Phenological-based foliar nutrient management enhances photosynthesis and yield in soybean

Soybean crops require adequate nutritional management throughout their development to maximize physiological performance and grain yield. Although foliar fertilization is widely used as a complementary strategy, information regarding nutrient application according to soybean phenological stages remains limited under tropical field conditions. Therefore, this study evaluated the effects of progressive foliar nutrient management applied at different soybean growth stages on physiological performance, nutritional status, and grain yield. Field experiments were conducted over two years in Rio Verde, Goiás, Brazil. Treatments consisted of increasing foliar nutritional management programs: T1 (control), T2 (Mn-EDTA), T3 (T2 + N, P, Mg, S, B, Ni, Co, Mo, Zn, K, amino acids, and Cu-EDTA), T4 (T3 + K, Mg, S, Mn, Zn, B, and Cu), and T5 (T4 + Mg, Zn, and Se). Plant biometry, chlorophyll content, photosynthetic parameters, leaf nutritional status, nutrient export by grains, and grain yield were evaluated. Progressive foliar nutrient application promoted significant physiological and productive gains in soybean plants, with T5 showing the best overall performance. Compared with the control treatment, grain yield (5,509 kg ha−1) increased by 55.3%, photosynthetic rate by 12.5%, and chlorophyll content by approximately 7%. In addition, improvements in plant structure and nutrient accumulation were observed. The results demonstrate that progressive foliar fertilization based on soybean phenological stages is an effective strategy to enhance soybean physiological efficiency and grain yield, representing a practical alternative for increasing productivity and profitability under Brazilian tropical field conditions.