Estimation of Sulfur in Grain by X-Ray Fluorescence Spectrometry and Its Relation to Sulfur and Aniino Acids of Field Crops
1984
Maranville, J. W. | Mattern, P. J. | Clark, R. B.
Energy dispersive X-ray fluorescence spectrometry (EDXRF) is a rapid method of multielement analysis which includes S. Since most S in grain is associated with the S amino acids in protein, a measure of total S concentration might indicate, in part, grain nutritive value. A study was conducted to determine if total S measured by EDXRF was associated with concentration of cystine, cysteine, and methionine of corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] grain. Results showed that total S when determined as a percent of dry weight was positively correlated with S amino acids in the crops investigated. The highest correlation for methionine with S was for wheat (r = 0.913) followed by sorghum (r = 0.893), corn (r = 0.854), and soybean (r = 0.796). Correlations with S were equally as high for cysteine + cystine in these crops. Total S correlated highly with protein levels in sorghum, wheat, and soybean, but not in corn. Sulfur as a percentage of protein was strongly associated with the S amino acids calculated as a percentage of protein in corn, but not in sorghum, wheat or soybean. The N/S ratio was negatively and significantly correlated with S amino acids (percentage of protein) only in corn and soybean. Total S measured by EDXRF and calculated as percent of dry wt appeared to be a reliable indicator of S amino acid content in the crops studied. Total S may be used as an index of S amino acids in grains when crops are being screened for that character in plant breeding programs.
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