Traditional Upland Rice (Oryza sativa L.) for Drought Adaptation in Marginal Uplands

Marginal upland rice ecosystem is threatened by persistent climatic changes such as drought. Upland rice has shallow root systems. Thus, it is more susceptible to drought resulting in lowering yield. The existing traditional (Dinorado, Speaker, and Cabuyoc) and improved (UPL Ri-5 and IR 55419) upland rice varieties were evaluated and characterized at Misamis Oriental State College of Agriculture and Technology research station (dry season) in 2010. A similar study was conducted in 2011 inside the rain shelter at the nursery area of the Department of Agriculture, Baungon, Bukidnon, Philippines. In 2012, one traditional upland rice (Speaker) variety and one improved (IR 55419) upland rice variety were physiologically characterized. The traditional upland rice 'Speaker' produced comparably higher grain yield with the improved upland rice variety IR 55419 outperforming the improved check variety UPL Ri-5 and two other traditional upland rice varieties, 'Dinorado' and 'Cabuyoc', respectively. The yields of 'Speaker' and improved variety IR 55419 were consistently higher even subjected to drought induction. 'Speaker' maintained a higher dry matter accumulation before and after heading, and shoots and roots dry weight throughout the growth period. Moreover, 'Speaker' maintained higher relative chlorophyll content and relative growth rate (RGR) before and after heading. The higher RGR in 'Speaker' was attributed to the higher net assimilation rate (NAR) and larger leaf area before and after heading than in IR 55419. The maintenance of higher relative chlorophyll value and higher NAR in 'Speaker' suggest its potential characteristics in improving marginal upland rice variety.

Keywords: agriculture, assimilation, chlorophyll, varieties, yield