GRAPE BIOLOGY
Rebecca Harbut
Dept of Horticulture, UW-Madison
VITACEAE
• Mostly woody, tree-climbing vines
• Tendrils and inflorescences opposite the
leaves
• 12 genera within the family
– Vitis
– Ampelocissus
– Clematicissus
– Parthenocissus (Virginia Creeper)
– Ampelopsis
– Cissus (Kangaroo vine)
GENUS VITIS
• 60 species of grape
– 30 species native to North America
• Two subgenera:
– Euvitis (38 chromosomes)
• Grapes adhere to cluster
– Muscadinia (40 chromosomes)
• Grapes fall off cluster as they mature
GENUS VITIS
• Euvitis
– Vitis vinifera
European wine grapes
» Over 5000 cultivars
» 90% of world grape production
– Vitis labrusca American species, fox grape
– Vitis riparia
American species, ‘coldclimate grapes
• French-American hybrids
– ‘Marechal Foch', ‘Vidal Blanc', ‘Chambourcin', and ‘Seyval'.
• Muscadinia
– Vitis rotundifolia
Muscadine grapes (grown in
SE USA, lack cold hardiness
EUROPEAN VS. AMERICAN
Vitis Vinifera
• Cold tender
• More upright growth
• Phloxera susceptible
Vitis Labrusca &
Vitis Riparia
• More cold hardy
• More trailing growth
• More vigorous growth
GRAPE USE IN U.S.
Wine - 50-55%
Raisins - 25-30%
Table - 10-15%
Juice, jelly, etc. - 6-9%
Canned - < 1%
GRAPE ANATOMY
ROOTS
• Grapes have tap root system
– Main tap root with lateral roots
• Most absorption (nutrients and water)
carried out by root tips and root hairs
– Soil conditions are critical (proper soil test
and site prep)
• Vesicular arbuscular mycorrhizae
(VAM)
– Most associated with plants in low P soils
– Most grapes have VAM infecting roots
ROOTSTOCKS
• Primary reason - Phylloxera resistance
• 3 species used:
1) Vitis rupestris: A native of the eastern
United States which provides vigor
2) Vitis berlandieri: A native of the dry
southwestern United States which
provides drought tolerance.
3) Vitis riperia: A native of the
northeastern United States which
provides cool weather tolerance.
Photo: OSU
OWN ROOTED VS. ROOTSTOCKS
• Grafted vines can be more expensive
– Increased time in nursery
– More labor
• Own rooted can be better in areas prone
to winter damage as new growth can
come from established roots
• Rootstocks can be used to compensate for
less than ideal sites
ROOT GROWTH AND IRRIGATION
• Root growth is critical for vine
establishment
• Irrigation during can allow for improved
root establishment
• Deep watering encourages roots to move
down into the soil profile
TRUNK
• Primary support structure
• Important in carbohydrate storage
• May be single or split
CANES, CORDONS AND SHOOTS…
OH MY!
• Cordon-permanent stem
– Trained horizontally
– Not all systems have cordons
• Cane
– One year old shoot
– SPUR- Canes pruned to 2-3 buds
• Shoot
– Current seasons growth
– Bear fruit clusters
One year old cane
Shoot
Cluster
Tendril
BUDS INITIATION
• Primordia- undefined tissue with potential to
develop into a defined structure
• Primordia can become: tendril, shoot,
inflorescence
– Temperature, vine vigor, light affect cluster size
and number
• Primordia initiate when only few inches from
growing shoot tip
BUDS DIFFERENTIATION
• Differentiation- process in which primordia
become committed to develop into a
specialized tissue
– Tendril, inflorescence, shoot
• Secondary buds differentiate later
– Important if primary bud is killed
Primary Bud
Secondary Bud
Tertiary Bud
TENDRILS
• Specialized lateral branches
– Derived from same undifferentiated primordia as
flowers
•
•
•
•
Grow away from the light
Become lignified
Allow plant to invest less in structural trunk
If tendril does not latch onto anything it will
wither and die
• Tendrils have determinate growth
FLOWERS
• Small 1/8 inch, indiscrete
• 5 sepals, petals, stamens
• Superior ovary
– 2 locules/2 ovules per locule
• Cultivated grapes have perfect flowers
– Some wild have male and female flowers
– Evidence that cross pollination increases size
Fused petals = calyptra
INFLORESCENCE/CLUSTER
• Panicle inflorescence
– Inflorescence usually
on 3rd or higher node
– # of inflorescence
(clusters)/shoot varies
by:
• Management, cultivar,
environment
• 0 to 5 (or more)
HARDINESS
• Vinifera


