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 include application of N fertilizer and plant growth regulators (PGRs). Since N-fixing bacteria produce plant growth substances (PGRs), the effect of foliar application of an active strain of Klebsiella sp. (KUPOS) on IR-50 rice was examined using three foliar sprays applied at 10-day intervals. Irrigation once every 3 days was essential for plant growth. Application of KUPOS and 40 kg N ha improved grain yield of acutely water stressed plants from 330 kg ha to more than 1300 kg ha along with an improvement in several growth variables and yield determinants. Indole acetic acid, kinetin and GA, in a mixture of 10 M of each, were less effective than KUPOS in alleviating stress effects. The adverse effects of water stress on respiration and photosynthesis as indicated by CO exchange were also alleviated by these treatments. While uptake of K, Mg, Ca, Fe and Mo was increased, Na content decreased, accompanied by an increase in proline content. The order of effectiveness of the treatments was 40 kg N ha >KUPOS>PGRs. [ABSTRACT FROM AUTHOR]