美味系猕猴桃越冬冻害指标

通过对1991—2020年越冬期灾害调查、历史灾情查阅和专家评估，初步建立美味系猕猴桃越冬冻害症状及对应指标的3级评价标准。基于对美味系猕猴桃陕西及河南4个主栽县28例灾害个例致灾因子的主成分分析和K-means聚类分析，构建了美味系猕猴桃越冬冻害的综合指标及分级标准，并用3个主栽县资料进行验证。结果表明:美味系猕猴桃越冬冻害轻度、中度、重度发生的低温指标（T_D）分别为-12.0℃ < T_D≤-8.0℃，-15.0℃ < T_D≤-12.0℃，T_D≤-15.0℃；综合气候致灾因子包括过程极端最低气温（X₁）、-8.0℃以下低温持续日数（X₂）、-8.0℃以下负积温的绝对值（X₃）、-8.0℃以下过程有害积寒（X₄）；美味系猕猴桃越冬冻害轻度、中度、重度发生的综合指标（I_h）分别为-2.08 < I_h≤0.82，0.82 < I_h≤2.15，I_h＞2.15；美味系猕猴桃越冬冻害低温指标及综合指标等级划分在3个县验证应用结果均与实际情况基本相符。研究成果可为我国美味系猕猴桃越冬期冻害的防御和评价、产业布局优化、引种等提供参考依据。

Freezing Injury Indicator of Tasty Kiwifruit During Overwintering Period

China has the largest artificial planting area of kiwifruit, of which 67% is tasty kiwifruit. Tasty kiwifruit is mainly distributed in the north foot of Qinling Mountains in Shaanxi Province (about 40% of the national kiwifruit industry scale), and Funiu Mountain and Tongbai Mountain in Henan Province (about 20% of the national kiwifruit industry scale). These two producing areas locate in the northern edge of China's kiwifruit planting area, where the risk of overwintering freezing injury is high to cause great economic losses to fruit farmers. Therefore, it is especially important to study the freezing injury indicator of tasty kiwifruit for the introduction and expansion of tasty kiwifruit, disaster prevention and mitigation, and stable development of the industry.Through disaster investigation, expert interview, data research and other methods, 7 large-scale freezing injury cases of tasty kiwifruit in 1991, 2002, 2007, 2009, 2011, 2015 and 2020 are selected. The disaster cases of four counties, namely Huyi, Zhouzhi, Meixian and Tongbai are used as samples. The critical occurrence indicator of the overwintering freezing injury of tasty kiwifruit is determined as -8.0 ℃. The low temperature indicator (T_D) of mild, moderate and severe freezing injury of tasty kiwifruit are determined as follows: -12.0 ℃ < T_D ≤ -8.0 ℃, -15.0 ℃ < T_D ≤ -12.0 ℃, and T_D ≤ -15.0 ℃. Four factors are defined as: Winter minimum temperature (X₁), days of low temperature below -8.0 ℃ (X₂), absolute value of negative accumulated temperature below -8 ℃ (X₃), and process harmful accumulated cold below -8 ℃ (X₄). Using principal component analysis and K-means clustering analysis, the comprehensive indicator (I_h) of tasty kiwifruit overwintering freezing injury is constructed, and the ranges of I_h for different levels of freezing injury are as follows: -2.08 < I_h ≤ 0.82 for mild freezing injury, 0.82 < I_h ≤ 2.15 for moderate freezing injury, and I_h>2.15 for severe freezing injury. The indicators mentioned above are verified by the freezing injury cases of tasty kiwifruit in Changan, Wugong and Xixia counties. The results show that low temperature indicators and comprehensive indicators of overwintering freezing injury of tasty kiwifruit are basically consistent with the actual situation. The results can support the prevention and evaluation of the freezing injury of tasty kiwifruit during overwintering period, and also can provide reference for industrial layout optimization and introduction of tasty kiwifruit in China.