Impact of Climate Variability on Phenology of Rice

Rice (Oryza sativa L.) is an important staple food for nearly half of the world population. It is extremely variable in phenology which depends strongly on cultivars and prevailing environmental conditions. During the last three decades, rice production is showing a declining trend, and it is expected to continue because of anthropogenic practices involving emission of greenhouse gases (GHGs) that contribute to the global climate change. The weather and climate variability directly influence the phenological development of rice such as canopy radiation capture, biomass production, seed germination, crop duration and maturation, and grain yield that lead to food insecurity. The warnings in weather episodes modify rice cultivars to grow in vulnerable situations and even changes in agronomic management practices. In rice, plant developmental responses to elevated temperature vary significantly at all vegetative and reproductive stages. Due to high temperature, vapor pressure deficit increased and enhances evaporation from the anthers which results in anther dehiscence, reduced pollination, pollen germination, and pollen tube growth. Increase in CO2 concentration in the atmosphere increases the grain yield in rice to an extent, but further CO2 elevation shows negative result. In addition, high temperature contradicts the positive effects of CO2 fertilization on plant. However, rice is relatively more tolerant to weather variability during germination and active tillering and toward maturity but sensitive during early vegetative and reproductive stages. Reproductive processes in rice especially flowering stage show greater sensitivity to drought than do vegetative processes. Hence, appropriate mitigation strategies need to be adopted on sustainable basis to combat the menaces in crop cultivation and to feed the population explosion.