Enhancing Upland Rice Growth and Yield with Indigenous Plant Growth-Promoting Rhizobacteria (PGPR) Isolate at N-Fertilizers Dosage

Upland rice farming plays a crucial role in ensuring food security in Indonesia. This study aimed to evaluate the impact of plant growth-promoting rhizobacteria (PGPR) isolates on the growth of upland rice. The bioassay and pot experiments were conducted to select the capable isolates of PGPR and to investigate the effect of the PGPR inoculant on the N fertilizer efficiency and agronomic traits of upland rice. The bacterial isolates were identified through a biochemical analysis and tested under controlled greenhouse conditions. The selected PGPR inoculant was formulated as a liquid biofertilizer (LB). The three capable isolates were obtained to fix nitrogen, produce indole-3-acetic acid (IAA), organic acid, and nitrogenase activity and were identified through a biomolecular analysis as Delftia tsuruhatensis strain D9, Delftia sp. strain MS2As2, and Bacillus sp. The application of the LB into the soil at a dose of 10 L ha −1 and 50 kg ha −1 N resulted in a grain yield of 29.81 g pot −1 and a relative agronomic effectiveness (RAE) value of 235.08%, signifying a significant improvement over the conventional method. Several variables, including the number of grains, number of panicles, root length, 1000-grain weight, population of nitrogen-fixing bacteria, and nitrogen uptake exhibited a strong correlation with the grain yield, accounting for 97.80% of the observed variation. These findings show the enormous potential of PGPR isolates, specifically of Delftia tsuruhatensis strain D9, Delftia sp. strain MS2As2, and Bacillus sp., in significantly enhancing the upland rice output in Indonesia. Furthermore, the use of an LB as a biofertilizer in conjunction with nitrogen fertilization provides a viable and sustainable way to increase yields and enhance the overall sustainability of the region’s upland rice farming systems.