Effect of potassium and zinc on growth and yield of cowpea [Vigna unguiculata (L.) Walp.]

A field experiment was conducted during kharif 2008 at Instructional Farm, Junagadh Agricultural University, Junagadh (Gujarat) on clayey soil to study the effect of potassium and zinc on growth and yield of cowpea. Twelve treatments comprising all possible combinations of four levels of potassium viz., control, 20, 40 and 60 kg/ha and three levels of zinc viz., control, 20 and 40 kg/ha were tried in factorial randomized block design with four replications. The growth and yield attributes as well as grain (1587 kg/ha) and stover (2047 kg/ha) yields were significantly increased by application of 60 kg K2O/ha over 40 kg K2O/ha, 20 kg K2O/ha and no potassium application. Application of zinc (ZnSO4) to the cowpea at 40 kg zinc/ha recorded remarkably higher plant height, yield attributes, grain (1553 kg/ha) and stover (2010 kg/ha) yields as compared to lower levels of zinc treatments. The higher net realization of Rs. 21725/ha with BCR (3.43) and Rs. 20545/ha with 3.18 BCR accrued under the application of 60 kg K2O/ha and 40 kg zinc/ha, respectively. Application of 60 kg K2O/ha along with 40 kg zinc/ha recorded the highest net realization of Rs. 24344/ha with BCR 3.54.