Effect Of The Temperature Changes In Winter On The Dormancy And Buding Of ’Dangshansuli’ Pears Plant

Dormancy is an important research content of cultivation physiology for deciduous fruit trees, and one of the hot topics of pomological development biology, which related closely to economic production. Winter dormancy and bud germination of ‘Dangshansuli’ pear are directly responsible for the annual yield. Due to the warming climate in winter, the lower winter temperature could not halt ‘Dangshansuli’ pear from dormancy, some phenomenons appeared, such as orderless pear blossom, production decreasing and quality declining in some areas of Yunnan province. Therefore, exploring the characteristics of dormancy and needs of physiological chilling is not only crucial for the agricultural production, but also a preservation and reproduction of species.Through rational construction of greenhouse on top of the mature ‘Dangshansuli’ pear trees and automatic temperature control measures causing temperature changes (3°C higher than that in the open field, the same as follows), the effect of temperature changes on the ‘Dangshansuli’ pear tree dormancy process, index of bud germination, bud germination rate and endogenous hormone content were investigated and the requirement of physiological chilling were measured.The main results of this study were represented as follows:1、Comparing to the case of the open field, the increased winter temperature delayed the dormancy of ‘Dangshansuli’pear for about6days, but the dormancy release occurred about4to5days earlier, the temperature changes in winter resulted in the direct period of deep dormancy without deepening stage of dormancy. During the dormancy period, the bud size of ‘Dangshansuli’ pear was not affected by the temperature changes, however, after dormancy, the bud size under treatments was significantly larger than that of untreated controls.2、W arming winter significantly affected on the content of IAA, GA3, ZR and ABA in the flower buds of ‘Dangshansuli’ pear but not the leave buds. As the increasement of temperature, the incidence of significant difference of IAA, GA3and ZR also raised. When the temperature increased by2.42and3.54°C, there was a significant difference in ABA.3、In most cases of winter warming, the ratios of ZR/GA, ABA/GA and ABA/IAA were significantly lower than those of the open fields, suggesting that winter warming was disadvantageous for flower formation.4、During the hibernation of ‘Dangshansuli’ pear, as the accumulation of low temperature. The ABA content in flower and leaf bud reached the summit in the deep dormancy period and began to decrease before germination. The content changes of GA3, IA and ZR were just the opposite.5、Winter warming resulted in a earlier blooming of germination of flower bud of6days and4～5days of leaf bud. It also affected the the survival of flower bud, but not the leaf bud.6、Winter warming exhibited different levels of effects on the germination of ‘Dangshansuli’ pear flower bud. Before1st April, the germination rate of the flower buds were Treatment1> Treatment2> CK, after1st April, the germination rate of the flower buds were Treatment2> Treatment1> CK, the germination rate of the leaf buds were Treatment1> Treatment2> CK.7、The7.2°C,0～7.2°C and Utah models were used to measure the requirement of the physiological chilling. The results showed that the requirements of ‘Dangshansuli’pear flower chilling were2070h after7.2model,1051h after0～7.2model and2198h after0-7.2model, while in the leaf buds,2198h after0-7.2model,1126h after7.2model,857h after Utah model,...