Effect of Extended Water Stress on Growth, Tiller Mortality and Nutrient Recovery Under System of Rice Intensification

Abstract

System of rice intensification was initially introduced to increase rice productivity in India, but is recently popularized as promising water saving practice. Sustaining rice productivity with minimal use of water is the need of the day. In this background, an experiment was designed to assess the effect of variable degrees of water stress namely no-stress, mild-stress and prolonged-stress imposed throughout the crop growth by scheduling irrigation at 1, 3 and 5 days, respectively after disappearance of ponded water under system of rice intensification with two different planting geometry and two contrasting varieties. Results clearly demonstrated that mild and prolonged stress during late vegetative stage (45–75 days after transplanting) greatly (P ≤ 0.05) enhanced (30.3–41.5 %) crop growth rate while, any level of stress during reproductive phase reduced (8.8–10.8 %) the rate of crop growth. Despite of higher tiller production under stress condition, large number of tillers failed to convert in ear-bearing tillers indicating higher tiller mortality under stress environment. Meanwhile, tiller density was not confirmed as a yield determinant while, the rice yield had higher correlation with grain weight panicle⁻¹ (r = 0.743*), filled grain percentage (r = 0.806*), test weight (r = 0.683*) and nutrient uptake. With increase in stress intensity, apparent recovery of nutrients significantly (P ≤ 0.05) reduced, and the decline rate was in the order of potassium > phosphorus > nitrogen. Rice crop imposed mild-stress maintained at par yield (P > 0.05) with no stress, however prolonged-stress resulted in significant yield loss. Thus, mild-stress throughout the crop growth can reduce the water requirement and would be an effective water management strategy under water limited conditions.