Protein and free amino acids in wheat triticum aestivum cultivar cajeme grain as affected by soil types and salinity levels in irrigation water
Labanauskas, C.K.; Stolzy, L.H.; Handy, M.F.
Plant and Soil 59(2): 299-316
ISSN/ISBN: 0032-079X Accession: 006210765
The effects of 4 lysimeter soil series under 3 salinity levels were evaluated for grain yield, wt/1000 seeds, protein, and amino acids in Mexican dwarf wheat (T. aestivum L. cv. Cajeme 71). The soil series consisted of: Holtville clay loam, Greenfield sandy loam, San Emigdio sandy loam and Altamont clay loam. The irrigation water salinity levels were designated: low (2.2 mmho) medium (4.2 mmho) and high (7.1 mmho). No significant differences were found in the amount of grain harvested or 1000 seed weight in the 1976 crop produced on the differential soil series. The yield of the 1977 crop was significantly affected by the soil types. Effects of soil type on the protein amino acids in the grain in both years were similar. Significantly higher protein amino acid levels of histidine, arginine, aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine and phenylalanine were found in the grain grown on Altamont clay loam soil than the other types. The free amino acids in grain from the 1976 and 1977 crops were similarly affected by the soil types, except that the quantitative values of the free amino acids were substantially lower in 1977 than in 1976. The free amino acids significantly influenced by soil types were tryptophane, lysine, arginine, aspartic acid, threonine, serine, glycine, alkanine, valine, isoleucine, tyrosine and phenylalanine. In both years' crops, the sum of the free amino acid fractions was significantly higher in the grain produced on the Altamont soil than on the other soils. Salinity level in the irrigation water did not affect the 1976 crop yield or 1000 seed weight. Although yields of the 1977 crop were significantly reduced by salinity, the 1000 seed weight was not. The sum of protein amino acids was significantly higher in the 1976 and 1977 grain crops irrigated with high salinity water than in low salinity irrigated crops. An increased salinity irrigation water significantly reduced the sum of free amino acid fractions in the 1976 grain crop. Since some of the free amino acids in the 1977 grain crop increased while the others decreased due to the salinity level in the irrigation water, the sum of the free amino acid fractions was not significantly influenced. Significant interactions were found between soil types and salinity levels on free arginine, threonine, serine, glutamic acid and alanine, and also on the sum of the free amino acids in the 1976 wheat grain. In the 1977 wheat grain, there were significant interactions between soil types and salinity levels on the free glutamic acid, valine, leucine, tyrosine and phenylalanine, and on protein serine, glutamic acid, glycine, alanine, and the sum of the protein amino acids. The amounts of essential amino acids expressed as mg of amino acid/g of protein were not affected by the soil types or salinity levels. With the exception of lysine, and possibly threonine and methionine plus cystine, the essential amino acids were present in the grain at concentrations equal to or greater than recommended by WHO and FAO.