基于核桃生理特征变化的越冬冻害监测指标研究

Research on monitoring index of winter freezing injury based on physiological characteristic change of walnut

以新疆阿克苏地区2个主栽核桃品种的1年生枝条为试验材料,采用人工模拟低温的方式,测定分析不同低温及低温持续时间下枝条叶绿素荧光参数、质膜透性和可溶性糖含量的变化特征。结果表明:随着处理温度的降低,2个核桃品种枝条的基础荧光(Fo)呈先上升后缓慢下降趋势,光能转换效率(Fv/Fm)呈下降趋势,-18~-21℃的低温造成了枝条光系统Ⅱ(PSⅡ)的结构损伤;枝条的相对电导率随温度的降低及低温持续时间的延长呈不断上升趋势,且在-18~-21℃大幅度增加,根据相对电导率进行Logistic方程拟合得出2个核桃品种的半致死温度均在-22℃左右;枝条的可溶性糖含量随温度的降低呈先上升后下降趋势,且对-18~-21℃的低温较为敏感。结合低温模拟试验和越冬期冻害历史灾情资料,以-20、-22、-24℃及其低温持续时间分别构建了核桃越冬冻害不同等级的综合监测指标,为有效预警和防冻减灾提供科学依据和指导。

The annual branches of two main walnut cultivars in Xinjiang Aksu area were used as experimental materials,and the change characteristics of chlorophyⅡfluorescence parameters,plasma membrane permeability and soluble sugar content in branches under different low temperature and low temperature duration were measured and analyzed by using artificial simulation of low temperature.The results showed that with the decrease of treatment temperature,the basal fluorescence(Fo)increased first and then decreased slowly,and the light energy conversion efficiency(Fv/Fm)decreased.The low temperature between-18℃and-21℃caused the structural damage of photosystemⅡ(PSⅡ)in the branches;the relative conductivity of branches increased with the decrease of temperature and the increase of low temperature duration,and increased greatly between-18℃and-21℃.According to Logistic equation fitting,the semi-lethal temperature of two walnut varieties was about-22℃;the soluble sugar content of the branches first increased and then decreased with the decrease of temperature,and it was sensitive to the low temperature between-18℃and-21℃.Combined with low temperature simulation test and historical disaster data of freezing injury during overwintering period,comprehensive monitoring indexes of walnut winter freezing injury with different grades were constructed at-20,-22,-24℃and their duration,so as to provide basis and guidance for effective early warning,antifreeze and disaster reduction.