Understanding Vineyard Soils Flashcards
R.E. White (2009)
How many species of plant parasitic nematodes have been recorded on grapevines?
60
Name the four main species of Plant Parasitic Nematodes
Root-Knot
Root-Lesion
Dagger
Citrus
Which nematode is a vector for fan leaf virus? You need to know the Linnaean Taxonomy.
California Dagger Nematode or Xiphenema Index
What pre-planting fumigants can be used in vineyard soils for nematodes?
Furfural & Dichloropropene
Which soil type encourages nematodes the most?
Sand.
What are the four foundation species of rootstock?
Vitis Berlandieri
Vitis Rupestris
Vitis Riparis
Vitis Champinii
What are the three chemical tests for soil biological health?
- Soil Microbial Biomass
- Soil Organic Carbon
- Potentially Mineralizable Nitrogen
Do manures effectively combat soil acidification?
Yes.
What is Bio-Char?
Charcoal used as a soil amendment made from pyrolised biomass.
What would be the best cover crop in high vigour sites with high water availability?
Perennials such as Chickory for structural improvement and to maintain soil structure.
What cover crops are best for high winter rainfall and dry summer sites?
Winter annuals such as oats, barley or ryegrass that can be sown in summer and don’t compete for water during the growing season.
What are the four advantages of cover crops for soil texture?
Cover crops:
- Improve structure
- Help with the infiltration of water
- Improve soil strength
- Help with drainage
What are three chemical functions of soil organic matter?
Soil organic matter functions to:
- Cation exchange
- Soil pH
- Binding soil organic matter to soil minerals
What are three biological properties of soil organic matter?
Biologically, soil organic matter:
- Is an energy source
- Is a nutrient reservoir
- Assists with resistance of infection
What are three physical properties of soil organic matter?
Physically, soil organic matter:
- Helps with structure and stability
- Assists with water retention
- Acts as a thermal regulator
What is a bio-pesticide?
A naturally occurring bacterium or parasite that acts as an insecticide in a vineyard.
Name a specific bio-pesticide and describe it’s mechanism of action.
Bacillus Thuringiensis is a is a Gram-positive, soil-dwelling bacterium that occurs naturally in the gut of caterpillars of various types of moths and butterflies. During sporulation, many Bt strains produce crystal proteins called δ-endotoxins, that have insecticidal action on nematodes.
What is a brand name of a bio-inoculant?
Trich-a-Soil (Australia)
What are the three major constituents of bio-inoculants and what are their functions?
Gibberellins (GA’s): Regulate developmental processes including stem elongation and flowering.
Auxins: Phytohormones that dominate external stimulus response to light.
Cytokinins (CK): Hormones that promote cell division in roots and shoots.
What are the two advantages of micro-jets for irrigation?
- They deliver water a higher rate
- They better distribute water on sand, allowing cover crops in warm climates with sandy soils where drip irrigation would drain much faster with much less cover.
What are the 4 determining factors of irrigation method?
- Topography and soil type
- Availability and price of water
- Capital cost of installation
- Skill of vineyard staff
What are the 4 best practices of soil salinity management?
- Keep the leaching requirement as low as possible by using low-saline irrigation water.
- Use salt-tolerant rootstocks such as 1103Paulsen or Ramsey.
- Match the application of water to the vine demand using visual and ET data.
- Monitor drainage
What are two non-mechanical ways to improve soil drainage?
- Gypsum
2. Fibrous root grasses or deep tap root cover cropping.
What are three mechanical methods to improve soil drainage?
- Deep ripping
- Perforated PVC ‘aggi’ pipes
- Avoid compaction through eschewing machinery use.
Benefits of organic mulches mid-row?
They have low thermal conductivity and slow the transfer of heat in/out of the soil which means cooler daytime soils and warmer nighttime soils at high diurnal sites.
What is Albedo? Why does it matter?
Albedo: The measure of the diffuse reflection of solar radiation.
Mulches have higher albedo than bare soil, reflecting more light resulting in cooler soils.
What are four benefits of mulches, chips or cereal straw mid-row or undervine?
- Shading. Reducing soil water evaporatioon
- Supressing weeds. Use less herbicide.
- Rain drop splash prevention that helps to maintain soil structure.
- Encourages biological (worm) activity.
Why keep the mid-row mown during the growing season?
- Reduces evapotranspiration
- Improves yield by eliminating competition
- Reduces frost risk by allowing free movement of air.
