Study on the evaluation method of cold hardiness in deciduous fruit trees and its application.

本研究首先建立了一种可靠、快速的评价某些落叶果树抗寒性的方法，为此，我们采用热电模块作为检测器进行热分析，使我们能够同时测量多个芽样。其次，在验证方法有效性的基础上，对柿子及其近缘种在休眠季节的驯化和脱驯化过程中的过冷特性进行了表征，并对其抗寒性进行了探讨。1)对附着在枝节上的柿子休眠芽进行热分析，检测到的两个放热温度与芽的致死温度不一致。当分离的芽被分析时，只检测到一个放热，并且与它们的致死温度一致。这一结果表明，应对离体芽进行热分析，以评价其抗寒性。枝条茎段的致死温度明显低于休眠芽的致死温度，这也表明需要对休眠芽进行抗寒性评价。2)对去芽鳞的解剖柿芽原基进行热分析，其放热温度低于完整芽的致死温度，说明柿芽鳞对全芽抗寒性没有任何保护作用，甚至降低了其过冷能力。3)不同水果品种间的热分析比较表明，苹果、梨和桃的休眠芽通过器官外冷冻存活，而葡萄和柿子的休眠芽通过真正的过冷存活。这些不同的抗冻机制似乎与芽的解剖特征有关。4)从芽休眠的角度研究了冬季气温对柿子抗寒性的影响。在休眠解除前，环境温度的高低对芽的抗寒性没有影响，而休眠解除后，不合时宜的温暖温度对芽的抗寒性有明显的降低。5)柿子品种和其他4种柿属植物在花蕾期前后最易受霜冻危害，但品种抗寒性的特异性主要表现在花蕾期后幼芽的抗寒性上。少

This study was aimed firstly to establish a reliable and rapid method of evaluating cold hardiness of some deciduous fruit species, for which we examined thermal analysis using thermoelectric modules as the detectors which enabled us to measure many bud samples at the same time. Secondly, after demonstrating the validity of the method, we characterized the supercooling characteristics of persimmon and its related species during acclimation and deacclimation processes in the dormant season and discuaaed the cold hardiness of this fruit species.1)When thermal analysis was conducted with dormant buds of persimmon attached to branch segments, two exotherms detected did not coincide with the lethal temperature of the buds. When the detached buds were analyzed, only one exotherm was detected and coincided with their lethal temperature. This result suggested that thermal analysis should be done with detached buds to evaluate their cold hardiness. Furthermore, lethal temperature of branch segm … More ents was substantially lower than that of dormant buds, which also suggested that cold hardiness should be evaluated on dormant buds.2)When dissected bud primordia of persimmon with their bud scales removed were thermal-analyzed, their exotherm temperature became lower than the lethal temperature of intact bud, indicating that bud scales of persimmon did not have any protective role to the cold hardiness of whole bud and even reduced its supercooling ability.3)Comparisons of thermal analysis between fruit species revealed that dormant buds of apples, pears and peaches survive freezing temperature by extraorgan freezing, while those of grapes and persimmons do so by real supercooling. These different freezing resistance mechanism among fruit species appeared to be related to the anatomical features of bud.4)The effect of air temperature in the winter on the cold hardiness of persimmon was examined in relation to bud dormancy. Before dormancy release, the ambient air temperature, either high or low, had on effect on the bud cold hardiness, while once the dormancy was released, untimely warm temperature decreased cold hardiness considerably.5)All the persimmon cultivars and other four Diospyros species examined were the most susceptible to frost damage at around the time of budburst, but the cultivar-or species-specificity in cold hardiness was expressed by the hardiness of young shoots developed after budburst. Less