Amino Acid Composition of Grain Protein of Maize from Matched Pairs of Organic and Conventional Fields

摘要

Measurements are reported of the amino acid composition of protein from maize (Zea mays L.) grain raised on fourteen pairs of organic and conventional fields which were matched for location, cultivar, planting date, and soil type. The amino acid composition of the organically raised maize grain was superior with respect to concentrations of lysine and methionine, two essential amino acids which are in low concentration in maize. However, because of higher protein yields in conventionally grown grain, amino acid yields per unit area were significantly higher in grain from the conventional fields, except for methionine, for which there was no significant difference. Differences in yield, protein concentration, and amino acid composition between organic and conventional maize were similar in direction, although not necessarily in magnitude, to reported differences between nitrogen-fertilized and non-nitrogen-fertilized maize. At least part of the difference between organic and conventional maize is consistent with a greater accumulation of zein in conventionally raised maize grain. Results presented in this paper suggest that organic maize yields could be increased by modest applications of nitrogen.