What are three advantages of cover crops?
- Dries soil and controls vigour
- Improves soil strength and trafficability
- Protects from erosion and winter rains.
What is Abscisic Acid?
Abscisic Acid is a plant hormone with functions including the regulation of dormancy and stomatal closure. It is especially active in response to environmental stress such as hydric/heat stress.
What is the physiological plant response to partial root-zone drying?
Abscisic Acid from the roots tricks the plant into responding to false hydric stress, closing stomata and reducing water loss through the leaves.
Define Field Capacity
“Measure of the upper threshold of water available in the vineyard when gravitational seepage slows or stops.”
Define Aeration
– Pore space filled with water in the soil drains, leaving vacuous oxygen and nitrogen gas.
– Plant roots consume the gas and release carbon dioxide into the atmosphere.
– This exchange is aeration.
What are the three traditional methods of soil mapping?
- Aerial photography
- Auger samples
- Soil pits
What are the two types of igneous rock, their characteristics, and an example from the world of wine where they occur.
Acidic Igenous Rock (Granite Belt): Coarse and well-draining.
Basic Igneous Rock (Willamette Valley): Deep loams, finer texture and less free-draining.
What is sandstone?
Soil made of compressed sand, quartz, feldspar and rock.
What is dolomite?
A type of limestone that is especially magnesium rich.
Textbook definition of limestone.
“A sedimentary rock formed by calcium carbonate minerals or calcified skeletons of marine life deposited in ancient sea beds.”
Formula for Calcium Carbonate
CaCO3
What are the three types of soil profile?
Uniform, Gradiational and Duplex
What are the four basic ecosystem functions of soil?
- Nutrient Cycling
- Supporting biodiverity
- Storing and filtering water
- Maintaining resilience
What are the three key need-to-know points regarding phosphorus in vineyard soils?
- Inputs from the atmosphere are negligible
- Soils levels are rarely sufficient
- AMF helps tremendously
What are the three auxiliary should-know points regarding phosphorus in vineyard soils?
- Phosphorus fixation is complicated by iron and aluminium in the soil.
- It is more important at vineyard establishment than in a mature vineyard.
- Maintenance application is based on yield from the site, at about 600g removed from the soil for each tonne of fruit harvested.
What are the ideal YAN concentrations for fermentation?
250 - 350 mgN/L
What effect does low YAN have on ferment?
Sluggish and could stick, production of H2S from stress.
What effect does high YAN have on ferment?
Rapid, poor quality, high temperature.
What is the effect of nitrogen application after fruit set?
Ideal. Has a major effect on the berry nitrogen concentrations and trunk storage.
What is the nitrogen demand of the vine from version to harvest?
Bunches are main accumulators during this time, and mainly from nitrogen remobilised from within the vine.
When are the optimal times and methods to apply nitrogen fertilisers?
- Superficially after budburst
2. After flowering and before version by fertigation or soil drench.
What are the three naturally occurring sources of Nitrogen to vines?
- Legumes and cover crops - broad beans
- Atmospheric
- Ammonia (feces, urine and fertilisers)
What is the primary purpose of soil testing?
To determine the soils ability to supply an essential nutrient or assess toxicity - most notably salt.
What are five primary need-to-know points regarding Vinifera AMF?
- It is a self-regulating symbiotic relationship
- Because vinifera is perennial, the less effective strains dominate over time.
- Mid-row crops prone to AMF can help encourage diversity of strains
- Is is important for new vines especially in poor soil
- Mycorrhizal roots live longer
What is the function of a mycorrhiza?
The fungus enhances the uptake of otherwise immobile nutrients and in turn obtains organic material for growth.
What is a mycorrhiza?
A symbiotic association between a fungus and a plant root.
What study and when authoritatively considered distinctive old-vine wine characteristics?
Swinchatt and Howell (2004) used earth process units and hypothesised that the differential uptake of nutrients at bedrock weathering such as (Ca, Mg, Fe and Mn) might explain distinctive old-vine characteristics in wine.
Soil organic matte is confined to which area of a soil profile?
The A-Horizon (10-20cm)
The grapevine has evolved to explore ___________ soil volumes at ___________ root density.
The grapevine has evolved to explore large soil volumes at low root density.
What are two examples of elemental toxicity in world vineyards?
- High nickel concentrations in Calistoga in vines grown on serpentine rock.
- Copper concentrations with prolonged use of the Bordeaux mixture in Bordeaux.
What are the six micronutrients?
