Physiological growth analysis and changes in relative chlorophyll content of traditional high-yielding upland rice

Upland rice (Oryza sativa L.) farming is considered an important initiative in attaining the goal of rice sufficiency and in alleviating upland farmers' income in the Philippines. However, upland rice farmers are still living below poverty line due to lower yield and income. Lower yield of upland rice can be augmented by using location specific and high-yielding traditional and improved upland rice varieties. The high-yielding traditional upland rice variety (Speaker) consistently produce higher grain yield and dry matter even subjected to drought induction. At any given time, upland rice is composed of leaves of physiologically different ages that influence dry matter production and yield. The physiological growth parameters and the changes in relative chlorophyll contents of high-yielding traditional upland rice variety (Speaker) were analyzed by comparing with the improved upland rice variety (IR 55419) with five replications. The superiority of Speaker in total dry matter production appeared as the growth progressed and it was maintained through maturity. Speaker maintained significantly higher shoot and root dry weight throughout the growth period. However, significant root to shoot ratio revealed only after heading in Speaker. The increased in dry weight before and after heading was significantly higher in Speaker than in IR55419. Speaker maintained significantly higher relative chlorophyll content before and after heading. Moreover, relative growth rate (RGR) was significantly higher before and after heading in Speaker. The higher AGR in Speaker was attributed by the higher net assimilation rate (NAR) and larger leaf area index (LAI) before and after heading than in IR55419 suggesting higher photosynthetic efficiency although the physiological mechanisms remains to be investigated.