Download - Grape Biology
GRAPE BIOLOGYRebecca 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, ‘cold-climate 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 vigor2) 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
Tertiary Bud
Secondary B
ud
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!