Iron (Fe) Managanese (Mn) Zinc (Zn) Copper (Cu) Boron (B) Molybdenum (Mb)
What are the ten macronutrients?
Carbon Hydrogen Oxygen Nitrogen Phosphorus Sulphur Calcium Magnesium Potassium Chlorine
Which three soil additions ought be introduced during ripping / pre-planting and what are their effects?
Rock Phosphate: Phosphorus support for essential functions.
Gypsum: for soil infrastructure and drainage
Lime: to adjust pH if necessary
What is the benefit of legume cover crops in pre-plantinga vineyard?
When plowed in, can stimulate beneficial soil organisms helping vines resist pests and disease in the planting stage. General overall soil health and biomass.
Chemicals used in soil fumigation
Furfural & Dichloropropene
What is the main issue with using reclaimed water for irrigation?
Often has a high nutrient load (toxicity) and salt concentrations.
What analyses are recommended for soil irrigation water?
pH, Ca/Mg (hardness) and Fe (clogs hoses)
How are the salt concentrations in irrigation water measured? What is the threshold?
Measured in decisiemens.
Threshold is
What is the most critical factor of water quality?
The concentration of dissolved salts.
How do you calculate peak demand for a drip irrigation system?
droppers/vine * L/hr * vph = L/ha/hr
What five factors determine the total water requirement for a site?
- Soil structure
- If overhead frost sprinklers are employed
- If there is an operational on-site winery
- Climate with specific reference to rainfall
- Likely peak demand
What five factors determine a sites likely peak water demand?
- Surface area
- Cultivar
- Density
- Yield Objectives
- Irrigation Method
Define Homoclime
Planting varieties in similar climates around the world based on similar continentality/HDD indices.
Define and state the equation for HDD (Amerine and Winkler)
- Based on the summation of ‘heat units’ for the 7 months of the growing season such that:
HDD = #days * (mean daily temp - 10)
Determining a new vineyard sites suitability starts with gathering as much data on which four factors?
- Climate
- Soil types and their distribution
- Availability of water
- Potential pest/disease risk
Beyond Phylloxera resistance and Nematodes, rootstocks offer other advantages, such as:
Salt/Drought Tolerance Tolerance of free lime Vigour Control/Vine Balance Water Use Efficiency Discrimination of nutrient uptake
There are _____ known genotypes of phylloxera with different degrees of lethality.
83
Define a “Cross”
offspring obtained through cross-pollination of two varieties of the same species (Ex: Ruby Cabernet, which s a cross between Cabernet Sauvignon and Carignon)
Define a “Hybrid”
offspring obtained through cross-pollination of two different species (Ex: Vidal is a hybrid of a non-vinifera and a vinifera species).
Short history of American Hybrids
Originally bred for harsh conditions and bred between vinifera, labrusca and aestevalis to produce cultivars such as norton, concord and delaware.
What are two successfully exported french hybrid varieties?
Chambourcin and Vidal
What is Muller-Thurgau?
A hybrid of Riesling and Madeline Royal created by Herman Muller in the Swiss Canton of Thurgau.
What pruning/training method has been noted for greater productivity with age?
Spur Pruned/Cordon Trained
What statement describes the relation of conductive tissue to mechanical support in Vitis Vinifera?
Because it’s a climbing plant, it has a relatively high proportion of ‘Conductive Tissue’ as opposed to ‘Mechanical Support’ tissue in the trunk.
What is the primary driving factor of bud burst and why is this a risk in some environments?
Once buds are in a state of enforced dormancy, it is TEMPERATURE that signals bud burst – therefore it may occur prematurely in the event of unseasonably warm temperatures.
How does soil temperature affect bud burst?
Bud burst date is positively correlated with soil temperature in the root zone.
How does frost risk correlate with variety chosen in site selection? Name an international example.
In frost prone sites, it is best to choose late bursting varieties in order to ameliorate frost risk early in the season. EX: Champagne will plant most of their Muenier on the most frost prone sites as it bursts later than Pinot Noir.
Which types of soil warm faster? Where are they located?
Well-drained or stony soils warm faster in spring than wet, clay soils and therefore such sites are preferred in cool climates such as Champagne and the Medoc and possibly to a lesser extent in Tasmania and Canada.
What is Cytokinin?
A plant growth hormone specifically tasked with root and shoot growth, apical dominance, bus burst and leaf senescence.
