Nitrogen and sulphur fertilisation affecting soybean seed spermidine content

Abstract

Soybean (Glycine max [L.] Merr.) is the major protein and oilseed crop worldwide. Soybean seeds are a rich source of spermidine and other polyamines, which have various positive health effects such as anti-ageing, antioxidant or anti-inflammatory properties. Beside its macro-nutritional composition, soybean contains various bioactive compounds adding health-protecting functional properties to soy-based foods. The present research is based on the hypothesis that soil application of nitrogen and sulphur might stimulate soybean seed polyamines in addition to agronomic traits. As effects of fertiliser application on spermidine were unknown before, a respective pot experiment was carried out, applying ammonium sulphate or urea at nitrogen levels of 0, 1 or 3 g per 5 kg soil in two soybean cultivars. The results indicated that cultivars differed significantly in seed yield, thousand seed weight (TSW) and oil content. For both tested cultivars, seed yield, TSW and contents of protein and spermidine were lowest in the unfertilised treatment. The spermidine content increased significantly after the application of each dose of ammonium sulphate (280 - 283 mg kg-1 DM) or the lower dose of urea (267 mg kg-1 DM) as compared to the unfertilised control (228 mg kg-1 DM). The contrast in spermidine levels between non-sulphur (256 mg kg-1 DM) and sulphur (282 mg kg-1) treatments was significant as well, whereas no significant effects were found for the spermine content. The results demonstrate that an application of appropriate doses of nitrogen and sulphur can increase the content of spermidine in soybean seeds apart from affecting other traits. © 2018, Polish Society Magnesium Research. All rights reserved.