云南省近50年水稻抽扬期低温冷害演变特征分析

Evolutionary characteristics of rice chilling damage in period of head sprouting and anthesis in Yunnan province in recent 50 years

采用云南省1960—2009年逐日平均气温数据,按照《云南省水稻抽扬期低温冷害业务标准》提取出这50 a中云南省水稻抽扬期发生低温冷害的天气过程,并进行冷害分级,基于Arc GIS绘制出各年代冷害发生的频率分布,再分地域研究其强度特征.采用线性趋势法、累积距平曲线等分析近50年云南省水稻抽扬期低温冷害的时间变化特征,以期揭示水稻抽扬期冷害的演变规律.结果表明:1960—2009年,云南省水稻抽扬期低温冷害的主要发生区域集中在昭通市和曲靖市,昭通市发生冷害程度最重,保山市的龙陵县也为多发地区;从时间变化趋势上看,水稻抽扬期不同程度的低温冷害发生日数均趋于减少;从站数比和其累积距平曲线变化上看,20世纪70年代冷害的发生范围最大,频率最高,90年代则为少发阶段,从2000年之后,冷害集中暴发,暴发速度快、强度大,到2008年才有所缓和.

Based on the daily temperature data of Yunnan province during 1960 to 2009,the rice chilling process was extracted and graded for recent 50 years according to the operating guideline of rice chilling damage in period of head sprouting and anthesis in Yunnan province.The frequency distribution of rice chilling damage in each decade was drawn by ArcGIS,then the chilling damage strength characteristics was studied geographically.The methods of linear trend and cumulative anomaly curve were used to reveal the evolution features of rice chilling damage in period of head sprouting and anthesis in Yunnan province in recent 50 years.Results showed that the rice chilling damage mainly occurred in Zhaotong,Qujing and Baoshan s Longling county,with Zhaotong as the most injured city.Generally,the total days of rice chilling damage showed a decreasing trend for the past 50 years.However,analysis of the ratio of stations with rice chilling vs.total stations and cumulative anomaly curve indicated that the 1970s had rice chilling damage with the largest range and the highest frequency,while the 1990s had the least rice chilling damage,then chillings occurred intensively in years after 2000,and eventually decreased in 2008.