Genotypic Differences and Nitrogen Uptake of Lowland Rice (Oryza sativa L.) under Two Production Systems and N Application

Climate change has been causing low yield in rice production. In order to counter the negative effects of climate change in rice production, it is important to choose a suitable variety and production system, as well as application of nitrogen. This study sought to determine the agronomic and yield performance of inbred and hybrid rice under System of Rice Intensification (SRI) and conventional production systems, as well as evaluate the Nitrogen Use Efficiency (NUE) of these varieties under two production systems and N application. The experiment was laid out in a nested design in RCBD with varieties as the main plot and N application as subplot -1 -1 (0 kg N ha and 90 kg N ha ) under two production systems. Inbred rice grown under SRI headed earlier than hybrid rice in similar condition and both varieties in the conventional production system. Irrespective of production system, hybrid variety and those applied with N were taller than inbred without N application. Regardless of the variety and levels of N applied, lowland rice grown under SRI produced the most productive tillers, heaviest1,000 grains, heaviest root pulling resistance (RPR), and highest leaf area index(LAI). In terms of N levels, grain yield was higher when 90 kg of N was applied in both production systems than without N. Both varieties had -1 comparable grain yield when applied with 90 kg N ha . Highest NUE was obtained -1 under SRI with application of 90 kg N ha and under conventional system without N application. Thus, rice grown under SRI had better utilization of applied N. Meanwhile, water supplied in SRI was reduced by 32% compared to the conventional production system.