Evaluation of the Effects of Drought Stress and Nitrogen-Sulfur Fertilization on Productivity and Yield Parameters of Spring Wheat

The combined effects of increasing sulfur (S) fertilization rates and drought stress on the yield and compositional parameters of spring wheat on Chernozem soil were studied. In a greenhouse pot experiment, increasing S doses (22.4, 28, 56 kg S/ha) were used with a constant nitrogen (N) dose (112 kg N/ha), resulting in different N:S ratios (1:0.2; 1:0.25; 1:0.5). Water supply treatments included optimal irrigation, maintaining 60% of field capacity, and a water stress treatment where irrigation was withheld until wilting symptoms appeared, followed by irrigation to 40% of field capacity. By measuring the dry biomass production; plant N and S%; and inorganic sulfate-S content, the N/S ratio; harvest index (HI); and organic S, N and S uptake were determined. Our findings indicate that, under water stress, S incorporation into plants is limited, as it tends to remain in an inorganic form. Furthermore, results showed an increase in the N/S ratio under drought conditions, suggesting that drought stress impedes S uptake more significantly than N uptake. In this experiment, fertilization with 112 kg N/ha and 56 kg S/ha (N:S = 1:0.5) proved to be most effective under adequate water supply. In this treatment, grain N and S% were 1.80% and 0.18%, respectively.