西藏冬小麦需水关键期的降水变化趋势分析

Analysis of Precipitation Change Trend During Key Water Requirement Periods of Winter Wheat in Tibet

利用 196 1～ 2 0 0 0年西藏不同农业气候区旬降水量资料 ,分析了冬小麦生育期的降水特征及趋势变化。结果发现 ,半干旱农区冬小麦拔节 -孕穗期、抽穗 -乳熟期的降水变率较大 ,多数年份自然降水不能满足作物需水 ,水分亏缺严重。半湿润农区多数年份拔节 -孕穗期的降水少于作物需水量 ,而抽穗 -乳熟期相反 ,水分有盈余。过去 4 0年冬小麦抽穗 -乳熟期、全生育期的降水量 ,在半湿润农区呈较明显的增加趋势 ,而在半干旱农区 1980年以前呈减少趋势 。

Based on the data of ten days precipitation from 1961 to 2000 in the different climatic zones of Tibet, the characteristics and change trend of precipitation during growth periods of winter wheat were analyzed. The results showed that the precipitation variability was big during jointing to booting and heading to milk stage of winter wheat in the semi-arid agricultural zones, while the precipitation in the most of years could not meet water requirements of winter wheat. In the semi-humid regions the precipitation could not meet water requirement of winter wheat during heading to milk stage, but with a water surplus during heading to milk stage. In the last 40 years, the precipitation during heading to milk stage and whole growth period of winter wheat showed obviously increasing trend in semi-humid agricultural zones and in the semi-arid agricultural zones after 1981, but with a decreasing trend in the semi-arid agricultural zones before 1981.