EFFECT OF SUBSTRATE MOISTURE AND POTASSIUM ON WATER RELATIONS AND C, N AND K DISTRIBUTION IN VIGNA-RADIATA

The Vigna radiata L. plants were grown in greenhouse at moisture conte nt of sand (SMC) of 12.0 +/- 0.5 %. At flower bud initiation stage, ie . 45 - 50 d after sowing, the SMC was decreased to 3.5 +/- 0.5 %, and the effects of applied potassium (0, 2.56 and 3.84 mmol dm(-3)) were s tudied, During water stress, K-fed plants maintained higher leaf water potential and relative water content (RWC) of leaves and nodules and lower osmotic potential as compared to untreated plants. The proline c ontent was higher in nodules than in leaves showing their difference i n degree of stress. A partial recovery was found after re-irrigation. When subjected to drought, carbon was accumulated in the leaves and de clined in nodules and roots. K-fed plants showed higher C and N conten t in stem, roots and nodules than untreated plants. The content of K s ignificantly increased in stem and nodules in K-fed plants, irrespecti ve of SMC. Dry masses of different plant parts were also increased in K-fed plants.