旱作春小麦农田蒸散与能量平衡

EVEPOTRANSPIRATIONS AND ENERGY BALANCE ON THE RAINFED SPRING WHEAT FARM

利用蒸渗计等仪器设备的观测资料，分析了旱作春小麦农田的蒸散耗水状况。得在降水基本正常的年份，农田水分收支基本平衡，农田休闲期蒸发耗水约占期间降水的７０％。旱作小麦的实际蒸散耗水峰值期与小麦生理需水峰值期并不一定吻合。与有灌溉条件的春小麦相比，平均日蒸散量偏小。各生育期的平均叶面积系数与平均日蒸散强度存在较好的线性关系。小麦主要生育期的地表能量平衡分析表明：潜热耗能占主导地位，乳熟－黄熟生育时段以感热、潜热耗能为主的出现几率各为５０％。由于旱作春小麦株冠不能完全覆盖棵间裸地，地表向下的热量传输耗能也占有一定的比重。

By using observational data of lysimeter and so on, the evapotranspiration consumption water on the rain fed spring wheat farm in semi-arid regions was analysed. Itwas obtained that: (1) under normal precipitation year input output water on rainfedfarm is essentially balance, and evaporation in fallow farm duration amounts 70% toprecipitation of that duration. (2) duration in which rain fed wheat evapotranspirationreachs its peak value is not agreement with duration in which the physiological consumption water of wheat reachs its peak value. Compared with irrigated spring wheat,aver aged daily evapotranspiration of raindfed wheat is small. (3) there is good linear relations between averaged leaf index and averaged daily evapotranspiration intensity in respective grow duration. (4) in main grow duration of rainfed wheat the consumption energy of latent heat is dominant, but in sucking ripeness￣sallow ripeness duration theconsumption energy of latent or sensible heat which play a leading role is a half percentage respectivelly. (5) because conopies of rainfed spring wheat is not able to cover thebare soil between stems and stems. heat consumption from surface soil to deep soil alsohas a definite percentage.