Abstract
Glucose, fructose, sucrose, malate, tartrate, and 22 free amino acids ware determined in `Thompson Seedless' grape leaves during the first 36 days of growth and throughout the growing season.
The glucose and fructose content of leaves increased 3-to-5-fold between the second and third weeks after budburst and remained high until senescent. Sucrose of immature leaves was generally less than glucose and fructose. During the latter part of the growing season, sucrose was the main sugar in all leaves.
The tartrate content increased very rapidly during leaf elongation to a maximum concentration 4 weeks after budburst. Malate continued to increase until late in the season. The amount of both acids decreased rapidly after senescence. Twelve to 27% of the total acidity was accounted for by acids other than tartaric and malic.
Twenty-two free amino acids were identified and measured quantitatively. Proline and threonine predominated during the first week of growth. Free amino nitrogen decreased more than 50% between the 4th and 36th days of leaf growth. Most of the loss was due to decreases in proline, threonine, asparagine, glutamine, β-alanine, valine, serine, pipecolic acid, and tryptophan. In mature leaves the principal amino acids were α-alanine, glutamic acid, aspartic acid, γ-aminobutyric acid, and proline.
- Copyright 1966 by the American Society for Enology and Viticulture
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