Abstract:

Crop water surplus deficit index (CWSDI) is one of important indexes to distinguish drought degrees of crop. So the analysis of temporal and spatial distribution of CWSDI is with realistic significance to guide the reasonable distribution of crop and scientific and effective irrigation. Based on the observation records during the growing periods of spring maize and daily precipitation, temperature and wind speed data at 24 weather stations of central Inner Mongolia and so on during 1971-2015, the water requirement of crop was calculated by using Penman-Monteith equation. Combined with the effective precipitation, the water surplus deficit was calculated. And on this basis the temporal and spatial distribution characteristics of CWSDI of spring maize in central Inner Mongolia were analyzed quantitatively. The results showed that CWSDI during the growth period of spring maize in central Inner Mongolia presented a fluctuant change of falling first and then rising. CWSDI of crop appeared weak dropping trends in the early stages and the late stages of growth in central Inner Mongolia during 1971-2015, while it appeared rising trend in the middle stages, and the rising trend was obvious from the tasselling to milk-ripe stage of spring maize, especially it reached significant test of 0.05 level after the 1990s, which indicated that CWSDI increased in the critical period of water requirement of spring maize. The mutation of CWSDI from the tasselling to milk-ripe stage happened in 1991. In space, CWSDI of spring maize presented a zonal distribution with higher in the north and lower in the south of central Inner Mongolia, which was related with precipitation distribution with more in the south and less in the north.

Key words: water requirement, water surplus deficit index, temporal and spatial distribution characteristics, spring maize

摘要：

水分亏缺指数是判识作物干旱程度的重要指标之一，分析作物水分亏缺指数时空变化规律可为作物合理布局和科学有效灌溉提供理论依据。基于内蒙古中部地区24个气象站1971—2015年降水、气温、风速等逐日气象观测数据和春玉米生育期观测与调查资料，以Penman-Monteith模型为基础计算春玉米需水量，并结合作物有效降水量，定量分析春玉米水分亏缺指数的时空分布特征。结果表明，内蒙古中部地区春玉米生长季内水分亏缺指数呈“高、低、高”的波动变化；近45 a来，春玉米水分亏缺指数在生育前期和后期呈下降趋势，而在生育中期则呈上升趋势，且抽雄-乳熟期的水分亏缺指数上升趋势明显，1990年代以后上升趋势达到显著性水平，说明水分亏缺指数表现出向春玉米需水关键期增加的趋势，并在1991年发生显著突变；空间上，春玉米水分亏缺指数呈带状分布，且呈北高南低的分布格局，这与该区降水量南多北少的分布特征有关。

关键词: 需水量, 水分亏缺指数, 时空特征, 春玉米