Effect of Late 15N-Fertilization and Water Deficit on Allocation into the Gluten of German and Mediterranean Spring Wheat Cultivars

Abstract

In a split N-application system, the objective was to quantify N/15N in gluten and non-gluten proteins after the late application of 30 or 60 kg N, whereby 10% of the third split was applied as 15N. This fertilization was combined with a reduced water supply for 21 days (well-watered (ww); water deficit (wd)). German spring wheat cultivars, Elite wheat Taifun, Quality wheat Monsun and cultivars from the Mediterranean territory, Golia, Gönen, were examined. The protein content in gluten was for 30 kg N, ww, similar for Taifun, Golia, and Gönen, but markedly lower in Monsun (231, 245, 247, 194 mg protein/g DM). The water deficit increased the protein content in the gluten of Golia and Gönen and was higher than that of Taifun and Monsun (297, 257, 249, 202 mg protein/g DM). Fertilization of 60 kg N, ww, did not result in any change in the protein content in gluten and differences between the cultivars were not detectable. The 15N protein in gluten was for 30 kg N, ww, markedly higher in Gönen (2.32 mg 15N protein/g DM), compared to Golia and Monsun (1.93, 1.50 mg 15N protein/g DM), and similar in Taifun (1.64 mg 15N protein/g DM). 15N fertilizer uptake into gluten was stimulated by water deficit for 30 and 60 kg N, leading to significantly increased 15N protein in Golia and Gönen, (2.38, 2.99, 4.34, 5.87 mg 15N protein/g DM). Fertilization of 60 kg N led to a proportional two-time increase in the 15N gluten protein of the four cultivars, in ww and wd plants. Assessed on the basis of 15N fertilizer allocation under wd conditions into gluten proteins, Golia and Gönen have a stronger sink activity, compared to Taifun and Monsun.