Does rootstock influence the growth cycle of the scion? How specifically at the time of bud burst, and cite examples.
May (1994) asserts that yes, and specifically the time bud burst and the length of time from bud burst to version and cane ripening.
University of Oregon: 110R (Richter) has the shortest time to ripening whereas 1103P (Paulsen) had the longest time to ripening.
How does water stress during the season affect bud burst in the following season?
If a vine is water stressed post harvest, it may lead to earlier bud burst the following season.
Speak to the findings of the Coombe 1964 Study on delaying bud burst.
Coombe (1964) asserted that delaying winter pruning until spring in frost or hail-prone regions by pruning to 2-node spurs and on account of apical dominance can delay bud burst by up to three weeks.
What is a growth regulating chemical that can be applied to delay bud burst?
Hydrogen Cyanamide (H2CN2) or Dormex can be applied 4-6 weeks before the normal time of bud burst.
Photosynthesis creates one sugar in the leaves:
Sucrose.
Sucrose is immediately hydrolysed in the grapes on account of the presence of acids to which two sugars?
Fructose and Glucose.
Which enzyme is responsible for the hydrolisation of Sucrose?
Invertase
What is invertase? Why is it important?
It is the enzyme that hydrolyses Sucrose into Glucose and Fructose.
What are some unfermentable sugars in wine and what property prevents them from being fermentable?
Arabinose, Hexose and Xylose - they are not six-carbon sugars, but rather have 3,4,5 & 7 carbon bonds.
Whereas sugars are produced photosynthetically in the leaves, where are acids produced?
Primarily in the grapes.
What are the two major acids in grapes?
Malic and Tartaric Acid
What is the process that decreases the level of magic acid in grapes as they mature?
Gluconeogenesis: ‘creating (genesis) new (neo) sugar (gluco)’ is a metabolic pathway where glucose is created from non-carbohydrate sources, in this case, Malic Acid.
Why are tartaric acid production and sugar accumulation positively correlated?
Tartaric acid is formed as a by-product of the synthesis of sugar, therefore, as sugar accumulates through ripening, so does tartaric acid.
What is flotation and what does it do?
Small bubbles of nitrogen are blown up through the must, catching solid particles and floating them to the surface where they are skimmed off.
What are some advantages of flotation clarification?
Increased speed of separation of the solids compared to the traditional sedimentation approach.
Ability to use it in either a continuous or batch mode.
Due to the dense nature of the solids on the surface, juice loss is minimised and the need for expensive juice recovery steps reduced.
R Lansing (2012) Wine Business Monthly: “you can go from pressing to fermentation in a few hours.”
What type of enzymes are necessary to assist in flotation clarification of juice musts?
Best to use a blend of pectolytic enzymes such as Rapidase Flotation.tm
What is the primary way to de-acidify wine?
Potassium bicarbonate.
Harvest date in relation to flowering?
The harvest date is largely determined by the length of time from bud burst to flowering.
Early to late flowering cultivars according to a study by Coombe 2004
Coombe (2004): Chardonnay Pinot Noir Malbec Grenache/Merlot/Riesling/Traminer Cabernet Franc Cabernet Sauvignon/Semillon/Syrah Barbera/Chenin Blanc Carignan
Are vines self-pollinating?
The commercial varieties of vitas vinifera are normally self-pollinated.
Are bees beneficial in the vineyard for pollination?
May (2004) found that there were reports of improved fruitiest and increase yields when bees were present in vineyards.
What is Couloure?
Poor fruit set from dropped stems as a result of a carbohydrate deficiency causing the vine to conserve resources that would otherwise be used for the development of grape berries.
What causes Couloure?
- Temperature at flowering
- Excessive soil nitrogen
- Overly vigorous rootstocks
- Pruning decisions that limit photosynthetic material
What varieties are more susceptible to couloure than others?
Malbec, merlot and grenache.
What is millerandage?
Grape bunches with berries at different stages of maturity as a result of bad weather at flowering or other nutritional, viral or environmental factors.
Is boron related to millerandage?
Yes. Boron is a micro-nutrient required for the synthesis of the growth hormone auxin and facilitate sugar transport.
What foliar spray is an option to combat millerandage?
Cyanamide (growth regulator)
“Is millerandage good for wine quality?”
- Evidence is anecdotal
- Mendoza Chardonnay is favoured by some winemakers (Kumeu River for example).
- May (2004) asserts that seedless berried have higher brim and higher anthocyanin concentrations, possibly resulting in more complex wines.
