Submitted to: Advances in Agronomy
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/15/2010
Publication Date: 5/16/2011
Citation: Krishnan, P., Ramakrishnan, B., Reddy, K.R., Reddy, V. 2011. High temperature effects on rice growth, yield, and grain quality. Advances in Agronomy. 111:87-205. Interpretive Summary: Rice is a globally important cereal crop and it is a primary source of food for more than 3 billion people living mostly in Asia and Africa. The world’s population is projected to be 10 billion by the year 2050, and most of the population growth is expected in Asia and Africa resulting in higher demand for rice. There are already challenges to achieve higher yields of rice including shortage of water, flooding, above optimum temperatures, and pest and disease problems. The predicted climate change includes rise in temperature which is extremely detrimental as most of the rice production presently is in the regions of the world where temperature is above optimum for rice production. In this paper, a comprehensive review on the impact of high temperature stress on rice under a range of ecological conditions is provided. The effects of high temperature stress on growth, development, yield and grain quality of rice are discussed. The adaptation and mitigation technologies, including the use of conventional and molecular breeding methods, and crop growth simulation models for dealing with high temperature stress, are also discussed. This information is useful for scientists, rice growers, and policy makers in the rice growing regions of the world.
Technical Abstract: Rice (Oryza sativa L.) is a globally important cereal plant, and as a primary source of food it accounts for 35-75% of the calorie intake of more than 3 billion humans. With the likely growth of world’s population towards 10 billion by 2050, the demand for rice will grow faster than for other crops. There are already many challenges to achieving higher productivity of rice. In the future, the new challenges will include climate change and its consequences. The expected climate change includes the rise in the global average surface air temperature. At the end of the 21st century, the increases in surface air temperature will probably be around 1.4-5.8 °C, relative to the temperatures of 1980-1999, and with an increase in variability around this mean. Most of the rice is currently cultivated in regions where temperatures are above the optimal for growth (28/22 °C). Any further increase in mean temperature or episodes of high temperatures during sensitive stages may reduce rice yields drastically. In tropical environments, high temperature is already one of the major environmental stresses limiting rice productivity, with relatively higher temperatures causing reductions in grain weight and quality. Developing high temperature stress tolerant rice cultivars has become a proposed alternative, but requires a thorough understanding of genetics, biochemical, and physiological processes for identifying and selecting traits, and enhancing tolerance mechanisms in rice cultivars. The effects of high temperature stress on the continuum of soil-rice plant-atmosphere for different ecologies (with or without submerged conditions) also need detailed investigations. Most agronomic interventions for the management of high temperature stress aim at early sowing of rice cultivars or selection of early maturing cultivars to avoid high temperatures during grain filling. But these measures may not be adequate as high temperature stress events are becoming more frequent and severe in the future climate. In this review, the effects of high temperature stress on rice growth, yield, and quality characters, including various morphological, physiological, and biochemical mechanisms along with the possible use of conventional and molecular breeding methods, and crop growth simulation models and techniques are discussed. The mitigation and adaptation strategies for dealing with high temperature stress in rice are highlighted. We conclude that there are considerable risks for rice production, stemming from high temperature stress but benefits from the mitigation or adaptation options through progress in rice research may sustain the production systems of rice in the future warmer world.