淮北平原夏玉米花期高温热害综合气候指标研究

Use of integrated climatic index to determine high temperature damage to summer maize at florescence in the Huaibei Plain

夏玉米花期高温热害气候指标及其分级标准,是灾害监测预警和田间调查与评估等工作的基础。为研究确定夏玉米花期高温热害气候指标,本文选取决定高温热害致灾程度的4个关键致灾气象因子:极端最高气温、日最高气温≥35℃的日数和日最高气温高于35℃的积害量及其期间的平均最小相对湿度,采用主成分分析法,构建1个高温热害综合气候指数(D)。通过聚类分析法,结合典型高温热害年减产率的修正和2013年定点跟踪调查夏玉米田块的减产率、秃尖率和植株受害症状等资料的验证,确定了高温热害的综合气候指数(D)不同等级及其阈值。结果表明,夏玉米花期高温热害可分为轻、中、重、特重4个等级,对应阈值分别为0.11<D≤0.21、0.21<D≤0.45、0.45<D≤0.72、D>0.72。综合气候指数(D)和高温热害减产率显著正相关,相关系数为0.967 1。花期高温热害主要危害雌雄穗,受害程度与秃尖率、籽粒与茎秆比等密切相关,相关系数分别为0.819 8和?0.872 7。淮北平原夏玉米花期高温热害综合发生频率约1.7年一遇,其中以中度与重度等级高温热害发生频率相对较高,分别高于15%与20%。在全球气候变暖的背景下,在品种选育、布局和栽培管理上,应选择抗高温的优良品种,或在高温热害发生期间,采取人工辅助授粉或喷洒药剂等措施减轻影响与危害。

Establishing climatic index and its garding standard to determine high temperature damage to summer maize at florescence is critical for disaster monitoring and early warning. It is also a critical element for field survey and assessment. Four key meteorological factors were selected using the principal component analysis method to build integrated climatic index for this purpose. The indexes included extreme maximum temperature, number of days with maximum temperature higher than 35 ℃, average minimum relative humidity of days with daily maximum temperature higher than 35 ℃ and accumulative temperature of days with daily maximum temperature higher than 35 ℃. An integrated climatic index for high temperature damage was established to determine the extent of high temperature damage to of summer maize at florescence in the Huaibei Plain by using principal component analysis. Cluster correction analysis combined with yield reduction rate in typical years of high temperature damage was used to amend gratification of the integrated climatic index for high temperature damage to summer maize at florescence. The integrated climatic index was further validated with field investigation results of bald tip rate, yield reduction rate and plant symptoms of summer maize in 2013. And the grades and their thresholds were obtained finally. Based on the results, high temperature damage to summer maize at florescence was divided into four grades of slight, moderate, severe, extreme severe, with respectively integrated climatic indexes （D） of 0.11 〈 D ≤ 0.21, 0.21 〈 D ≤ 0.45, 0.45 〈 D ≤ 0.72 and D 〉 0.72. A significant positive correlation was noted between integrated climatic index （D） and yield reduction rate in typically high temperature years, with a correlation coefficient of 0.967 1. High temperature damage at florescence of summer maize caused significant damage to ears and tassel. The extent of damage was closely related to the bald tip rate and ratio of grain to stem, with respective correlation coefficients of 0.819 8 and 0.872 7. The frequency of high temperature damage to summer maize at florescence was once every 1.7 years in the Huaibei Plain. The frequencies of moderate and severe grades of high temperature damage were higher than those of the other two grades, accounting respectively for over 15% and 20% of high temperature damage frequency. Under global warming, it was beneficial to use high temperature-resistant varieties for breeding, cultivation and over arrangement, and use supplementary artificial pollination, pesticides or other measures to mitigate the effect and damage of high temperature to summer maize.