Abstract:
The vulnerability of most rice (Oryza sativa L.) crops to climate change and El Niño has severe implications on the agricultural industry. This has prompted the development of drought-tolerant varieties such as NSIC Rc288 (Sahod Ulan 10). The only previous work on Sahod Ulan10 discussed the effect of varying soil moisture levels on the vegetative growth of the variety. This study is the first detailed evaluation on the effect of timing and duration of water stress on the vegetative growth of Sahod Ulan 10. To study the effect of timing of water stress, Sahod Ulan 10 plants were exposed to water stress by withholding irrigation during the 2nd, 3rd, 4th and 5th week of vegetative phase, compared with continuous flooding. To study the effect of duration of water stress, the rice variety was exposed to water stress by withholding irrigation, starting on the second week of the vegetative phase, for 1, 2, 3 and 4 weeks, compared with continuous flooding. The mean scores for the number of leaves, leaf area, root and shoot lengths, and root-to-shoot dry weight ratio were compared among the treatments. The critical period in which Sahod Ulan 10 was most susceptible to water stress was during the 2nd to 3rd week of vegetative phase, with significant reduction in almost all vegetative growth parameters (except for dry weight ratio). There were no significant differences in the mean scores of the growth parameters between the treatments exposed to 1, 2, 3 and 4 weeks of water stress. The results of the treatment are presented such that they can be used to aid the design of irrigation schemes in drought-prone agricultural areas.
