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Utilization of Nitrogen to Sulfur Ratio for Evaluating Sulfur‐Containing Amino Acid Concentrations in Seed of Glycine max and G. soja 1
Author(s) -
Radford R. L.,
Chavengsaksongkram C.,
Hymowitz T.
Publication year - 1977
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1977.0011183x001700020011x
Subject(s) - glycine soja , biology , methionine , kjeldahl method , cystine , glycine , nitrogen , zoology , sulfur , botany , amino acid , biochemistry , chemistry , cysteine , organic chemistry , enzyme
A screening procedure using the ratio of total N to total S (N/S) was developed for indexing methionine and cystine concentrations in seed of soybeans— Glycine max (L.) Merrill—and its putative ancestor G. soja Sieb. and Zucc. Percent N was determined by the standard micro‐Kjeldahl procedure. Total S was analyzed by reducing SO 4 ‐S (from nitric acid‐perchloric acid digestion) to H 2 S and then percent S was determined by titration with HgCl 2 using dithizone as an indicator. The N/S values found in the soybean genetic type collection ranged from 24.5 to 15.4 with the mean being 18.3. The N/S values found in plant introductions of G. max that were formerly known as G. gracilis Skvortz. ranged from 20.1 to 16.3 with the mean being 18.4. The N/S values found in plant introductions of G. soja ranged from 21.5 to 12.5 with the mean being 17.5. Results from a 2‐year investigation on the effect of growing seasons on the N/S ratios in seed revealed that the N/S ratios were quite stable from year to year in G. max and somewhat less stable in G. gracilis and G. soja . Attempts to identify the source of variation indicated that the variation in N/S values in seed of G. gracilis and G. soja largely were due to N content. The reasonably high correlation coefficients between mg of methionine and cystine with percent S (r = 0.846) and g methionine and cystine/16 g N with N/S ratios (r = 0.787) suggest that rapid screening for N and S Glycine germplasm would be helpful in directing investigators to lines that warranted further study.