Varietal response of cassava (Manihot esculenta Crantz) to water shortage at early vegetative stage
2002
Bergantin, R.V. (Leyte State Univ., Baybay, Leyte 6521 (Philippines). Philippine Root Crop Research and Training Center)
The performance of 28 cassava varieties under deficient soil moisture condition was studied during their establishment phase. The plants were grown in plastic pots (24.5 cm wide; 26.5 cm high) filled with sandy loam soil and kept under a rain shelter to regulate the moisture content of soil in the pots. The objective of this study was to determine the vegetative traits that may have something to do with drought resistance. Cassava exhibits genotypic variation in terms of its performance under limited water supply in the soil. With reference to the well-watered plants, the results generally showed that leafdrooping, leaf senescence, leaf fall and reduction in plant height, number of fully developed leaves, leaf and total plant dry weights were associated with water deficit; their magnitude being variable depending on the variety and time after the imposition of drought. The predawn and midday leaf water potentials, and midday transpiration rate of droughted plants, irrespective of variety, were suppressed. A highly marked increase in stomatal resistance was generally observed in response to drought. Traits such as high stomatal resistance, high leaf water potentials, high water use efficiency, high biomass, low transpiration rate, and low leaf fall were customarily manifested by the varieties that were observed to perform better under deficient soil moisture than the other varieties. On the other, hand, the opposite of these traits were commonly noted in the varieties that responded poorly to water shortage
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