Nutritional and morphophysiological responses of soybean to micronutrient fertilization in soil

Abstract

Micronutrient fertilization is essential to meet the nutritional deficiency of plants, providing the full development of crops. The aim of this work was to evaluate the effects of fertilization with micronutrients applied in the soil on the nutrition and morphology of soybean plants. The experimental design was completely randomized, with four replications. The treatments consisted of fertilization with micronutrients applied to soil to reach three levels of availability of B: low (<0.15 mg dm-3-control), good (0.61 mg dm-3) and high (> 0.90 mg dm-3). For this, the following values were applied: 0.00 (control), 56.67 and 211.11 kg ha-1 of the fertilizer containing 1.8% B, 0.85% Cu, 2% Mn and 9% Zn. Fertilization with the good and high treatments did not affect the uptake of B, but increased the Cu and Mn content, and reduced the Zn content in the plants. Higher plants with greater leaf expansion were observed in the high treatment, however, this did not influence the soybean grain yield. In the control, the physiological activity revealed smaller A, whereas gs and Ci were more effective; reverse effect was observed with high treatment. Fertilization with micronutrients in the soil affects the nutritional status and the photosynthetic activity of the plants due to the imbalance in the concentrations of B, Cu, Mn and Zn supplied with the fertilizer, reflecting in the absence of gains in the production of soybean grains. Highlighted Conclusions 1. Fertilization with micronutrients in the soil using as criterion the reach of three levels of availability of B does not increase the production of biomass and grains, despite ensuring foliar contents of B (Ȳ= 40.40) and Cu (Ȳ= 23.06) suitable for soybean cultivation in the Cerrado. 2. The inequity in the concentrations of B, Cu, Mn and Zn supplied with fertilizer affects the physiological performance of soybean plants.