<i>Bacillus subtilis</i> –containing biostimulant improves salt stress tolerance of creeping bentgrass

Abstract Turfgrass is increasingly experiencing salt stress due to the accelerated salinization of agricultural lands and increasing demand for use of reclaimed or other secondary saline water for irrigation of turfgrass landscapes. Proper application of microbial biostimulants may alleviate salt stress‐induced injury of turfgrass and other crop plants. This growth chamber study was to investigate effects of a Bacillus subtilis –containing biostimulant on salt stress tolerance in creeping bentgrass ( Agrostis stolonifera ). There were five treatments, including non‐salt and salt controls, and three rates (0.32, 0.64, and 1.28 mL m −2 ) of the biostimulant with four replications, and treated grass was subjected to salt stress (sodium chloride [NaCl], 8 ds/m). The results showed that foliar application of the biostimulant improved leaf color, green leaf percentage, leaf chlorophyll content, photochemical efficiency, and leaf antioxidant enzyme superoxide dismutase activity when compared to the salt control. The treatments also increased root biomass, root viability, leaf potassium (K), and magnesium (Mg) content. The treatment at the high rate (1.28 mL m −2 ) tended to have greater positive effects on salt stress tolerance when compared to the low rate (0.32 mL m −2 ). The results of this study suggest foliar application of the Bacillus subtilis –containing biostimulant at 1.28 mL m −2 could improve salt tolerance by improving plant growth, photosynthetic function, and antioxidant systems in creeping bentgrass.