Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2021, Vol. 42 ›› Issue (10): 2986-2992.DOI: 10.3969/j.issn.1000-2561.2021.10.032

• Post-harvest Treatment & Quality Safety • Previous Articles     Next Articles

Relativity Analysis Between Characteristic Parameters of Off-season Longan Abscission and Its Fruit Removal Force

YANG Ziqin1, LI Jianguo2, ZHANG Lei1, LI Songgang1, HONG Jiwang1, HUANG Xuming2,*()   

  1. 1. Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences / National Center for Crops Varieties Improvement, Haikou, Hainan 571101, China
    2. College of Horticulture, South China Agricultural University / State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangzhou, Guangdong 510642, China
  • Received:2020-12-14 Revised:2021-02-04 Online:2021-10-25 Published:2021-11-25
  • Contact: HUANG Xuming


Pre-harvest fruit abscission phenomenon is intensive in off-season longan in Hainan, China, which seriously restricts the development of the off-season longan. Pedicel detaching force or fruit removal force, reflecting the separation status of the abscission zone, has been adopted as a direct index reflecting the process of fruit abscission. However, there has been no report about its use in longan. The purpose of our study was to evaluate the use of pedicel detaching force to reflect fruit abscission in off-season longan and clarify its correlation with availability of carbohydrates, fruit respiration rate and activities of wall-degrading enzymes in the abscission zone. Small clusters of fruit were harvested and pedicel detaching force was measured using DS2-1000 gf or DS2-5000 gf force gauges every day. At the same time, correlation of various physiological parameters with pedicel detaching force was analyzed. The pedicel detaching force of the off-season longan of ‘Chuliang’ ranged between 0 and 3000 gf. When it became less than 1000 gf, the fruit was doomed to abscise. The cumulative abscission rate was significantly and negatively correlated to pedicel detaching force, with a coefficient of -0.948 (P=0.000). Total sugar and starch content in fruit was significantly and positive correlated to pedicel detaching force with a correlation coefficient of 0.942 (P=0.005) and 0.952 (P=0.003), respectively. A moderate positive bud insignificant correlation was found between respiratory oxygen consumption and pedicel detaching force (r=-0.807, P=0.099). Activity of cellulase and β-mannanase in the abscission zone was negatively correlated to pedicel detaching force, with a correlation coefficient of ?0.936 (P=0.019) and -0.954 (P=0.002), respectively. The results showed changes in pedicel detaching force could be used to reflect the process of fruit abscission. Fruit abscission was accompanied by significant decrease in pedicel detaching force, which was highly correlated with carbohydrate availability and cell wall degrading enzyme activity in the abscission zone, and high fruit respiration consumption may accelerate the process of fruit abscission.

Key words: longan, fruit removal force, fruits, abscission

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