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Genotypic Response in Rice During the Vegetative Phase under Water Stress and Non-stress Conditions

Efisue, Andrew A., Derera, John
Journal of crop improvement 2012 v.26 no.6 pp. 816-834
Oryza glaberrima, Oryza sativa, breeding, crop production, drought tolerance, environmental factors, genetic stability, genotype, genotype-environment interaction, irrigation rates, rice, sowing, sprinkler irrigation, stress tolerance, vegetative growth, water stress, Mali
Drought stress during the vegetative stage can cause irreversible damage to rice (Oryza sativa L.) plants, resulting in inadequate grain production. Morpho-physiological traits have been used as indirect measures of drought-stress tolerance in rice, but these traits are genotype and environment dependent. This study was therefore conducted to determine which morpho-physiological traits were associated with drought stress tolerance and to examine genotypic stability under different environmental conditions as potential genotype donors for drought tolerance breeding in rice. Sixteen genotypes, including seven Oryza glaberrima Steud, six interspecific (O. sativa x O. glaberrima) inbred genotypes, two improved O. sativa L. subspecies japonica genotypes, and a variety OS6 (drought-tolerant check) were evaluated for drought tolerance at the vegetative stage. Trials were conducted during the dry seasons of 2004 and 2005 at Samanko Research Station in Mali. A fully irrigated trial was included as a control in 2005. After sowing, overhead sprinkler irrigation was applied for 35 days, three times weekly. To induce stress, irrigation was withdrawn in the stressed experiments for 21 and 43 days in 2004 and 2005, respectively. Genotypes reacted differently to drought stress for the characters examined. Most of the genotypes examined under drought stress exhibited drought tolerance and avoidance mechanisms for most of the morpho-physiological characters under study. The GGE biplot revealed RAM163, WAB365-B-1-H1-HB, and WAB375-B-9-H3-2 to be stable genotypes under drought stress, which could be recommended for use as donor lines for the drought-stress improvement program.