Grain Yield and Resource Use Efficiencies of Upland and Lowland Rice Cultivars under Aerobic Cultivation

Aerobic rice has the potential to replace transplanted flooded rice, as rice cultivation is seriously threatened by environmental and social factors. Although the recently released upland rice cultivars have higher drought tolerance, low yield potential of these cultivars makes them less feasible for high-yielding rice planting regions under aerobic cultivation. In this study, typical lowland rice cultivars (Huanghuazhan and Yangliangyou6) were evaluated for grain yield and resource use efficiencies under aerobic cultivation as compared with upland rice cultivars (Lvhan1 and Hanyou3). Averaged across different years, lowland rice cultivars recorded 26.9%, 14.6%, and 26.6% higher grain yield, water productivity, and nitrogen use efficiency for grain production (NUEg), respectively, as compared with upland cultivars. The higher grain yield of lowland rice cultivars under aerobic cultivation was mainly attributed to the higher aboveground biomass and the spikelet number per panicle, along with a higher harvest index and panicle number per unit area with respect to upland rice cultivars. During the entire growing season in aerobic cultivation, rainfall accounted for 60% to 85% of the total water use, which indicates that lowland rice cultivars could make better use of the rainfall because of a longer growth duration and a higher growth potential. In summary, this study suggests that with appropriate irrigation, lowland rice cultivars could grow well and furnish higher yield than the current upland rice cultivars under aerobic cultivation.