SOME PHYSIOLOGICAL CHARACTER RESPONSES OF RICE UNDER DROUGHT CONDITIONS IN A PADDY SYSTEM

The most serious impact of climate change is the El Nino phenomenon that creates increased drought in paddy systems. Drought is the most important limiting factor for the sustainability of rice production. This research aimed to identify the physiological character of drought tolerant rice varieties in a paddy system under greenhouse conditions. The experimental design used was split plot design with three replications, with drought stress as the main plot and variety as sub-plot. The main plots consisted of a control (normal irrigation) and drought stress (drought imposed three weeks after transplant up to harvest). The sub-plots consisted of eight rice varieties: IR 64, Ciherang, IPB 3S, Way Apo Buru, Jatiluhur, Menthik Wangi, Silugonggo, and Rokan. Results showed that drought stress led to a decrease in grain yield per hill, chlorophyll a content and chlorophyll a/b ratio, and an increment of proline and total sugar accumulation. Tolerant varieties (Ciherang, Way Apo Buru and Jatiluhur) accumulated proline over a longer time and increased accumulation of total sugar at the stage of pre anthesis. Jatiluhur varieties showed less reduction in grain yield under drought stress (40.7%) than other varieties. Less reduction in grain yield under drought stress, accumulation of proline in a longer time, and an increased total sugar accumulation at anthesis phase during drought were physiological characters that played an important role in tolerance to drought stress in paddy systems. Key words: chlorophyll, proline, starch, total sugar

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