Author : William Kade Casciato
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (126 download)
Book Synopsis Understanding Natural Cessation of Sugar Import Into Grape Berries by : William Kade Casciato
Download or read book Understanding Natural Cessation of Sugar Import Into Grape Berries written by William Kade Casciato and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Own-rooted grapevines Vitis vinifera L. cvs. Cabernet Sauvignon, Merlot, and Syrah were used in this study to better understand the natural cessation of sugar import into grape berries, as well as the timing of this event. Active sugar import via the phloem increases the sugar content in grape berries. As berry weight fluctuates the concentration of these sugars may increase due to water loss from transpiration or late season dehydration. This two-year study was conducted in 2017 and 2018 in a commercial vineyard located in Benton City, Washington, USA. Grape berry weight, total soluble solids (TSS), and sugar content were measured approximately weekly from the “hard green berry” phase (late lag-phase of berry development) through ripening, along with a host of correlative attributes considered to be standard measurements of quality and maturity, and which are influential when making harvest decisions. These additional measurements included titratable acidity (TA), pH, malate, and glucose + fructose. The principal measurement marking cessation of sugar import into berries, thus indicating the end of phloem influx, is when the total sugar per berry (i.e., sugar content) reaches a final plateau. This plateau can be independent of subsequent changes in TSS (i.e., sugar concentration). The three varieties reached maximum sugar contents varying from 0.26-0.42 grams. Each variety experienced a slowdown and plateau of sugar accumulation around 4 weeks after veraison, sugar content then remained stable until seasons end. Significant weight loss was observed in Cabernet Sauvignon, while Merlot and Syrah showed trends towards weight loss after sugar content reached a plateau. Cabernet Sauvignon lost an average of 13% of total berry weight, Merlot lost an average of 9% and Syrah lost an average 6%. Additionally, increases in TSS after the apex of maximum berry weight can be attributed to a concentration effect, not continued sugar import into grape berries via the phloem. Most of the changes in titratable acidity occurred within the first 3 weeks of ripening. This was characterized by a loss of nearly 85% across each variety and year. pH followed a similar yet inverse trend, rising steadily in the first 3 weeks of ripening.
