The Efficacy of 5-Aminolevulinic Acid-Producing Luteovulum sphaeroides Strains on Saline Soil Fertility, Nutrient Uptakes, and Yield of Rice

Saline soils negatively affect and cause serious problems for rice cultivation. This study aimed to evaluate the efficacy of the purple nonsulfur bacteria (PNSB) capable of secreting 5-aminolevulinic acid (ALA) to reduce soil salinity, improve soil fertility, and enhance rice growth and yield. A two-factorial experiment was conducted in a randomized complete block design with four replications. Factor one was the salinity of the irrigated water, and factor two was the supplementation of the ALA-producing PNSB. The results indicated that watering with saline water above 3‰ led to decreases in plant growth and rice yield compared to the treatments watered with tap water. Application of either an individual strain or the mixture of W01, W14, and W22 ameliorated soil properties and increased total NPK uptake, whereas treatments supplied with the mixed strains reduced total Na uptake (9.50 mg Na pot−1). Supplying the W01, W14, and W22 strains individually or in a mixture enhanced the plant height by 3.51–5.45% and rice grain yield by 14.7–26.2%, compared with those of the control treatment. From the study, the combination of the L. sphaeroides W01, W14, and W22 strains is promising for application in saline or salt-contaminated regions to aid the damages caused by salinity on cultivars there, especially rice. Furthermore, this is a biological approach to ease an environmental problem and improve crop performance, which is supposed to be a trend in the sustainable agriculture.