Effect of iron and zinc spraying and harvesting times on germination and some biochemical characteristics of soybean cultivar Williams 82

In order to study the changes of seed germination of soybean (Glycine max) and some biochemical characteristics, a factorial experiment as randomized complete block design was conducted at the Agricultural and Natural Resources Research Center of Ardabil Province (Maghan) in 2020-2021. Treatments included 2 spraying factors as iron and zinc sulfates besides three harvesting times: green pod, physiological maturity and dry mature pod. According to the results, interactions of spraying and harvesting time were significant on grain yield and protein percentage, and the highest amounts of both traits were obtained by applying zinc sulfate at dry mature pod. Seed oil content was affected by both treatments so that, the highest amount was obtained at the green pod at rate of 21.4% and zinc sulfate had the greatest effect on grain oil percentage at rate of 20.3%. Furthermore, interaction of spraying and harvesting time was significant on seed Fe and Zn contents and results showed that the highest amount of seed Fe (121.6 mg/kg) was achieved by iron sulfate and that of seed Zn (91.1 mg/kg) by zinc sulfate, both at the physiological maturity. Seed germination was also affected by interaction of spraying and harvesting time and the highest rate (96.6%) was observed at dry mature pod by applying zinc sulfate. In general, Zn consumption increased germination percentage, grain rate, seed oil percentage and grain yield, and iron consumption improved grain protein. The physiological maturity and dry mature pod harvestings improved the values of measured traits except the seed oil.