Effect of nitrogen fertilisation and irrigation on phenolic content, phenolic acid composition, and antioxidant activity of winter wheat grain.

Abstract

Understanding the variance of antioxidant in wheat grain responses to irrigation and nitrogen (N) fertiliser management will improve the nutrient quality of wheat grain. Four N rates (0, 180, 240, and 300 kg ha(-1)) combined with irrigation times (I0, no irrigation; I1, jointing time irrigation; I2, jointing + flowering time irrigation), were used to determine the effect of N fertilisation and irrigation on total phenolic content (TPC), phenolic acid composition, and antioxidant activity (AOA) of wheat grain. Irrigation, N fertilisation and their interactions had significant effect on TPC, total flavonoid content (TFC), AOA, p-coumaric acid (PCA), as well as vanillic acid (VA) and chlorogenic acid (CA). I1 N300 treatment had the highest TPC at Zhengzhou and Wenxian (1451.5 µg g(-1) and 1397.9 µg g(-1), respectively) location, while I1 N240 resulted in the highest TFC (0.75 mg g(-1)) and VA (19.77 µg g(-1)) at Wenxian. TPC, TFC, AOA, ferulic acid (FA), PCA and VA increased with N application rate (from 180 to 300 kg N ha(-1)). An appropriate irrigation and N management improved antioxidant content and AOA in wheat grain. Generally, I1 N240 and I1 N300 treatment resulted in the higher TPC, TFC, AOA, as well as phenolic acid, i.e. FA and VA.