Major differences between Couloure and Millerandage according to Carbonneau et. al. (2007)
Millerandage is enviro-climatic and Couloure is Endogeny-Environmental.
What are five vineyard practices that can improve fruitiest?
- Tipping
- Topping
- Late Pruning
- Application of Growth Regulators
- Mineral Nutrition
What is ‘Tipping’ in relation to fruit set and flowering?
Removal of the apical 8cm of shoot at flowering to improve fruit set.
What is ‘Topping’ in relation to fruit set and flowering?
Removal of the apical 15+cm of shoot at flowering to improve fruit set.
What growth regulators can be used to improve fruit set, and what study confirmed their efficacy?
Cycocel. Chlormequat Chloride (CCC).
Collins and Dry (2009) found that the application of CCC as a foliar spray to Cabernet Sauvignon 1 week prior to flowering increased fruit set and yield by 60% on average.
How does mineral nutrition increase fruit set?
Foliar sprays of Molybdenum in Md deficient merlot in Australia increased yield as a function of improved fruit set. (Author unknown)
What is the major function of respiration in the vine?
Breaks down sugars and other carbon substrates to organic acids through glycolysis - these acids enter the citric acid cycle in the mitochondria and produce ATP.
What is the major factor regulating respiration?
Temperature. The rate of respiration doubles for every 10C increase in temperature and peaks at 30C.
What are the four primary factors that influence photosynthesis?
- Light Intensity
- Temperature
- Leaf Age
- Vine Water Status
What are the descending concentrations of components of a berry?
Water Sugars Acids Minerals Phenolic Compounds Nitrogen Compounds Volatile Aromas
What percentage of the berry is water?
70-80% by weight
Explain how sugars are precursors to volatile aroma compounds:
Glucose and Fructose contain other functional groups beyond hydroxyl; such as aldehydes and keytones:
These aldehydes and keytones are the starting point for the synths of phenolic and volatile aroma compounds.
What are the major constituents of TSS in grape juice and at what concentrations? What instrument measures this?
Sugars (90 - 94%) measured by a hydrometer.
1 degree Brix is how many grams sugar per 100 grams of solution?
1˚ Brix = 1g sugar per 100g of solution
1 degree Baume is how many grams sugar per 100 grams of solution?
1˚ Baume = 1.8g sugar per 100g solution
What is the formula for calculating Oeschle?
˚Oeschle = SG - 1. * 1000
What is specific gravity?
The measure of the weight of a solution compared t the weight of purified water.
1mL Solution Weight / 1mL Purified Water
What is the biochemical invitation of ripening?
The increased concentration of growth hormones such as Auxin, Ethylene and Abscisic Acid.
How can we predict wine alcohol level from juice ˚Baume?
As a loose guide, 1˚Baume = 1%ABV. Dependent on many factors.
Beyond Tartaric and Malic Acid, what are three other types of acid present in the berry?
Citric, Pyruvic and Succinic
Why are acids so important as a function of pH in wine?
They are sources of hydrogen and act to lower the pH of wine.
What are five essential functions of Acidity in Wine?
- Work to create an unfavourable environment for microbial spoilage
- Increase the action of SO2
- Enhance the action of clarification
- Increase the colour expression in red wines
- Provide beneficial conditions for ageing
What is the typical range of pH for grape juice?
2.6 - 4.3 depending on many factors.
What is the typical range of pH for wine?
3.0 -3.8 depending on many factors.
What causes the acidic taste of wine organoleptically?
It is related both to the free hydrogen ion concentration (pH) and the titratable acidity (TA) and needs to be balanced with other components in the wine.
What are four phenolic acids in wine?
- Benzoic
- Caffeic
- Coumaric
- Cinnamic
During winemaking what are two examples of phenolic acids released to create undesired effects?
- Cinnamic acids can be converted to browning agents enzymatically (polyphenol oxidase) which is the main cause of browning in apples.
- Coumaric acid can be decarboxylised by brettanomyces or dekkera to form 4EG or 4EP.
What are stilbenoids?
A class of plant poly phenolic compounds that are produced in the leaves and berry skins in response to fungal infection of tissue damage from wounds.
What is an example of a stilbenoid in grapes?
Resveratrol.
What are the three main Anthocyanins in grapes? Which is most present?
Cyanadin / Delphinidin / Malvidin
Malvidin is the most present.
Describe the study that used Anthocyanins to confirm vinifera species in France.
