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South African
Wine Lab Association:

Quantitative Investigation of Leaf Photosynthetic Pigments during Annual Biological Cycle of Vitis vinifera L. Table Grape Cultivars

R.V. Filimon1*, L. Rotary1, R.M. Filimon2

Variations in chlorophyll a/b and chlorophyll/carotenoid ratios are indicators of senescence, stress or
damage to the photosynthetic apparatus and affect the normal course of plant biological processes. The
aim of this work was to investigate the chlorophyll (a and b) and carotenoid content and ratios in the
leaves of four Vitis vinifera L. table grape cultivars in the main phenophases of the annual biological
cycle. During the annual cycle, the moisture content of the leaves decreased significantly (up to 21%),
along with a reduction in leaf area and perimeter. Chlorophyll a and b showed a continuous accumulation
until grape véraison, with lower values of the Chl a/b ratio at the beginning of the vegetative period.
Carotenoids continued their biosynthesis until grape ripening (for another 30 days), at which stage there
was a significant decrease in the chlorophyll/carotenoid ratio (2.62 ± 0.31). At véraison, peroxidase had
the most intense activity (0.20 to 0.51 U/mg), possibly because of involvement in chlorophyll degradation,
while total phenolic content started to decrease. Grape véraison could be regarded as the starting point of
foliage senescence. Moreover, the relationship between total chlorophyll (by extraction) and chlorophyll
content index (non-destructive method) was very significant (R2 = 0.92). These results contribute to a better
understanding of foliar pigment dynamics and the timing of their decline in order to define the behaviour
of table grape cultivars during the annual biological cycle.

Chlorophyll, carotenoids, peroxidase, leaf senescence, non-destructive method

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