Effect of foliar application of potassium fertilizers on soybean plants under salinity stress

Soybean, one of the major food and fodder crops, yield is significantly reduced by different abiotic and biotic stresses, and salinity is one of the major abiotic stresses. The research objective of this study was to investigate the effect of foliar application of potassium chloride and potassium sulfate fertilizers at the early growth stage of soybean under medium (6 dS/m) and high (12 dS/m) salinity stresses. The effect of fertilizer application was measured on the bases of plant growth, levels of antioxidant activities, total polyphenol, flavonoid, chlorophyll, and carotenoid contents. Potassium sulfate showed better positive effect on the antioxidant activities, polyphenol, flavonoid, carotenoid, and chlorophyll contents compared to those of potassium chloride although the contribution was not noteworthy in comparison to the fertilizer unsprayed plants. The results of this study implied that foliar applications of 2.5% potassium fertilizers could not help reduce the negative effect of salinity stress at the early stage of soybean growth. This study suggests further researches using different concentrations of fertilizers at different plant growth and development stages.