Abstract: Based on observed daily precipitation data during whole growth period of spring potato（from sowing to harvest）from 2006 to 2011 and average yield data of Weiyu 3 at 4 test spots with different altitude in Liuzhi,Zhongshan,Shuicheng and Pan county in western Guizhou,the precipitation change and its effect on spring potato yield was analyzed by using precipitation yield integral regression method.The results showed that the spatial and temporal distribution of precipitation in western Guizhou was inhomogeneous,but the precipitation increased with the altitude rising.The main reason to unstable yield of spring potato was uneven distribution of precipitation in different growth stages and less precipitation in whole growth period（less than 600mm）.The optimal irrigation time during whole spring potato growth period was different in different regions.Irrigation was needed at emergence stage,branching stage and squaring stage in eastern Guizhou,irrigation was needed at seeding time,emergence stage,squaring stage and flowering stage in northern Guizhou.Supplementary irrigation was needed at flowering stage in northern Guizhou,and supplementary irrigation was needed at full blooming stage in center of Guizhou.The research result was helpful to determine the optional irrigation time of spring potato,optimize the production patterns and increase spring potato yield.

Key words: Weiyu 3, Relationship between precipitation and yield, Supplementary irrigation, Western Guizhou