Mild to prolonged stress increased rice tillering and source-to-sink nutrient translocation under SRI management

Abstract

System of rice intensification (SRI) is a water-saving agro-technique being popularized in Southern Asia including India. A particular key practice in SRI, reduced water application (no continuous flooding), needs to be more farmer-friendly for its mass adoption under traditional and non-traditional cultivation. A field experiment was conducted maintaining different water regimes throughout the crop season (vegetative as well as reproductive stages) by scheduling irrigation applications at 1, 3, or 5 days after disappearance of ponded water (DADPW), using two different plant spacings and two different varieties. With an increase in the period of water stress, tiller production was increased significantly (P ≤ 0.05) and found to be maximum under prolonged stress, i.e., 5 days after disappearance of ponded water (5 DADPW). Increased tiller production did not result in yield increments, but yield-contributing parameters (panicle weight, grain weight per panicle, filled grain percentage, and test weight) were confirmed as critical determinants of yield. Plant nutrient (NPK) uptake was reduced under stress conditions, but the translocation of phosphorus and potassium from sources to sink was increased significantly in this study. Nutrient utilization efficiency was also enhanced under mild (3 DADPW) to prolonged (5 DADPW) water stress conditions. No significant reduction in yield was recorded under mild water stress, and this resulted in increased water productivity; however, significant yield loss was observed under prolonged water stress (5 DADPW).