Study On The Mechanisms Of Endodormancy Induction And Short-term Heating Releasing Dormancy In Peach (Prunus Persica) Bud

Two-year-old peach trees of cv Chunjie and Qingzhoudongxuemitao, and six-year-old nectarine trees of cv Shuguang, grafted on Qingzhoudongxuemitao rootstock, were planted in the fruit experimental orchard of Shandong Agricultural University in order to study the mechanisms of endodormancy induction and short-term heating releasing endodormancy in peach buds. The main results are as follows:1 The mechanism of endodormancy induction of'Chunjie'and'Qingzhoudongxuemitao'peach buds.1.1 Peach plant was very sensitive to short day and/or low temperature, which could induce growth cessation, dormancy and freezing resistance of peach plant, but their mechanisms were different from each other in this process. Short day induced dormancy of peach plant then freezing resistance, whereas low temperature first induced freezing resistance then dormancy. Under seasonal changes, short day induced dormancy of peach bud, then low temperature promoted the dormancy development. Compared with the short chilling requirement ecotype'Chunjie'peach, the long chilling requirement ecotype'Qingzhoudongxuemitao'peach was more responsive to seasonal changes/short day/low temperature, resulting in earlier growth cessation, cold acclimation and dormancy development.1.2 The dormancy induction of peach tree was regulated by balanceable change of ABA and GA3, not by ABA or GA3 alone, and there is an important control point in this balanceable change, the peach tree was induced to enter the endodormancy status when the ratio of GA3 and ABA was lower than this control point, whereas the peach plant bud was not induced to development dormancy.1.3 Ca²⁺ played a crucial role in growth cessation, dormancy induction and freezing resistance development of peach plant, and it could make effects as messenger in signal transduction of short day and low temperature.1.4 During the dormancy induction, the frequency of the plasmodesmata in the apical meristem of peach bud decreased, and the plasmodesmal channel became narrow, and the sphincters were found in the enter of the plasmodesmal channel. Finally, the intercommunion of cell and cell intermitted, and the function of the apical meristem as a whole was lost during the deep dormancy.1.5 The signal of dormancy induction could not transfer from the dormant shoot to the active shoot in the same peach tree, and not induced the active shoot of the same tree to enter the dormancy.1.6 The water content and status, membrane permeability, starch and soluble sugar content and respiration significantly changed during the dormancy induction. Along with dormancy inducing, the water content, the ratio of the free water and the bound water and membrane permeability rapidly decreased, and starch and soluble sugar content fleetly increased. Meanwhile, respiratory intensity gradually declined, and respiratory pathways changes. The TCA capacity of protein and fat sharply rised, and the EMP-TCA capacity erratically changes, but the HMP capacity gradually dropped, in contrast, the total capacity of the other respiratory pathways increased by degrees.2 Effects of short-term heating at 40℃,45℃and 50℃on the breaking endodormancy of'Shuguang'nectarine buds.2.1 Short-term heating at 40℃significantly restrained the endodormancy release in P. persica, but...