Soil moisture variable patterns and irrigation in cotton field of Yudong Plain

Field studies on the soil moisture status and irrigation were conducted in the cotton field of Yudong plain, in order to try to find out the yield response to soil moisture status during cotton development stages (CDS).The results showed that there were three low folds of soil moisture during CDS, which appeared respectively at the anaphase of budding and flowering-boll forming stages (FBFS), and metaphase of ball beginning open stage (BBOS), those were 21～27 d, 69～75 d and 102～108 d after transplanting. The soil water reserves (SWR) came to higher level gradually from budding stage (BS) to FBFS, but at the betimes proper irrigation during FBFS and lower water consumption at ball opening peak stage (BOPS) may increase the yield and water use efficiency (WUE). From the regression correlation analysis between soil water consumption of BS, FBFS, BBOS, BOPS and yield in 2000～2002, the gained coefficients which influenced the yield were 0.24, 1.48, -0.12 and -0.33, respectively. The result show that the effect sequence of irrigation in cotton field on CDS is FBFS＞BS＞BBOS＞BOPS.