基于作物水分盈亏指数的昆明水稻生长季干旱特征及成因分析

基于昆明站点1952—2013年逐日气象观测资料,根据联合国粮农组织1998年推荐的PenmanMonteith公式计算了昆明站近62 a来逐日的参考作物蒸腾量、水稻生育期需水量,利用Mann-Kendall趋势检验法研究作物需水量变化规律,同时根据水稻的水分亏缺指数(CWDI),采用通径分析方法研究各气象因子对水分亏缺指数的影响。结果表明:近62年来昆明地区平均旬需水量为32.55 mm;水稻生长季内干旱分布明显不均匀,随着生长季的推进,干旱级别从轻旱到重旱,干旱发生最严重时期是黄熟生育阶段,在整个水稻生长季内,水稻水分盈亏指数均值为38.07%,表明水稻处于重旱状态;在水稻生育期变异系数研究中,水分盈亏指数变异系数均较小,在返青、分蘖、拔节、抽穗、乳熟和黄熟六个阶段中,变异系数分别为1.8%、1.9%、1.3%、1.1%、0.8%、和0.8%,表明昆明地区近年干旱等级变化较小;影响水分盈亏指数最大正相关因素为日照,最大负相关因素为水汽压。

Cause analysis and drought characteristics during rice growing season in Kunming based on crop water deficit index

Based on the daily meteorological observed data from 1952 to 2013 in the Kunming Station, the daily reference evapotranspiration (ET₀) and the rice water requirements in growing season during 62 years in Kunming Station has been calculated by the Penman-Monteith Formular recommended by the Food and Agriculture Organization (FAO) in 1998. Using the Mann-Kendall trend test method has researched the change regular of the crop water requirements. At the same time, the concept of crop water deficit index (CWDI) has been introduced. According to the water deficit index of rice, has researched the effects of each meteorogical factor to the water deficit index by using the path analysis method. The results showed that: In recent 62 years, the average ten days crop water requirements in Kunming Region was 32.55 mm. The drought distribution in rice growth season was obviously uneven. With the increase of the growth season, the drought grade was from light drought level to the heavy drought level, the most serious drought occurrence period was the ripening stages. In whole rice growing season, the average water deficit index was 38.07%, it indicated that rice was at the heavy drought status. In the research of the coefficient of variation, the variation coefficient of the water deficite index was total small. In the six growth stages as turnning green, tillering, jointing, heading, milk muturity and yellow muturity, the variation coefficients were 1.8%, 1.9%, 1.3%, 1.1%, 0.8% and 0.8%, respectively. It indicated that change of the drought grade was rather small in recent years in Kunming Region. The maximal positive correlation factor for affecting the water deficit index was the sunshine hours and the negative correlation factor was the water vapor pressure.