PCC January/February 2018

Table 3 Summary of yield and Ravaz Index of 2016 and 2017.
Year 2016 2017 Sum
Treatment Yield (t/acre) Ravaz Index Yield (t/acre) Ravaz Index Yield (t/acre)
(kg/kg)
(kg/kg)
0 cluster/shoot 0 NA 16.6 NA 16.6
1 cluster/2 shoots 5 8.3 19 NA 24.0
1 cluster/shoot 6.6 16.1 13.9 NA 20.5
Control 7 19.9 13.3 NA 20.3
Figure 3 Weekly TSS (Brix) accumulation starting at
the onset of veraison in 2016 with the means represented
from one cluster per two shoots (1/2), one cluster
per shoot (1) and non-thinned (control).
Figure 4 Total soluble solids (Brix) decreased as Ravaz index
increased beyond 10, and the vines became increasingly overcropped
in 2016. Ravaz Index 10
may indicated overcropping,
whereas Ravaz index 10 may also be a reasonable
threshold for these young vines.
Vines with a Ravaz Index >10
in 2016 had the least amount
of berry TSS at the harvest of
2016 and the lowest yields in
2017 (Table 1 and Table 2, page
22). Specifically, a higher Ravaz
Index (>10) in 2016 resulted
in less amount of berry TSS in
2016 and less yield in 2017 (Figure 4
and Figure 5). Thus, overcropping the
first year, Ravaz Index >10, may inhibit
TSS accumulation in the current
growing season, and also limit yield
the following season.
Thus, newly planted Pinot gris on
quadrilateral cordons might benefit
from cluster thinning, e.g., one cluster
per two shoots at the second leaf, in
order to achieve a Ravaz Index ≤10
which may help to achieve long-term
yield and economic sustainability for
the newly planted vines in the SJV.
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Figure 5 Vines with a Ravaz Index >10 in 2016
had lower yields in 2017, with yield decreasing
as Ravaz index increased. Ravaz Index