The impact of foliar applied zinc and iron on quality of soybean

For optimum growth and yield production, plants need all soil minerals to be available in adequate level, and unsuitable soil conditions can restrict root's ability for uptake of minerals nutrient. For that matter, foliar sprays can be the best option for plants to benefit from nutrients. Field experiments with split-split plot design with three replications were conducted in 2018 and 2019 to determine the effects of foliar spraying zinc and iron treatments on some quality parameters of soybean (Glycine max L.) plants under calcareous soil with high pH conditions. Varieties (Arisoy, Bravo, Nazlican) were placed in main plots, growth stages of the soybean (V3, R1, R3) in sub plots and foliar fertilizers (Zn, Fe, Zn + Fe) in sub-sub plots. Foliar application of iron and zinc increased oil and protein content per soybean seed at different stages of growth in contrast to control (non-fertilizers) groups. The highest protein contents (33.61%) and oil contents (22.02%) were obtained from Zn treatment in both years. However, Zn + Fe mixture (102.25 kg da−1) was more efficient on oil yield in both years. It was observed that two-year average of polyunsaturated fatty acids was 58.93% (linoleic 50.13%; linolenic 8.80%), monounsaturated fatty acid was 24.83% (oleic), and saturated fatty acids were 14.68% (palmitic 11.82%; stearic 2.86%). Foliar Zn + Fe mixture spraying can be recommended to get high oil yield, and foliar Zn spraying for oil and protein contents from soybean based on this study.