作为西南地区主要的水稻产区,成都平原近年来面临日益严重的干旱问题.为确定该地区水稻最适宜的播种时期,提高抗旱能力,本文以广汉地区为例,采用气候倾向率法分析1991-2020年不同播期水稻生育期的气候资源特征,并通过作物水分亏缺指数(Crop Water Deficit Index,CWDI)评估水稻生育期的干旱程度.结果表明,近30 a来研究区各播期水稻的气候特征均表现为日照减少、日均温上升、降水量增加的趋势.随播期推迟,水稻全生育期日照时数整体减少,日均温、降水量均呈上升和增加趋势.CWDI随水稻发育逐渐减小,各播期水稻在生育前、中期缺水率较高.不同播期水稻生长期内均以轻旱、中旱为主,其次是重旱,特旱最少.研究区3月下旬至4月初的气候资源配置最优,是最适宜水稻播种的时期;3月上旬及中旬播种应选择抗旱品种,而4月中下旬播种则需防范重旱对作物需水期的影响.
Analysis of climatic resources and drought characteristics during rice growth stages with different sowing dates in Chengdu plain:A case study of Guanghan
As a major rice-producing area in Southwest China,the Chengdu Plain has faced increasingly severe drought problems in re-cent years.In order to determine the most suitable sowing date for rice in this region and improve the drought resistance,this paper takes Guanghan area as an example,and adopts the climate tendency rate method to analyze the characteristics of climate resources at the rice growth stages for different sowing dates from 1991 to 2020,and evaluates the degree of drought at different growth stages of rice at growth stages by using the Crop Water Deficit Index(CWDI).The results show that the climatic characteristics of rice for different sowing dates in the study area over the past 30 years showed a trend of decreasing sunshine,increasing mean daily temperature and in-creasing precipitation.With the delay in sowing,the number of sunshine during the whole life cycle of rice decreased,and the average daily temperature and precipitation both increased.The CWDI values gradually decreased with rice development,and the water deficit rate was higher at the first and middle stages for each sowing date.Light and moderate drought,followed by severe drought,and excep-tional drought were observed during the growing stages of rice for different sowing dates.From late March to early April was the most suitable period for rice sowing in the study area,and drought-resistant varieties should be selected for sowing in early and mid-March,while sowing in mid-to late-April people should guard against the effects of severe drought on the water demand period of the crop.
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