Download or read book The Grapevine Nitrogen Economy written by Shaunt Edward Oungoulian and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The nitrogen status of grapevines is of critical importance for the wine industry. Many investigations have shown that nitrogen availability in the vineyard can affect vigor, yield and fruit quality, all of which have been implicated in affecting overall wine quality. Additionally, the nitrogen content of the fruit, since nitrogen is utilized by the yeast in fermentation, can affect must fermentation rate and duration and thereby wine quality. Many studies have investigated the nitrogen composition in grape berries and musts. Free amino acids have been identified as the primary form of nitrogen in these organs. Additionally, the effects of cultural practices such as fertilization and rootstock choice are known to influence grape berry nitrogen composition. However, there has been relatively little investigation into the nitrogen composition, specifically amino acid (AA) nitrogen, in other grapevine organs. This study investigated the effects of rootstock selection on the organic nitrogen composition of grapevine roots. Twofold differences in total amino acid analyzer (AAA) measured soluble nitrogen species were observed among various rootstock genotypes, with arginine identified as the dominant form of organic nitrogen. Similarly, a twofold variability of AAA measured insoluble, and likely protein, nitrogen species was observed, with arginine also identified as the dominant form of organic nitrogen. Much higher variability in the concentration and profile of AAA measured nitrogen species was observed in the berries themselves. Two amino acid accumulation phenotypes were identified among V. vinifera cultivars: hyper proline accumulators that accumulate high levels of proline relative to the total AAA measured soluble nitrogen species and moderate proline accumulators that accumulate lower levels of proline and higher levels of arginine relative to the total AAA measured soluble nitrogen species. These phenotypes appear to be genetically fixed, as variability in cultural practices, geographic location, or vintage has not been observed to change a given cultivar's AA phenotype, suggesting genetic differences in various biochemical synthesis and accumulation pathways.