Abstract
Drought is regarded as one of the limiting factors in rice production nationally and globally. The present study was conducted to study morpho-physiological and biochemical responses of rice genotypes to drought stress, to identify potential traits for use as a selection criterion in breeding drought-tolerant rice at seedling stage and finally to identify rice genotype resistant to drought stress for use as parents in future breeding. The experimental design used was a split-plot design with three replications, with drought stress as the main plot and rice genotypes as the sub-plot. The main plots consisted of control (normal irrigation) and drought stress. The sub-plots consisted of twelve rice genotypes namely Apami (V1), Boewani (V2), Basmati 370 (V3), Cica- 4 (V4), Dular (V5), Jarom mas (V6), Kalarata (V7), Biris (V8), Haiboq (V9), Moroberekan (V10), MR 297 (V11) and Aerob 1 (V12). Results showed that drought stress led to a decrease in plant height, leaves size, root length, total dry weight, and number of leaves but an increment in proline content. The genotype Apami and Kalarata were found to accumulate higher proline content indicating potential resistant ability towards drought stress. Dular and Aerob1, along with tolerant control genotype, Moroberekan, on the other hand, recorded a lower SES score. Leave size, root length, and plant height could also be used as a selection criterion in breeding drought-tolerant rice due to high values of broad-sense heritability and genetic advance by percentage of mean (GAM). Nevertheless, further study on the genetics and physiological basis of tolerant ability at reproductive growth stages are necessary in order to assess grain yield potential of the potentially tolerant genotype reported in this study.
Highlights
Most rice cultivars are susceptible to drought due to its small root system, thin cuticular wax, and swift stomata closure
According to Hsiao (1982), leaf rolling was induced by the loss of turgor, and poor osmotic adjustment in rice and delayed leaf rolling is an indication of turgor maintenance and dehydration avoidance (Blum,1989)
The screening of 12 rice genotypes in this study revealed ample genetic diversity in concerning their response for all traits measured at the early stages of growth under drought stress
Summary
Most rice cultivars are susceptible to drought due to its small root system, thin cuticular wax, and swift stomata closure. Seed germination and early seedling growth are among the most critical stages for water stress (Ahmad et al, 2009). During the seedling growth stage, the effects of water deficit lead to inhibition of cell growth, expansion, and division (Jaleel et al, 2008). Drought is a major problem that limits the adoption of highyielding rice varieties in drought-prone rainfed rice environments where high sensitivity to even short periods of water deficit constitutes a risk that farmers cannot afford to take (Lafitte et al, 2007). This study was conducted to assess the sensitivity and tolerant ability of selected rice genotypes to drought stress at seedling stage with the ultimate aim to develop selection criteria for drought resistance and identify resistant genotypes for use as parents in future the breeding program
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