CHAPTER 6.RICE

Authors: HORIE, T - KYOTO UNIVERSITY, JAPAN; Baker, Jeffrey; NAKAGAWA, H - KYOTO UNIVERSITY, JAPAN; MATSUI, M - KYOTO UNIVERSITY, JAPAN

Submitted to: Climate Change and Global Crop Productivity
Publication Type: Book / Chapter
Publication Acceptance Date: 3/15/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Global climate change involves rising levels of carbon dioxide (CO2) in the earth's atmosphere. This rise in carbon dioxide concentration is also expected to cause an increase in air temperatures. Rice is a major source of food for a large portion of the world's human population. Rice growth and yield are known to be affected by both atmospheric carbon dioxide concentration and air temperature. In this chapter, we review recent climate change research on rice. Effects of doubling current CO2 can be summarized as follows: 1) Photosynthesis was increased by 30-40% over a wide range of air temperatures; 2) Number of days to harvest was shortened by 5-10%; 3) Plant weight was enhanced by an average of 24%; 4) At air temperatures above the optimum, rice grain yield declined sharply due to a shortening of crop growth duration and increased spikelet sterility; 5) CO2 enrichment decreased the amount of water required to produce rice but with increasing air temperatures more water was required and; 6) Comparisons of results from potted plant experiments vs. experiments conducted in the field indicate a need for caution when extrapolating the results of potted plant experiments to real world scenarios of potential future global climate change. We conclude that the combination of a doubling of current CO2 along with increased air temperature may result in increased grain yield for irrigated rice in northern and tropical Asia, while yields may be reduced for inland areas of subtropical Asia, especially during the warmer dry season.

Technical Abstract: Future global climate change will include increases in atmospheric carbon dioxide concentration ([CO2]) and air temperatures. Rice is a major food source for a large proportion of the Earth's population. It is critically important to predict the effects of these climate change variables on rice production. In this chapter, we review and summarize recent climate change research conducted on rice. Effects of doubling current ambient [CO2] can be summarized as follows: 1) Canopy net photosynthesis was increased by 30-40% over a wide range of air temperatures; 2) Number of days to heading was shortened by 5-10%; 3) Biomass accumulation was enhanced by an average of 24%, 4) At mean daily air temperatures above 26 degrees C, rice seed yield declined sharply for both ambient and enriched [CO2] treatments due to a shortening of growth duration and increased spikelet sterility; 5) [CO2] enrichment increased crop water use efficiency by 40-50% over ambient controls, but this effect was sharply reduced with increasing air temperatures and; 6) Comparisons of results from potted plant experiments vs. field experiments indicate a need for caution when extrapolating the results of potted plant experiments to real world scenarios of potential future global climate change. Simulation studies with available rice models indicated that the combination of a doubling of current ambient [CO2] along with increased air temperature may result in increased yield for irrigated rice in northern and tropical Asia, while yields may be reduced for inland areas of subtropical Asia, especially during the dry season.