ASSESSING THE EFFECTS OF APPLIED POTASSIUM ON SELECTED VIGNA RADIATA L. GENOTYPES UNDER WATER DEFICIT

Vigna radiata L. (Mungbean) is one of the most important pulse crops for protein supplement in a subtropical zone of the world, as it is the best alternative to meet the food needs of the large population of developing countries due to its nutritional superiority. The performance of two mungbean genotypes SML-668 and MH-318 to potassium fertilization 0.00, 1.54, 2.31and 3.08 mmol dm-3 in addition to the existing level of 1.32 mmol dm-3 in the soil medium was investigated under water deficit. Water stress (Soil Moisture Contents 4.5 ± 0.5 %) was created by withholding irrigation at different growth stage. Water stress at flowering stage caused highest reduction in leaf area (36.4%), photosynthetic rate (71.4%), total chlorophyll contents (45.2%) and dry weights of various plant parts. Dry weights of various plant parts, leaf area, photosynthetic rate, stomatal conductance and chlorophyll contents at all sampling stages were enhanced by potassium application under control as well as stress conditions. Cultivar SML-668 proved more tolerant to water stress as compared to MH-318. This study provides direct evidence of the beneficial physiological functions of potassium fertilization in mitigating the adverse effects of water stress.