Selection for drought-prone rainfed lowland rice: can we use leaf rolling?
1998
Sigari, T.A. | Wade, L.J. (International Rice Research Inst., P.O. Box 933, 1099 Manila (Philippines))
Drought is usually considered the most severe limitation to productivity of rice in the rainfed lowlands. While plant breeders have successfully manipulated crop phenology for drought escape, progress has been slow in selecting lines with more complex traits conferring drought avoidance (better roots) or drought tolerance (osmotic adjustment). Absence of leaf rolling under drought has been used as an index of reduced drought sensitivity. However, this trait is highly modified by growth stage, plant size, and rate of stress onset. Data from four cultivars grown in different environments [Tarlac and IRRI (Philippines), Raipur, Bilaspur (India), Rajshahi (Bangladesh)] were analyzed to determine whether leaf rolling scores (LRS) may be adjusted for these other factors to make it a suitable selection index for drought sensitivity. LRS was correlated with total dry weight and leaf area, indicating that more vigorous plants attained higher LRS, not necessarily because of their sensitivity but because of their greater initial demand for water. The relationship between yield under stress and yield potential, flowering time, plant height, and LRS was examined. A procedure of using LRS as an indicator of drought sensitivity is discussed
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