Influence of Macronutrient Elements on the Amino Acid Composition of Soybean Plants¹

Abstract

Greenhouse experiments were conducted to study the effects of various levels of N, K, Mg, Ca, P, and S on the concentration of amino acids in soybean plant hydrolyzates. Deficiency and excess amounts of N increased the amino acid contents (µ mole/g dry tissue) in the tops, while in the roots the amino acid contents increased as N concentration increased in the root media. Aspartic acid, arginine, and histidine contents of tops were affected most by N treatments. Although the percent N of potassium deficient soybean tops was higher than those plants receiving potassium, their total amino acid contents were of the same order of magnitude. A negative correlation was found between the aspartic acid content of the soybean tops and the potassium concentration of the nutrient media. Similar results were obtained for plants grown at various Mg levels. Calcium levels had little effect on the concentration of amino acids in soybean plants. Increased arginine and aspartic acid and decreased glutamic, proline, glycine, alanine, valine, and leucine contents were noted with P deficient plants. The total amino acid content was highest at 30 ppm P level. A positive correlation was noted between the total amino acid content of tops and the sulfur concentration of the root media. In general, high amino acid contents were found in plants grown under conditions where the macroad micro‐nutrients were present in sufficient amounts and proper balance.

Effects of sulfur application on yield and composition of soybeans and soil sulfur

“…In fact, total plant uptake of sulfur approaches that of phosphorus yet sulfur is called a "secondary" essential element (18). There are reports that sulfur fertilization does increase cystine and methionine in the seed (10,19). In contradiction.…”

Soybean Amino Acids in Health, Genetics, and Evaluation

“…Perhaps the most considered agronomic factor is soil nutrient availability. Insufficient soil nutrient levels of nitrogen, potassium, phosphorous, sulfur, calcium, and magnesium create poor amino acid profiles in soybean plants [71]. Increased phosphorous rates have been shown to increase the percentage of methionine and tryptophan in seed but had no effect on protein content percentage [72].…”

Response of Nodulated and Nonnodulated Soybean Seedlings to Sulfur Nutrition1

“…Ammonia, amino acids, amides, and nitrate increased and protein decreased in stems of tomato (Nightingale et al, 1932) and sunflower (Eaton, 1941) grown without S. Soybeans abo accumulated ammonia, amides, and amino acids in the stems when grown under S-deficicnt conditions, bu nitrate varied inconsistently (Eaton, 1935). In so•ybean leaves, however, nitrate accumulated and ammonia and amino acids varied inconsistently when th~ plants were grown without S. Similarly, S deficiency had less effect than other nutrient deficiencies on contents of specific amino acids in soybeans (Haghiri, 1966).…”

“…S ULFUR nutrition has long been known to affect contents of nitrogenous constituents in plants (Dykshoorn, Lampe, and Van Burg, 1960;Eaton, 1935Eaton, , 1941Haghiri, 1966;Mertz and Matsumoto, 1956;Mertz, Singleton and Garey, 1952;Nightingale, Schermerhorn, and Robbins, 1932). Ammonia, amino acids, amides, and nitrate increased and protein decreased in stems of tomato (Nightingale et al, 1932) and sunflower (Eaton, 1941) grown without S. Soybeans abo accumulated ammonia, amides, and amino acids in the stems when grown under S-deficicnt conditions, bu nitrate varied inconsistently (Eaton, 1935).…”