The effect of nitrogen fertilization on the composition of the free amino acid pool of poato tubers
- 23 Downloads
When the rate of N fertilization was increased from 36 lbs/acre to 336 lbs/acre, the total amino acid pool in the tubers almost doubled. The increases for individual amino acids ranged from none (tyrosine) to 2.7 fold (glutamic acid + glutamine). Aspartic acid and glutamic acid and their corresponding amides constituted the bulk of the free amino acid pool, and increased from 55% to 65% with increasing fertilization.
Lysine increased by 1.9 times and methionine by 1.4 times with increasing nitrogen fertilization but the relative proportions of lysine in the pool remained unchanged and methionine decreased from 2.2% to 1.6%.
The amino acids could be grouped into four categories with respect to their response to increasing nitrogen levels: those giving almost no response (tyrosine and phenylalanine), those giving full response at low levels of N (amino acids of the serine and pyruvate families), those giving full response at a higher but intermediate level (amino acids of the aspartate family), and those which responded to the highest level of fertilization (glutamic acid + glutamine).
The gas chromatographic method used in this study for the analysis of free amino acids is discussed.
KeywordsGlutamic Acid Free Amino Acid Potato Tuber AMERICAN Potato Journal Aromatic Amino Acid
Unable to display preview. Download preview PDF.
- 1.Gehrke, C. W., D. Roach, R. W. Zumwalt, D. L. Stalling and L. L. Wall 1968. Quantitative gas-liquid chromatography of amino acids in proteins and biological substances. Analytical Biochemistry Laboratories, Inc., Columbia, Missouri.Google Scholar
- 3.Ogato, S. and Y. Ishizuka. 1967. Variation of nutritional and physical characteristics of crops by crossing. I. Response of cultivated, wild, and hybrid potatoes to nitrogen. Nippon Dojo-Hiryogaku Zasshi 38: 79–84. (C.A. 67:32032 m).Google Scholar
- 5.Roy Choudhury, R. N., A. A. Joseph, K. Indirama, M. Narayana Rao, M. Swaminathan, A. Sreenivasan and V. Subrahmanyan. 1963. Amino acid composition and nutritive value of the proteins of different varieties of potato. Food Science (New Delhi) 12: 255–257.Google Scholar