Impact of climate change on production and nutritional qualitites of rice

Abstract

Rice (Oryza sativa L.) is the major staple food for more than half of the world's population (FAO, 2013), accounting for approximately 30 percent of the total dietary intake, globally and in South Asia (Lobell et al., 2008). Rice production in the tropics is vulnerable to climatic factors, which affect the crop in various ways during different stages of its growth (Yoshida, 1973). The rising temperatures and carbon dioxide and uncertainties in rainfall associated with climate change may have serious direct and indirect consequences on rice production and nutritional aspects. Nowadays, most of the rice is currently cultivated in regions where temperatures are already above the optimum range for growth of rice. Therefore, any further rise in temperature during crop growth period may adversely affect the growth and yield of rice. The present experiment was aimed to study the impact of climate change on production and nutritional qualities of rice. Rice variety, Jyothi was raised at Regional Agricultural Research Station, Pattambi by adopting completely randomized design with two factors. The experiment was laid out with five dates of planting (June 1st, June 30th, October 1st, October 30th and January 1st) as first factor and the two growing conditions (open condition and climate controlled greenhouse) as second factor. Three replications were given for the experiment with ten pots under each replication. The future climate was estimated by climate change projections generated using ECHAM and GFDL-CM3 models for 2030, 2050 and 2080 based on scenarios RCP, 4.5 and 8.5. Duration taken for each phenophases found to vary for both the growing conditions in Jyothi. Plants grown under open condition took more days to attain different phenological stages. Phenophase duration was negatively influenced by maximum temperature. Plants grown under climate controlled greenhouse recorded significantly higher plant height and leaf area index when compared to plants grown under open

condition. Yield recorded was maximum under open conditions compared to climate controlled greenhouse. October 30th planting showed significantly higher yield in both conditions. Similarly straw yield was significantly influenced by dates of planting and growing conditions. October 30st planting had higher straw yield compared to other dates of planting and plants grown under climate controlled green house gave higher straw yield compared to open condition. It was observed that increased minimum temperature had significant negative effect on grain and straw yield. Effect of dates of planting on dry matter accumulation at harvest was found to be significant. Maximum dry matter accumulation was recorded during October 30th planting and dry matter accumulations recorded during all other plantings were on par with each other. Maximum temperature and soil temperature showed negative influence on thousand grain weight under both the growing conditions. Cooking and nutritional quality parameters were found to be higher in plants grown under open condition, compared to that under climate controlled greenhouse. Milling percentage and head rice recovery found to be decreased with increase in maximum temperature. Higher maximum temperature had significant negative effect on strarch, amylose, protein, fat and mineral content in grains. Briefly, grain quality deteriorated under high temperature conditions. Performance of the CERES-RICE model was tested and evaluated using the calibrated genetic coefficients for the variety Jyothi. Observed grain yield, panicle initiation day, days to anthesis and physiological maturity days showed good agreement with simulated value. The simulation analysis as per the projected climate change scenarios for the period of 2030, 2050 and 2080 showed that among different date of planting, performance of rice variety Jyothi is better in October 1st planting. In RCP 4.5, which is the most likely scenario of India, the yield reduction will be 13.8, 16.9 and 24.5

percent respectively during 2030, 2050 and 2080. Whereas under RCP 8.5 scenario, yield reduction observed was 15.3, 27.4 and 39.7 percent respectively during 2030, 2050 and 2080. The yield reduction in almost all the planting dates under RCP 4.5 and RCP 8.5 scenarios was due to increased minimum and maximum temperature and increased rainfall during anthesis. In short, field experiment and impact studies using CERES-rice model give the similar results that increased temperature has a significant negative effect on yield and nutritional aspects of rice. Similarly increased rainfall at anthesis stage has adverse effects on crop performance.