2,4-D在柑橘果实留树保鲜中的作用和可能机制研究

以‘锦橙’（Citrus sinensis Osbeck）为材料，比较2,4-D不同浓度、不同施用时期对锦橙果实落果率和品质的影响，同时研究2,4-D在柑橘果实留树保鲜中的可能机制。结果发现，在盛花后200 d（柑橘果实转黄期）施用20 mg • L-1的2,4-D，能显著降低柑橘果实留树越冬的落果率，且对果实品质无不良影响，果实能够留树保鲜50 d左右。研究还发现，2,4-D处理能延缓果蒂离层的形成，抑制细胞壁降解相关酶基因CX16、PG2、PME1、PME2的表达。综上所述，2,4-D能够用于锦橙果实留树保鲜，其主要机制可能是抑制细胞壁降解和离层形成。

Effects of 2,4-D on Keeping Citrus Fruit Fresh on Tree and the Underlying Mechanisms

In the present study，effects and underlying mechanisms of 2,4-D，applied at different concentrations and at various time points，on fruit dropping rate and fruit quality of Jincheng（Citrus sinensis Osbeck）were investigated. The results showed that exogenous application of 2,4-D at 20 mg • L-1 and at 200 days after full blooming could prominently reduce the fruit shedding rate，without influencing the fruit quality. It suggests that 2,4-D treatment could keep fruit fresh on tree for approximately 50 days. Moreover，2,4-D treatment was found to delay formation of abscission zone and down-regulated expression of genes encoding enzymes involved in cell wall degradation，such as CX16，PG2，PME1 and PME2. Our finding revealed that the potential mechanism responsible for keeping fruit fresh on tree by 2,4-D is ascribed to inhibition of cell wall degradation and abscission zone formation.