半干旱雨养农业区春小麦水分利用效率变化及其年型划分

Variation of Water Use Efficiencies and Climatic Year Patterns for Spring Wheat in Semi-arid Rainfed Region

如何利用有限的水分获得更多的作物产量是干旱半干旱农业发展的目标和挑战。以半干旱雨养农业区春小麦为突破口,研究了其在不同气候年型下对不同来源的水分利用效率,以选择适宜种植春小麦的气候年型,旨在为半干旱雨养农业区农民种植决策提供依据。以半干旱雨养农业区的典型代表区域定西市安定区为例,采用定西地面气象观测站与定西农业气象试验站1987—2011年的观测资料,分析了当地春小麦对不同来源水分的利用效率及其影响因素。结果表明,定西市安定区1987—2011年25 a间春小麦主要生育期气候存在暖干化趋势,但春小麦降水利用效率和播前土壤水分利用效率均未出现明显的变化。播前土壤水分是影响生育期降水利用效率的主要因素,但生育期大气干湿状况对降水利用效率也有影响。同时,大气干湿状况影响播前土壤水分利用效率,而播前土壤水分的高低对大气干湿状况与播前土壤水分利用效率的关系亦有影响。根据播前土壤水分、主要生育期大气干湿状况、春小麦历年产量,可将半干旱雨养农业区(定西市安定区)春小麦生长的气候年型划分为5个,分别为高产年份、中高产年份、中产年份、中等偏低产量年份、低产水平年份。不同气候年型下,降水利用效率和播前土壤水分利用效率不相同。水分限制情形下,在春小麦达到最大水分利用效率之前,越是适宜的环境,越有利于提高春小麦水分利用效率。在相对适宜的气候条件下,春小麦对播前50 cm土壤水分的利用效率要高于对主要生育期降水的利用效率。因此,选择播前土壤水分高、大气湿润的气候年型种植春小麦能够保证获得较高产量。

How to use limited water to obtain more crop yield is the goal and challenge of the development of arid and semi-arid agriculture.Spring wheat in semi-arid rainfed agricultural areas was taken as the potential breakthrough point for studying the water use efficiencies of different sources under different climatic year patterns to select suitable climatic year types for planting spring wheat and provide a basis for farmers'planting decisions in semi-arid rainfed agricultural areas.Anding District,Dingxi,a typical representative area for semi-arid rainfed agriculture,was taken as an example,the observation data from Dingxi surface meteorological observation station and Dingxi agricultural meteorological experimental station from 1987 to 2011 were used to analyze the utilization efficiencies and influencing factors of different sources of water used by local spring wheat.The results showed there was a warming and drying trend during spring wheat growing season from 1987 to 2011.However,There was no significant change in precipitation utilization efficiency and soil water utilization efficiency before sowing of spring wheat.Soil moisture before sowing is the main factor affecting the utilization efficiency of precipitation during the growth period,but the dry and wet conditions of the atmosphere during the growth period also have an impact on the utilization efficiency of precipitation.Meanwhile,air moisture condition during spring wheat growing season had great impact on soil water use efficiency before sowing,but the soil water content before sowing also affected the relation between air moisture condition during spring wheat growing season and soil water use efficiency before sowing.According to soil moisture before sowing,the atmospheric dry and wet conditions during the growth period,and the annual yield of spring wheat,the climatic patterns of Anding could be classified into five types,namely high yield,medium high yield,middle yield,medium low yield,and low yield.Precipitation utilization efficiency and soil water utilization efficiency before sowing varied under different climate year types.Under limited water condition,the more optimal environment could lead to higher spring wheat water use efficiency.Under relatively suitable climatic conditions,the utilization efficiency of spring wheat for soil moisture at 50 cm before sowing was higher than that for precipitation during the growth period.Choosing a climate year with high soil moisture and humid atmosphere before sowing spring wheat can ensure higher yields.