东北地区春玉米生长季农田蒸散量动态变化及其影响因子

Dynamic Change of Evapotranspiration and Influenced Factors in the Spring Maize Field in Northeast China

利用大型称重式蒸渗仪对东北春玉米田蒸散量的观测结果,分析玉米生长季蒸散量的分布特征及其影响因子。结果表明:东北春玉米生长季(播种-成熟)农田蒸散量为362.3mm,日平均蒸散量为2.6mm·d^(-1)。从各生育期的分布情况看,播种-七叶期蒸散量较小,日平均蒸散量为1.4mm·d^(-1),占全生育期的11.7%;七叶期开始,日平均蒸散量逐渐增加,在大喇叭口-抽雄期达到最大,为4.3mm·d^(-1);抽雄-乳熟期总蒸散量最大,为97.2mm,占生长季蒸散量的26.8%。从月蒸散量分布看,7-8月累积蒸散量达207.0mm,占5-9月蒸散量的54.5%;5、6和9月蒸散量较少,分别占5-9月总蒸散量的11.6%、19.6%和14.3%。从逐小时蒸散量变化看,蒸散量日变化表现为早晚低、中午高的"单峰型"曲线特征。蒸散量与叶面积指数、太阳辐射、5cm地温、平均气温、最高气温、最低气温存在显著的线性正相关关系,与空气相对湿度和饱和差间呈显著的二次函数关系。叶面积指数是影响春玉米农田蒸散最主要的生物因子,5cm地温和太阳辐射是最主要的环境驱动因子。

Using the observed data of large-scale weighing lysimeter, the distribution characteristics and influenced factors of evapotranspiration（ET_c） in the spring maize field were analyzed. The results showed that the total ET_c was 362.3mm and the mean diurnal evapotranspiration was 2.6mm·d^（-1） during the whole growth period. From the distribution of the growth period, ET_c was low during the sowing to seven leaves stage, which the mean diurnal evapotranspiration was 1.4mm·d^（-1） and accounted for 11.7% of the whole growth period. It rose rapidly since the seven leaves stage, reached the maximum from big flare to heading stage（4.3mm·d^（-1））. The ET_cfrom heading to milk maturity was 97.2mm and the percentage was 26.8% of the whole growth period. From the distribution of the month, the ET_c from July to August was 207.0mm which accounted for 54.5% from May to September, but the ET_c of May, June and September were low, and the percentage was 11.6%, 19.6% and 14.3%, respectively. From hourly change of the evapotranspiration, it could be graphed as a line with a single-peak which occurred around noon with lower evapotranspiration observed in the morning and evening. The ET_cincreased significant linearly with increases in leaf area index, solar radiation, 5cm soil temperature, mean air temperature, maximum air temperature and minimum air temperature, while it responded to changes in relative humidity and vapor deficit in a quadratic curve manner with a pattern of first increased and then decreased. Leaf area index was the major biological factors and the 5cm soil temperature and solar radiation were the major environmental factors for evapotranspiration.