覆膜棉田蒸散发日变化规律及其影响因子分析

Daily Variation of Evapotranspiration Rate and Its Influencing Factors in a Cotton Field under Mulch

田间蒸散发是西北干旱地区水文循环的重要组成部分,精确监测田间蒸散发量对该地区农田水量平衡计算和水资源评价具有重要的意义。为探究干旱地区棉田蒸散发量的动态变化规律及其影响因素,在新疆生产建设兵团炮台土壤改良试验站,利用LCpro+光合作用仪测量了膜下滴灌棉田田间蒸散发量。结果表明:棉花叶片蒸腾速率和膜间土面蒸发速率日内均呈现中午高、早晚低的单峰变化规律;棉花铃期到吐絮期期间棉花叶片日均蒸腾量为2.20mm,膜间土面日均蒸发量为0.16mm,单膜下棉田日均蒸散发量为2.21mm,蒸腾是土壤水分散失的主要方式;受灌水、气象等因素的影响,土壤温度和土壤含水率均呈现波动性变化;棉花叶片蒸腾速率和膜间土面蒸发速率与土壤温度在日内按正弦曲线变化,膜间土面蒸发速率与土壤温度的相关性较棉花叶片蒸腾速率更为显著;膜间土面蒸发量与土壤含水率的相关性也较棉花叶片蒸腾量显著。

Field evapotranspiration is an important part of the water cycle in the arid area,and the precise measurement of the field evapotranspiration has a vital significance for the calculation of the farmland water balance and the evaluation of the water resources.In order to study the dynamic variation and the influencing factors of cotton evapotranspiration in the arid region,this paper applies LCpro＋ photosynthesis system to measuring evapotranspiration of the cotton field with mulched drip irrigation in the Paotai Soil Improvement Test Station in Xinjiang Production and Construction Corps.The results show that the diurnal change of the cotton leaf transpiration rate and the soil evaporation rate of the no mulch zone fit to the single peak curve,namely high at noon while low at morning and night;the daily transpiration is 2.20 mm and daily soil evaporation of the no mulch zone is 0.16 mm,the daily evapotranspiration of single whole mulch is 2.21 mm,indicating that transpiration is the main way to consume the soil water at the flowering and boll opening stage;soil temperature and soil moisture show the fluctuating characteristic under the influence of the irrigation and meteorological conditions;the change of the leaf transpiration,soil temperature and soil evaporation obey the sinusoid curves,the soil temperature shows a more significant relationship with soil evaporation than transpiration;there is a good consistency between the soil moisture and the soil evaporation.