Optimization of PGPR and silicon fertilization using response surface methodology for enhanced growth, yield and biochemical parameters of French bean (Phaseolus vulgaris L.) under saline stress

Increasing the yield performance of marketable horticulture crops and products using sustainable approaches has been the emergence of the 21st century. In this study, optimization of PGPR consortia and silicon fertilizer for enhanced growth and crop yield of French bean (Phaseolus vulgaris L.) was performed against saline stress. A central composite design (CCD) of RSM having face-centered (k = 1) configuration and 17 triplicated runs was designed for P. vulgaris cultivation experiments. A quadratic model having three levels of PGPR dose (X-1: 8 x 10(7), 4.5 x 10(7), and, 1 x 10(7) cfu/g) and silicon dose (X-2: 15, 10, and 5 g/kg soil) was used to optimize P. vulgaris plant height (Y-1; cm), pod length (Y-2; cm), pod yield/plant (Y-3; g), total chlorophyll content (Y-4; TCC: mg/g fwt.), superoxide dismutase (Y-5; SOD: mu/mg), and catalase (Y-6; CAT: mu/mg) activities. The results showed that the two selected factors (X-1 and X-2) had a significant influence on the selected response variables. Statistical analyses explained coefficient of determination (R-2<0.84), P-value (<0.05), F-value (>0.05), and not-significant lack of fit values (>0.05) supportive for the validation of prediction models. The maximum plant height (40.10 cm), pod length (18.01 cm), pod yield/plant (67.95 g) and TCC (4.40 mg/g fwt.), SOD (120.19 mu/mg), and CAT (84.21 mu/mg) activities were at optimized doses of PGPR (5.52 x 10(7) cfu/g) and silicon (10.90 g/kg). The finding of this study suggested that the combined application of PGPR and silicon fertilizer can enhance growth, yield and biochemical activity of P. vulgaris in saline soils.