Elucidation of the mechanism of occurrence of chilling requirement induction stage of dormancy

在桃需冷量诱导期，研究了人工打破休眠的调控和需冷量的遗传控制。1)高低温品种地上部基部侧芽7月上旬进入休眠，9月进入深休眠。氰氨化钙处理提高了休眠诱导期的萌芽率。温度和补光均影响休眠诱导的时间。2）低温品种在低温350 h后即可正常开花，开花率高。在这些品种中，对温度的敏感性的立即增加的萌芽是早期萌芽和开花的可能原因。3)不同品种接穗的需冷量不同，接穗的萌芽和开花也不同。砧木需冷量对叶芽萌发的时间和速率有影响，但对花芽的萌发无影响。4)高温对胚囊发育有不利影响。5)氰氨和氰氨钙对打破休眠的效果优于芳基二硫酸酯。但在深休眠期，药效降低。6)从休眠期和休眠后的叶片和花蕾中提取mRNA，采用差减法进行分析。观察到几个基因在休眠和休眠后阶段之间具有不同的转录量，并且包括与细胞周期调控相关的基因。7)高低温品种‘白凤’与低低温品种杂交的幼苗表现出比‘白凤’更少的低温。

Artificial regulation of breaking dormancy and genetic control of chilling requirement were investigated at induction stage of chilling requirement in Peach. 1)Lateral buds of basal position in shoot in high-chill cultivars entered into dormancy early July, and get into deep dormancy in September. Ca-cyanamide treatment enhanced bud break even at induction stage of dormancy. Temperature nor supplemental lighting affected the timing of induction of dormancy. 2)Low-chill cultivars could burst at high percentage and flowered normally even after only 350 chilling hour. In these cultivars, the immediate increase of sensitivity to temperature for bud burst is a possible reason of early bud burst and flowering. 3)Bud break and flowering largely depended on the chilling requirement of scion cultivar. The chilling requirement of rootstock affected the time and rate of bursting of leaf buds, but not flower buds. 4)High temperature adversely affected the development of embryo sac. 5)Cyanamide and Ca-cyanamide were more effective than Aryl-disulfate in breaking dormancy. However, the efficacy reduced at deep dormant stage. 6)The mRNA extracted from the leaf and flower buds at dormant and post dormant stages, was analyzed subtraction method. Several genes having different amount of transcription between dormant and post dormant stages were observed, and the gene related to the regulation of the cell cycle was included. 7)Crossed seedlings between high-chill 'Hakuho' and low-chill cultivars showed less chilling than 'Hakuho'.