Variation of Total Amino Acid Content in Wheat Grains in Relation to Fertilization

Abstract

The aim of this study was to evaluate the quality of wheat grains, in terms of total amino acid (TAA) content, in relation to fertilization. The field experiments were located at the University of Life Sciences “King Mihai I” from Timisoara, during 2018 – 2022. The 'Alex' wheat variety was cultivated. Nitrogen (N, ammonium nitrate) fertilization was done in five doses: 0, 50, 100, 150, and 200 kg ha^-1 a.s. (a.s. – active substance). The Super Fifty (SF) biofertilizer was applied foliarly, at each N level, in doses: 0, 1, 2, 3, 4, 5 L ha^-1. The total amino acid content (TAA, mg kg^-1) ranged from 962.09±21.66 mg kg^-1 (N0, SF0) to 1388.06±52.14 mg kg^-1 (N200, SF2). Comparative analysis of the data indicated statistically significant differences between the mean values ​​(ANOVA Test), between the median values ​​(Kruskal-Wallis Test), and between certain experimental variants with nitrogen associated with the foliar biofertilizer (N200 and N0, N200 and N50, N150 and N50, respectively N100 and N50). The direct and interaction effect of the two fertilizers on the TAA index was described by a polynomial model, with R² = 0.556, p<0.001. From the values ​​of the equation coefficients and the graphic models (3D, isoquants), divergent action of the N and SF factors on the formation and variation of TAA was observed. Multivariate analysis explained how low nitrogen doses (N0, N50) were associated with high concentrations of the SF biofertilizer (SF4, SF5) and medium-high N doses (N100, N150, N200) were associated with moderate concentrations of the SF biofertilizer (SF2, SF3) in the formation of total amino acid content values ​​(TAA, mg kg^-1).