Estimation of Sulfur in Grain by X-Ray Fluorescence Spectrometry and Its Relation to Sulfur and Aniino Acids of Field Crops1
- J. W. Maranville,
- P. J. Mattern and
- R. B. Clark2
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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