Effects of Phosphorus-Solubilizing Rhodopseudomonas palustris VNW64, VNS89, TLS06, and VNW02 on Phosphorus Nutrient Dynamics and Yield of Hybrid Maize Grown in In-Dyke Alluvial Soil

Phosphorus (P) fixation in in-dyke alluvial soils can limit maize productivity and reduce P fertilizer-use efficiency. This study evaluated whether P-solubilizing purple nonsulfur bacteria (PNSB), comprising Rhodopseudomonas palustris VNW64, VNS89, TLS06, and VNW02, could improve soil P dynamics, P uptake, growth, and yield of hybrid maize. A pot experiment using soil from Chau Phu commune, An Giang province, Vietnam, was arranged in a randomized complete block design with ten treatments and four replicates. Treatments combined recommended N and K fertilization with 100, 75, 50, or 25% of the recommended P rate, with or without PNSB, plus unfertilized controls. PNSB supplementation increased soil pH, NH4+ concentration, and soluble P content, while reducing insoluble Al-P, Fe-P, and Ca-P fractions. Inoculated treatments also enhanced P uptake, biomass accumulation, growth traits, SPAD index, yield components, and grain yield compared with the corresponding non-inoculated treatments. Applying 75% of the recommended P rate with PNSB produced higher grain yield and P uptake than full P fertilization without PNSB. Thus, R. palustris VNW64, VNS89, TLS06, and VNW02 can reduce chemical P fertilizer input by 25% while sustaining or improving hybrid maize performance in in-dyke alluvial soil.