Organically-grown upland rice (Oryza Sativa L.) evaluation for drought adaptation

Upland Rice is mostly grown in extremely diverse ecosystems with highly degraded, infertile and acidic soils. Upland rice ecosystem is threatened by continued climatic changes such as erratic rainfall and high temperature resulting to drought condition. Among these climatic changes, drought is the major abiotic stress affecting upland rice production. Upland rice has shallow root systems, thus it is more susceptible to drought than other crops. Evaluation of traditional (Dinorado, Speaker, Cabuyok) and improved (UPL Ri5, UPL Ri7, IR-55 419) upland rice varieties organically grown in the field (dry season) and under rain shelter condition were conducted to characterize promising drought tolerant germ plasms for breeding and development of high yielding drought tolerant varieties. The improved upland rice variety IR 55419 produced comparably higher grain yield with traditional upland variety Speaker outperforming the improved UPL Ri-5 and two other local varieties, Dinorado and Cabuyok, respectively. The yield of improved upland rice variety IR 55419 and traditional variety Speaker were consistently higher even when subjected to drought induction. The amount of accumulated nitrogen decreases as the duration of drought induction increases. Traditional upland variety Speaker produced significantly higher dry matter at harvest followed by Cabuyok, Dinorado and IR 55429 while UPL Ri-5 produced the least. Harvest index was significantly highest in IR 55419 while lowest in Cabuyok. The higher grain yield in IR 55419 might be attributed by its higher harvest index. However, the higher grain yield in traditional upland rice variety Speaker might be attributed to consistently higher dry matter production before and after heading. The higher capacity in dry matter accumulation before and after heading in Speaker indicate it's potential characteristics as a vital source of genetic material in improving upland rice variety.