, carotenoid, anthocyanin and flavonoid, as well as retain higher amounts of longan pulp nutrients like total soluble solids, total soluble sugars, sucrose, reducing sugar, and vitamin C. In addition, low temperature storage at (3±0.5)℃ could retard longan pericarp browning and pulp breakdown, lower the rate of weight loss from longan fruits, and keep higher percentage of commercially acceptable fruit. From the results it could be concluded that (3±0.5)℃ could be used as the recommended temperature for low temperature storage and transportation of ‘Songfengben’ longan fruits, which could keep the quality and prolong the shelf-life of ‘Songfengben’ longan fruits during postharvest storage.
Agricultural Ecology & Environmental Protection
 Single-wood Health Assessment in Casuarina Protection Forests at Different Distances from the Coastline LIU Hena,LI Maojin,WANG Yanyan,JIANG Chuanyang,LI Kunling,WU Chengzhen,CHEN Can 2020, 41 (11):  2322-2328.  doi: 10.3969/j.issn.1000-2561.2020.11.025 Abstract ( 257 )   HTML ( 6 )   PDF (1227KB) ( 195 )   Single-wood health assessment is an important part of forest health monitoring. Coast protect forest is one of the critical plantation ecosystems in China, which is damaged to some extent in a strong variation environment with intense differences from the ocean to the land. But, at present the research on the assessment of forest health in a single-wood scale and in different distances from the coast line is so scarce due to overlooking the health of the trees growing in the weakness of the ecosystem. In order to make up the gap, we took different Casuarina forests as the study objects, divided their distances into five gradients from near to far, which was from the forest edge facing the sea to the forest interior, and established a single-wood health assessment system including the indexes of root damage, crown deciduous degree, canopy transparency, crown overlap, crown dieback, canopy weight and crown deviation. The overall health of single-wood trees in the coastal Casuarina forest was poor with 17.78% unhealthy and only 4.44% in good health. The different gradients of the coastal Casuarina forest showed obvious significant from the coast forest trees to the interior ones. The unhealthy grade trees in the first gradient were up to 33.33%, which was significantly more than that in the second one (P<0.05), and there were no high grade trees. The unhealthy trees in the fifth gradient were significantly less than that in the third and fourth gradients (P<0.05) with 93.33% of the health and above grades. The study would lay a basis for the health management of coastal Casuarina protection forests.
 Flora Characteristics of Vascular Plants in Qingyunshan Nature Reserve of Wengyuan, Guangdong Province DU Xiaojie,XIE Chonglin,YU Xiaoling,DENG Shuangwen,YANG Xindong,CHEN Liubao,WANG Faguo,XING Fuwu 2020, 41 (11):  2329-2334.  doi: 10.3969/j.issn.1000-2561.2020.11.026 Abstract ( 268 )   HTML ( 10 )   PDF (1092KB) ( 399 )   Qingyunshan Provincial Nature Reserve is situated in southeast of Wengyuan County, Guangdong Province, China. Its plant species diversity was studied based on field investigation, literatures check and specimens collected. There were 1336 vascular plant species, including species, subspecies, varieties and forms, of which there were 132 taxa of lycophytes and ferns belonging to 62 genera and 24 families, and 6 taxa of gymnosperms belonging to 4 genera and 4 families, and 1198 taxa of angiosperms belonging to 588 genera and 148 families. The dominant and typical families of angiosperms are Lauraceae, Fagaceae and Aquifoliaceae et al. The vegetation has a certain transitional nature from Mid-subtropics to South-subtropics. According to the distribution characteristics of endemic species in China, this area is closely related to southern Hunan, northeastern Guangxi and southwestern Jiangxi, which reflects the consistency and integrity to the flora of Nanling Mountains. The plants species and vegetation types in Qingyunshan Provincial Nature Reserve are rich, in which 48 species are rare and endangered plants. In the light of the distribution features and protection status of rare plant resources in this nature reserve, it is suggested that some areas with more concentrated distribution of rare and endangered plants, such as Yuandong and Qingshankou, should be taken as priority protected areas.
Reviews
 The Development of Coconut (Cocos nucifera L.) Tissue Culture Technology in the Past 40 Years: a Review MU Zhihua,LI Zhiying,LIU Rui,FAN Haikuo 2020, 41 (11):  2335-2345.  doi: 10.3969/j.issn.1000-2561.2020.11.027 Abstract ( 365 )   HTML ( 14 )   PDF (1380KB) ( 393 )   Coconut tissue culture is an important technology for the future of the coconut industry. This paper has reviewed many valuable studies in the recent four decades. The importance of coconut tissue culture, differences and advantages of varies of explants (plumule, inflorescence, ovary), the influence of different medium compositions and environmental conditions were presented in detail. A brief summary of many protocols created worldwide and China has been made. Subsequently, the restrains of coconut tissue culture were identified and listed, and some suggestions were made to overcome the limits. This literature review could help the coconut tissue-culturists to further discover the potential of coconut tissue culture.
 Current Status of Chemical Fertilizer Application in Banana Plantation, Environmental Risks and Integrated Nutrient Management Practices ZHAO Fengliang,ZOU Ganghua,SHAN Ying,DING Zheli,WU Peicong,ZHANG Peng,ZHU Zhiqiang 2020, 41 (11):  2346-2352.  doi: 10.3969/j.issn.1000-2561.2020.11.028 Abstract ( 259 )   HTML ( 15 )   PDF (1239KB) ( 296 )   Although fertilizer application has been important for increasing agricultural productivity, excessive application can negatively impact crop production and lead to environmental pollution. This review analyzed the current status of banana production and fertilization application in major banana-producing countries as well as problems associated with banana fertilization. This paper also summarized non-point source pollution caused by excessive fertilization in banana plantations, and proposed countermeasures to reduce environmental risks integrated nutrient management practices in banana plantations, including fertilization principles, soil acidity remediation, soil testing-based fertilization, and emerging fertilizers and technologies. The aim of the review is to provide useful references for scientific fertilization and non-point source pollution prevention and control in banana plantations.
 Research Progress on the Physicochemical Properties and Exploitation of Mango Kernel Oil TU Xinghao,MA Huifang,WEI Fang,XIE Ya,LYU Xin,CHEN Hong,DU Liqing 2020, 41 (11):  2353-2363.  doi: 10.3969/j.issn.1000-2561.2020.11.029 Abstract ( 267 )   HTML ( 8 )   PDF (1300KB) ( 272 )   Mango kernel, a byproduct of mango processing, is of a fat content 9.0%~13.1% (dry basis). The extracted kernel oil is a high quality oil, which has high nutritional value and development prospect. In this paper, the research progress of mango kernel oil in recent years were summarized from three aspects: the physiochemical index, lipid composition, exploitation and utilization. By comparing with the triglyceride components of cocoa butter and cocoa butter alternatives, the problems in the research of mango kernel oil were clarified and reasonable suggestions were given. It is hoped to promote the further development of mango kernel oil research and provide theoretical guidance and basis for the research and industrial development of mango kernel oil.