0 to -10°F bud injury
<-10°F trunk injury
• French hybrids


-10°F bud and trunk injury
-20°F kill buds and trunks
• American types

-20°F would cause crop reduction
FLOWERING
• Grapes flower long after bud-break
• Shoot must develop enough leaves to
support fruit development
• Flowers open when shoots have 15-17
nodes
• Length of flowering period dependent on
environment
POLLINATION
• Wind pollinated
– Weather dependent
• Fertilization dependant on weather
– Pollen tube must grow down through style
(highly temperature dependent)
– Cool weather during fertilization decreases
fruit set
FRUIT SET
• Fruit Set- percent of flower buds that develop
fruit
• Auxins (hormone) are released from pollen
tube which stimulates growth of ovarian
tissue
• Factors affecting fruit set:
–
–
–
–
–
Temperature
Light (photosynthesis)
Stored carbohydrates
Water
Nutrients ~ primarily Zn and B
FRUIT
• Grapes are true berries
– primary tissue from ovarian tissues
• Berry size influenced presence or absence of
seeds and then seed mass
– V. vinifera- 1-2 seeds
– V. lubrusca >2 seeds
• Seedless grapes
– Most not really seedless (stenospermocarpic)
– Seeds form, but abort
– Still enough hormone production to stimulate large
berry growth
– Truly seedless (parthenocarpic) have smaller berries
BERRY COMPOSITION
• 75-85% water
• 15-25% sugar
• 0.5-1.0% organic acids (malic, tartaric,
citric)
• 0.25% pectin
• Secondary metabolites
BERRY COMPOSITION:
SECONDARY METABOLITES
• Components that make grapes distinctive
• Not essential for survival of the plant
• Thousands have been identified, likely
many more
– Phenolics, anthocyanins, flavenoids
• Synthesis is genetically controlled
• Influenced by:
– Environment, plant age
Phase I
Phase II
Phase III
BERRY DEVELOPMENT:
PHASE I (0-40 DAF)
• Phase I- cell division and expansion
– 17 cells to 200,000 (600,000 cells at veraison)
– No carbohydrate accumulation
– Accumulation of tartaric and malic acid
– Duration is similar for most cultivars
– Berries are green due to cholorophyll
BERRY DEVELOPMENT:
PHASE II (40-60 DAF)
• Phase II-lag phase
– Slowest phase of development
– Berries are firm
– Berries begin to loose chlorophyll
– Organic acids accumulation peaks
BERRY DEVELOPMENT:
PHASE III (60-120 DAF)
• Phase III- Fruit softening (véraison)
– Rapid berry growth (cell enlargement)
– Initiation of ripening
– Chlorophyll breaks down
– Anthocyanins accumulate in skin (red grapes)
– Sugars accumulate
– Organic acids decline
– Secondary metabolites accumulate
Cabernet Sauvignon
Flame
Sauvignon blanc
PROPAGATION
•
•
•
•
Cuttings root easily
Cut canes with three nodes (bud)
Can also tip layer
Be careful about propagating your own
material
– Royalties, quality, identity
SUMMARY
• Spend the time to understand the critical
growth periods of the grape
• Grapes are one of the most complex crops
to grow
• Before you grow it, be sure you know it!