Litchi (Litchi chinensis Sonn. cv. 'Feizixiao') has a high market value. However, its value declines during postharvest storage because its quality deteriorates, and its pericarp turns brown. Therefore, safe and effective ways of improving litchi quality and inhibiting postharvest browning are required. In this study, 5-aminolaevulinic acid (5-ALA) and thidiazuron (TDZ) were applied to litchi fruit before harvest to determine their relative effects on litchi colour and postharvest storage characteristics. The results showed that preharvest 5-ALA application significantly increased postharvest fruit weight, anthocyanins, total phenol, vitamin C and antioxidant activity relative to those in the untreated fruits. Compared with the control, TDZ significantly increased fruit weight but inhibited anthocyanin accumulation and did not significantly alter antioxidant activity. Both preharvest treatments significantly reduced the browning index, the relative leakage rate and polyphenol oxidase activity after 6 d of storage. A membership function analysis indicated that preharvest 5-ALA application was the most beneficial for postharvest storage whereas TDZ treatment was relatively less effective. Preharvest colour promotion was preferable for improving litchi quality and inhibiting postharvest browning.

以油梨(Persea americana)抗根腐病品种‘Duck7’的茎段为试验材料,WPM为基础培养基,采用Design-ExpertV8.0.6软件设计油梨不同快繁阶段的植物生长调节剂配比,通过观测相关指标,结合植物生长调节剂间互作效应,推测出不同生长阶段的最佳植物生长调节剂组合并进行验证.结果 表明:(1)油梨最佳不定芽诱导培养基为WPM+0.13 mg·L-1TDZ+1.72 mg·L-16-BA+0.1 mg·L-1NAA,经验证,该配方的不定芽诱导率达95％,比原设计组合最高诱导率高出1.67％;(2)油梨最佳不定芽增殖培养基为WPM+1.73 mg·L-16-BA+0.2 mg·L-1NAA,经验证,该配方的增殖系数达3.18,比原设计组合最高增殖系数高出0.03;(3)油梨最佳生根培养基为1/2MS+0.5mg·L-1 IBA+0.34 mg·L-1 NAA+1 g·L-1活性炭,经验证,该配方的生根率达66.67％,比原设计组合最高生根率高出5％.综上所述,本研究探索出了‘Duck7’油梨的离体快繁技术,可为油梨抗根腐病砧木的批量扩繁提供技术参考.

This study investigated the desuckering effect of a 2:1 mixture of KH2PO4 (KDP) and paclobutrazol (PBZ) and its influence on banana mother plant growth, fruit yield, and quality. The mixed reagent was injected into suckers sprouting from 5-month-old banana (Musa paradisiaca AA) plants after removing the above-ground part of the suckers. Compared to control plants, treatment with the KDP/PBZ mixture significantly reduced superoxide dismutase, peroxidase, and catalase activities but increased malondialdehyde content at sucker growth points and in adjacent tissue after 1 d. There was evidence of damage to the cellular structure at sucker growth points after 2 d of treatment, with an increase in intercellular space as well as rupturing and death of most cells. All suckers died 3 d later, resulting in a mortality rate of up to 100%, and there was no subsequent regrowth of the dead suckers; indicating that a single application of the KDP/PBZ reagent is a viable desuckering practice. Relative to the control, the treatment of suckers also indirectly increased the height and stem diameter of mother plants, which was associated with increased fruit yield (yield per plant, weight per hand, weight per fruit, transverse and longitudinal diameters of fruit fingers) and enhanced nutritional quality of the fruits (edible fraction, soluble solid, titratable acidity, vitamin C, and moisture content). These results indicate that a 2:1 KDP/PBZ mixture can effectively remove banana suckers while improving fruit yield and the quality of the mother plant. The proposed desuckering practice can help to address challenges associated with banana production such as difficulties in desuckering and preventing sucker regrowth, minimizing fertilizer waste, and high costs.

This paper first identified the cold resistance of 38 varieties of avocado by determining the semi-lethal low temperature (LT 50 ) of the leaves using an electrical conductivity method in combination with a logistic function, and then analyzed the correlation between the LT 50 of 27 varieties and the capacitance measured 9 different parts of the leaves in vivo, to explore the relationship between the cold resistance of various avocado varieties and the capacitance of different parts of avocado leaves, so as to develop a new method for highly effective identification of cold resistance of living avocado varieties. The results showed that various avocado varieties’ LT 50 was significantly positively correlated with the capacitance of some parts of leaves, showing that the cold resistance of various avocado varieties was negatively correlated with the capacitance of various leaf parts. The results of mango variety trials conducted for comparison is coincident with the theoretical conclusion reached in the identification of the cold resistance of the avocado. So as to the study of the cold resistance of avocado and mango varieties, the capacitance of live mature leaves measured in the field can be used as a new method for the judgment of cold resistance. Highlight A new method for identification of avocado cold resistance through measuring the capacitance of different parts of leaves was developed. This method are simple, quick and efficient.