March 2018 WINES&VINES 37
PRACTICAL WINERY & VINEYARD GRAPEGROWING
ripening and ripe berries were
pressurized from the peduncle
end, the inward dye movement
was restored (which normally
ceased around the pedicel end
without pressurization).
3
On the other hand, when the
roots of pot-grown vines were pres-
surized, the outward dye movement
from berries was stopped.
4
The re-
sults indicated that the changes in
xylem pressure were the culprit for
the decline in xylem inflow.
What led to changes
in xylem pressure?
The other water-conducting struc-
ture, the phloem, runs side by side
with the xylem. The phloem in-
flow to the berry is regulated by
rates of berry growth, transpira-
tion, respiration and sugar accu-
m u l a t i o n a s w e l l a s s u g a r
concentration of the pedicel
phloem sap. During véraison,
phloem inflow increases due to
the rapid sugar accumulation.
Using a grape berry growth
model, it was estimated that, to
meet the demand of berry sugar
accumulation, the volume of
phloem-inflow must exceed the
water demand for berry growth and
transpiration.
4
After the sugar-water
solution moves to the berry, the
sugars are unbundled from the solu-
tion, and excess water is left behind.
This surplus water may alter the
pressure gradient inside the xylem
and, thus, alter the direction of xy-
lem-flow during berry ripening.
Different sensitivity
to soil-water availability
Studies of grape berry water rela-
tions have revealed that grape ber-
ries have different sensitivity to
soil-water availability, depending
on their developmental stages.
1,3,4
Before véraison, berries are sensi-
tive to water stress and rewatering:
Berries shrink in response to water
stress imposed and recover rapidly
by expanding after rewatering.
VINEYARD MACHINERY SUPPLIERS
Company Phone Website
BDI Machinery Sales Inc. (800) 808-0454 bdimachinery.net
Bettcher Industries (800) 321-8763 bettcher.com
Blueline Manufacturing
and Equipment
(509) 248-8411 bluelinemfg.com
Canycom USA Inc. (888) 450-0381 canycomsales.com
CFM Worldwide (209) 334-6638 cfmworldwide.com
DeJong Products (800) 887-3415 dejongproducts.com
Double A Vineyards Inc. (716) 672-8493 doubleavineyards.com
Dubois Agrinovation Inc. (450) 454-4641 duboisag.com
Earth & Turf Products LLC (717) 355-2276 earthandturf.com
Electrostatic Spraying
Systems Inc.
(706) 769-0025 maxcharge.com
Garton Tractor Inc. (877) 872-2867 gartontractor.com
Green Hoe Co. (716) 792-9433 greenhoecompany.com
H&W Equipment (905) 468-5016 vineyardmachines.com
Infaco USA (925) 371-0796 infaco-usa.com
Kingsburg Cultivator Inc. (559) 897-3662 kci-mfg.com
Koham LLC (307) 337-2810 kohamamerica.com
Lakeview Vineyard
Equipment Inc.
(905) 646-8085 lakeviewvineyard
equipment.com
New Holland Agriculture (717) 725-5209 newholland.com/na
OESCO Inc. (413) 369-4335 oescoinc.com
Pellenc America Inc. (707) 568-7286 pellenc.com
Pygar USA Inc. / Felco (206) 258-2901 pygar.us
Rinieri North America (801) 794-9774 allenintl.net/rinieri
S&A Manufacturing (209) 394-8048 samfg.com
St. Helena Agricultural Services (707) 495-4157 sainthelenaag.com
Zenport Industries (888) 556-7756 zenportindustries.com
For more information about the suppliers listed above, visit winesandvines.com/buyersguide
or see Wines & Vines' 2018 Buyer's Guide.
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