Effects of different drip irrigation programs on the boll number and shedding percentage and yield of cotton

This study investigated the effects of different drip irrigation programs on boll number, shedding percentage, and yield of cotton. The amount of water used was based on free surface evaporation from a screened class-A pan. Irrigation treatments consisted of two different irrigation intervals (I1:5 days; 12: 10 days), three plant-pan coefficients (K(cp)1: 0.75; K(cp)2: 0.90; K(cp)3: 1.05) and two different wetting factors (P1: 0.70 (constant) and P2: based on cover percentage of the crop). The first irrigation was carried out when the available water in the 120 cm of the soil profile was at the 40% level. The results revealed significant linear relationships between cotton yield-irrigation water and boll number-shedding percentage. On the other hand, the shedding was decreased by increasing the amount of applied irrigation and irrigation interval. Therefore, the yield increased by increasing the boll number. Furthermore, it was found that there was a significant (P < 0.01) inverse linear relationship between the shedding rate and boll number. (C) 2002 Elsevier Science B.V. All rights reserved.