Local climate affects growth, yield and grain quality of aromatic and non-aromatic rice in northwestern India

During the last two decades, night temperatures have increased at a much faster rate than day temperatures and global climate models predict further increase in both frequency and intensity. Such rapid increase during the crop growth stages, particularly during extremely sensitive reproductive and early grain-filling stages of rice (Oryza sativa L), leads to reduced biomass, grain yield and quality. Field experiments and lab analyses were carried out using three Basmati and two non-Basmati cultivars to study the effect of a wide range of diurnal temperatures and radiation. Night temperature had a significant negative effect on grain yield (P < 0.001) and quality (P < 0.01) beyond 22 degrees C. Reduced spikelet fertility followed by grain weight plant(-1) accounted for the decline in yield. Radiation however had a positive influence on yield and grain quality. A definite relationship between maximum day temperature and grain yield could not be established as the temperatures were generally <= the critical 35 degrees C during sensitive developmental stages. Environment 4 gave significantly highest yield, indicating a narrow window of optimum growing conditions for better yield and quality. Hence, increasing diurnal temperature tolerance in rice is a sustainable approach than altering well established cropping patterns, which will inevitably lead to yield penalties. (C) 2010 Elsevier B.V. All rights reserved.