Effect of nitrogen (N) fertilizer and foliar-applied iron (Fe) fertilizer at various reproductive stages on yield, yield component and chemical composition of soybean (Glycine max L. Merr.) seed

Nutritional management is an important factor in the success of crop production. However, research on the effects of nitrogen (N) and iron (Fe) application on soybean yield is limited. In order to study the effects of N and Fe application at various reproductive stages on grain yield and quality of soybean seed, an experiment was conducted using a factorial arrangement based on randomized complete block design with three replications at the research farm of Kurdistan University in 2009. The experimental treatments consisted of three different levels of N fertilizer application as follows: 0, 50 and 100 kg N ha-1, and two levels of Fe fertilizer (spray with iron and non-sprayed). Results indicate that the maximum seeds yield was obtained at N1 (303 g m-2) and N2 (328 g m-2) treatments and the highest number of seed per plant was obtained at N2 (128) treatment. Potassium concentration in seed and SPAD chlorophyll value responded to fertilizer treatments and the maximum protein percentage (32.5%) was obtained at N1F1 treatment. This treatment had no significant difference with N1F0, N2F0 and N0F1 treatments. The Fe and N fertilization treatments had no significant effect on Fe, Zn, Ca, Na, Cu and P concentration of soybean seed.Key words: Fe and N fertilizers, seed mineral elements, soybean, yield