AMELIORATION OF WATER-STRESS EFFECTS ON WETLAND RICE BY UREA-N, PLANT-GROWTH REGULATORS, AND FOLIAR SPRAY OF A DIAZOTROPHIC BACTERIUM KLEBSIELLA SP

Some of the measures suggested for amelioration of drought effects inc lude application of N fertilizer and plant growth regulators (PGRs). S ince N-2-fixing bacteria produce plant growth substances (PGRs), the e ffect of foliar application of an active strain of Klebsiella sp. (KUP OS) on IR-50 rice was examined using three foliar sprays applied at 10 -day intervals. Irrigation once every 3 days was essential for plant g rowth. Application of KUPOS and 40 kg N ha(-1) improved grain yield of acutely water stressed plants from 330 kg ha(-1) to more than 1300 kg ha(-1) with an improvement in several growth variables and yield dete rminants. Indole acid, kinetin and GA(3), in a mixture of 10(-4) M of each, were less effective than KUPOS in alleviating stress effects. Th e adverse effects of water stress on respiration and photosynthesis as indicated by CO2 exchange were also alleviated by these treatments. W hile uptake of K, Mg, Ca, Fe and Mo was increased, Na content decrease d, accompanied by an increase in proline content. The order of effecti veness of the treatments was (40) kg N ha(-1) >KUPOS>PGRs.