Evaluation of heat and cold tolerance of rice varieties at booting and flowering stages
2013
Yu, Y. | Tenorio, F.A. | Redona, E.D. | Ye, C.
As a result of climate change, extreme temperature events occurred more frequently and had significant negative effect on rice production. Heat stress due to increased average temperature is a serious threat for food security worldwide. And low temperatures also cause major problems for many rice growing countries, even in tropical countries such as in the northern mountainous regions of the Philippines and Thailand. Booting and flowering stages are the most susceptible stages to both high (35 deg C) and low (20 deg C) temperature in rice, because the reproductive stage is critical for spikelet fertility and ultimately yield of rice. High and low temperature during microsporogenesis causes degeneration of microspores and hypertrophy of tapetal cells in the anther. The number of fertile and shredded pollen grains is highly correlated with the final spikelet fertility. Therefore, it is thought that the amount of pollen is an important factor in the mechanism of tolerance. In addition, anther dehiscence is more significant factor which is closely related to high temperature stress. Delayed anther dehiscence causes poor pollen shed and decreased number of pollen grains intercepted by the stigma. To identify key factors affecting spikelet fertility under heat and cold conditions, five Indica (IR72, N22, IR64, NSIC222, NSIC238), three Indica X Japonica (Giza 178, Dasan, Milyang 23) and four Japonica (Todorokiwase, Chenoncheong, KeunSeom, TR22183) varieties are exposed to 38/24 deg C (heat stress) and 21/15 deg C (cold stress) for 14 days at the booting and flowering stages, and the anther and pollen related traits are measured. The key traits affected by extreme temperature and the possibility of developing wide-adapted rice variety for different temperature conditions are presented.
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