Abstract

A series of experiments were conducted in farmers’ fields in different locations of Jharkhand with medium to high fertility status of available potassium (K) to study the response of selected vegetable crops viz. French bean (Phaseolus vulgaris), brinjal (Solanum melongena L .), cucumber (Cucumis sativus), bitter gourd (Momordica charantia), potato (Solanum tuberosum), bottle gourd (Lagenaria siceraria), ridge gourd (Luffa acutangula), green chili pepper (Capsicum annuum L.), and sweet pepper (Capsicun annuum var. glossum) to different K regimes. Five K treatments were tested: 1) K-free, farmers’ fertilization practice (FFP); 2) recommended dose (100%), basal application; or, 3) split into basal and a second application at bloom; 4) enhanced (150%), basal application; or 5) enhanced, split as above. Nitrogen (N) and phosphorus (P) were uniformly applied according to recommendations. All nine crops displayed a significant increase (average - 31%) in yields in response to K application at recommended dose, as compared to FFP. The enhanced dose gave rise to a smaller yield increase, only 22% above the recommended dose, on average, which was also characterized by large variation between crops. Split K applications improved the yield of most crops, but to a much lesser extent. The differences among crop species regarding the linkage between crop K requirements in terms of life span and phenological phases, cropping patterns, and K and carbohydrate contents in harvested organs, are discussed. In conclusion, K application is essential, if exploiting the potential of vegetable crops and seeking to enhance the net return to farmers. For most crop species tested, recommended K dose should be revisited and upgraded. The positive response to split K dose may indicate that it is beneficial to distribute K application along the cropping season.