The effects of nano-iron on volatile compounds and phytoestrogens in the Flowering Process of Trifolium pratense

Abstract

Fe fertilizer is usually used to accelerate the growth and development of plants and trigger the accumulation of specific secondary metabolites to promote resistance and/or immunity of plants. Flowering is a critical process for plant growth and species continuation in angiosperms. However, little is known about the effect of Fe fertilizer on the flowering process. The volatile organic compounds (VOCs) and phytoestrogens in five flowering stages of Trifolium pratense with three Fe treatments (0, 1 and 2 g/mu) were evaluated in the study, which is a very important leguminous forage worldwide. The results showed that Fe contents in flowers dramatically increased with Fe concentrations. It was interesting that the highest Fe content of the flowers was in the senescent stage with 1 g/mu Fe treatment. The control group (CK) in the bud stage had the lowest amount of volatile organic compounds, but nano Fe significantly increased the amount of volatile organic compounds in the bud stage with various aromas. Alkane had the highest relative abundance among VOCs, accounting for more than 45–81%, and gradually increased in pace with the flowering process. Furthermore, nano Fe fertilizer promoted the accumulation of phytoestrogens. The main secondary metabolites exhibited obvious continuity throughout the whole flowering process. The results of the partial least squares discriminant analysis model illustrated that nano Fe fertilizer significantly changed the highly related VOCs and phytoestrogens in different flowering stages. The concentration of 1 g/mu was considered as a cost-effective agronomic measure to promote effectively reproduction and improve the contents of secondary metabolite in seed.