Abstract:  

Using the daily meteorological data from 28 stations in Gansu Province,China from 1967 to 2017,the water required by wheat during its growing period was calculated with Penman-monteith formula.The effective precipitation in wheat’s whole growing period was calculated based on the method recommended by the USDA Soil Conservation Bureau.So we can get the water deficit of wheat during its life cycle.In addition,we analyzed the variation trend and spatial distribution characteristics of water requirement and water deficit of spring wheat and winter wheat as well as the affect factors of water requirement.The results showed that the annual average water requirement of spring wheat and winter wheat was 517.03 mm and 436.70 mm respectively and the annual average water deficit of spring wheat and winter wheat was 468.24 mm and 301.54 mm respectively in Gansu Province from 1967 to 2017.In the past 51 years,there was no significant change in the water requirement and water deficit in the spring wheat planting area,while there was a significant increase in the water requirement and water deficit in the winter wheat planting area.Spatially,the water requirement and water deficit in spring wheat planting area were decreased gradually from northwest to southeast,while the water requirement and water deficit in winter wheat planting area were decreased gradually from west to east.The sunshine hours and daily average temperature during the growth period of wheat in Gansu province are the main factors affecting the water requirement of wheat.

Key words: Penman-Monteith formula, water requirement, water deficit, effective precipitation, Gansu Province