EVEPOTRANSPIRATIONS AND ENERGY BALANCE ON THE RAINFED SPRING WHEAT FARM

By using observational data of lysimeter and so on, the evapotranspiration consumption water on the rainfed spring wheat farm in semi-arid regions was analysed. It was obtained that: (1) under normal precipitation year input output water on rainfed farm is essentially balance, and evaporation in fallow farm duration amounts 70% to precipitation of that duration. (2) duration in which rainfed wheat evapotranspiration reachs 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, averaged daily evapotranspiration of raindfed wheat is small. (3) there is good linear reladons 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 the consumption 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 the bare soil between stems and stems, heat consumption from surface soil to deep soil also has a definite percentage.