Advantages of Amending Chemical Fertilizer with Plant-Growth-Promoting Rhizobacteria under Alternate Wetting Drying Rice Cultivation

Chemical fertilizer (CF) is necessary for optimal growth and grain production in rice farming. However, the continuous application of synthetic substances has adverse effects on the natural environment. Amending synthetic fertilizer with plant-growth-promoting rhizobacteria (PGPR) is an alternate option to reduce CF usage. In this study, a field trial was undertaken in southern Taiwan. We aimed to investigate the effects of reducing CF, either partially or completely, with PGPR on the vegetative growth, biomass production, and grain yield of rice plants cultivated under alternate wetting and drying (AWD) cultivation. In addition, we aimed to determine an optimal reduction in CF dose when incorporated with PGPR for application in rice cultivation under AWD. The trial consisted of four treatments, namely, 0% CF + 100% PGPR (FP1), 25% CF + 75% PGPR (FP2) 50% CF + 50% PGPR (FP3), and 100% CF + 0% PGPR (CONT). A randomized complete blocked design (RCBD) with three replicates was used. A reduction in CF by 25-50% with the difference compensated by PGPR significantly (p <= 0.05) influenced the crops biomass production. This improved the percentage of filled grains (PFG), and the thousand-grain weight (1000-GW) of treated plants by 4-5%. These improvements in growth and yield components eventually increased the grain yield production by 14%. It is concluded that partial replacement of CF with PGPR could be a viable approach to reduce the use of CF in existing rice cultivation systems. Furthermore, the approach has potential as a sustainable technique for rice cultivation.