Improved Management Alleviating Impact of Water Stress on Yield Decline of Tropical Aerobic Rice

Abstract

Yield decline is the major concern in tropical aerobic rice (Oryza sativa L.). Both biotic and abiotic factors were responsible for this phenomenon. No analytical information on actual causes was reported taking into account of responses of root to water stress conditions. In a field experiment at the Central Rice Research Institute, India during 2009 and 2010, five rice genotypes were grown under two soil water conditions, aerobic and semi‐aerobic condition, for better understanding of yield penalty vis‐à‐vis yield stability. Results showed aerobic condition significantly inhibited structural development of root and caused significant variation in biochemical root traits accounting for higher concentration of hydrogen peroxide (24.6%) and proline (20%), and lower concentration of total soluble protein (20%) that resulted in 17% yield decline than semi‐aerobic condition. Applying supplementary irrigation at semi‐aerobic condition achieved 21% more grain yield compared with aerobic condition due to 21%, 8.3, and 10.4% more root biomass, root volume, and root/shoot ratio, respectively. Interaction of genotypes with soil water conditions revealed that at aerobic condition, better performance could be expected in ‘Apo’(4.0 t ha−1) and ‘IR 74371‐3‐1‐1’ (3.80 t ha−1) with less yield decline (7.0–9.5%); supplementary irrigation enhanced their grain yield (4.3–4.4 t ha−1) at semi‐aerobic condition. Therefore, detrimental impact of physical and biochemical root traits’ changes on yield decline in aerobic rice could be alleviated with supplementary irrigation at critical growth stages under semi‐aerobic condition without compromising with water productivity.