Physiological and lipid changes in some upland rice (Oryza sativa L.) cultivars grown under drought stress
1988
Taher, A.
Rice varieties showed varying responses to drought stress. Upland varieties (M1-48 Kinandang Patong, and Salumpikit) were less affected by the stress compared to the lowland varieties (IR8 and IR20). Several plant characters, total lipid, lenoleic acid, linolenic acid, epicuticular wax, proline content, relative water content, leaf water potential, and leaf area were found closely associated with drought resistance. The seeds of drought resistant varieties were characterized by higher lipid and linolenic acid content and also higher critical osmotic potential when hardened. The hardened plants had higher epicuticular wax content, greater flag leaf area, more spikelets per panicle and higher grain yield when subjected to drought stress. Leaf area seems to be a limiting factor under drought stress. The effect of drought stress was severe in varieties with higher leaf area. Drought tolerant varieties had higher relative water content, leaf water potential, total lipid, linoleic, and linolenic acid content than the drought susceptible variety. The drought tolerant varieties increased their proline and epicuticular wax content when subjected to drought stress. The reproductive stage of both upland and lowland rice was more sensitive to drought stress than the vegetative stage. This was primarily due to the lower capacity of the plants to synthesize epicuticular wax and proline at the later stage.
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