Starch concentrations in grapevine leaves, berries and roots and the effect of canopy management.
Hunter, J. J., Ruffner, H. P. and Volschenk, C. G.
South African Journal for Enology and Viticulture Year: 1995 Vol: 16 Issue: 2 Pages: 35-40 Ref: 45 ref.
1995
บทคัดย่อ
Diurnal and seasonal starch changes in leaves, berries and roots of grape cv. Cabernet Sauvignon on 99 Richter rootstock and the effects of canopy management (a combination of suckering, shoot positioning and 33% defoliation) on these processes were investigated under field conditions at Nietvoorbij, South Africa. An increase in starch concentration of basal leaves occurred from the morning to the afternoon during the most active vegetative growth period (up to veraison), indicating a proportional change in storage or export of assimilates between day and night. During later developmental stages diurnal starch levels slightly declined or remained the same. Seasonally, leaf starch remained relatively stable until veraison, whereafter it increased, reaching its highest concentrations at the postharvest stage. Canopy management generally increased leaf starch concentrations. Berries contained no significant amounts of starch. Root starch concentrations were usually higher than those of leaves. Diur
nally as well as seasonally, root starch accumulation patterns coincided with those of leaves, indicating a close relationship between source and sink tissue. Canopy management resulted in stable diurnal root starch concentrations without affecting the daily mean starch level; afternoon values of treated vines were, however, generally lower. The results imply that carbohydrate supply and starch-synthesizing enzyme systems were not limited by manipulating the canopy and decreasing foliage. However, starch accumulation in roots seemed to be delayed by canopy manipulation, particularly late in the season. This indicates a shift in sucrose partitioning and its utilization in roots and other sink areas, e.g. the berries, when the canopy is manipulated.