Ribereau-Gayon (1950’s) created the test to distinguish mono-glucoside anthocyanin from di-glucoside anthocyanin.
Mono-glucoside anthocyanin are only present in vinifera grapes, and di-glucosdie anthocyanin are present in other non-vinifera species.
What are flavonols?
A flavonoid compound that acts primarily in response to pathogens and environment stress.
What is a textbook example of a flavonol?
Quercetin.
What are flavanols?
Group of compounds found in red and white grapes that are responsible for the bitterness and astringent taste and texture phenomenon.
What are examples of flavanols?
Mainly catechins and epicatechins.
What is the relation of the development of flavanols to ripeness?
As ripeness increases, the concentration of flavanols decreases.
What is tannin?
A class of astringent poly phenolic molecules that bind to a precipitate protein.
Why are skin tannins less harsh than other seed/stem tannins?
They have a higher concentration of polysaccharide and protein complexes.
How would a lab measure tannin and anthocyanin content in wine?
High Performance Liquid Chromatography.
According to Keller (2010) why are white wines white?
A combination of chlorophyll, carotenoids and pale yellow flavonols.
Why are the concentrations of phenolic compounds in wine less than in berries?
Changes take place during time on skins and fermentation during winemaking such as oxidation, precipitation and polymerisation.
Name the 6 types of volatile aroma compounds in wine:
- Aldehydes
- Alcohols
- Esters
- Hydrocarbons
- Keytones
- Furans
Volatile aroma compounds exist as two forms:
Volatile and Perceptible
Precursor
Describe how precursors become volatile:
Many precursors are GLYCOSIDES.
GLYCOSIDES are molecules where a sugar is bound to ‘something else’ called an aglycone.
When the bond is broken between the sugar and aglycone, the volatile aroma is perceptible.
What are monoterpenes?
A large group of organic compounds produced by a variety of plants often with a strong odour.
Glycosides and Polyols are types of monoterpenes that are odourless. How to do they become detectable?
Hydrolysis
There are two styles of terpenes in grapes:
PVT: Potentially Volatile Terpenes
FVT: Free Volatile Terpenes
Cite the accumulation activity and concentration relationship of PVT and FVT according to Wilson 2004.
(Wilson, 2004)
Concentration in the berry is sometimes static for some terpenes whilst others increase dramatically post-veraison.
PVT exist in a 6-fold concentration to FVT.
What is the most detectible sesquiterpene in wine?
Rotundone
What are sesquiterpenes?
Where monoterpenes have 10 carbon atoms, sesquiterpenes have 15.
What are three sesquiterpenes found in wine.
Rotundone, Geosimin, Zingiberene
According to Siebert 2008/2011, what are the flavour development mechanics of rotenone in grape berries?
- Accumulates later in the berry ripening
- Only found in the skins
- Content was clone dependent
- Extracted during fermentation
What are norisoprenoids?
A diverse class of aromatic compounds that contribute to the varietal character in many wines, most specifically the aromatic varieties such as Riesling.
What is the general sensory threshold for norisoprenoids?
Generally low, around 2-10 nanograms per litre
What are the top three norisoprenoids in wine?
TDN, beta-damascenone, beta-ionone
What sensory contributions are attributed to TDN?
Petrol
What sensory contributions are attributed to beta/damascenone?
Fruit and flowers
What sensory contributions are attributed to beta-ionone
Sweet character and violets
What are methoxypyrazines?
“Important contributors to the distinctive herbaceous and vegetative characters of several grape varieties and their wines.”
What are the four main types of methoxypyrazines?
IBMP - Isobutyl Methoxypyrazine
SBMP - Secbutyl Methoxypyrazine
IPMP - Isopropyl Methoxypyrazine
EMP - Ethyl Methoxypyrazine
What part of the grape bunch has the highest concentration of Methoxypyrazines?
The stems (51%) followed by the skins (31%)
Why are methoxypyrazine levels higher in cool climate and cool vintage wines?
Because the accumulation of MP’s is related to ripeness through the synthesis of O-methyltransferase protein that is regulated by the VvHPMT gene that synthesises more at lower temperatures.
What can make a wine taste ‘salty…’
High levels of chlorine in the juice or wine.
What is the Field Capacity?
The amount of soil moisture or water content held in the soil after excess has drained away and downward movement has decreased.
What is the technical definition of Permanent Wilting Point?
The point at which the soil moisture is insufficient enough for plant tissue to regain turgidity.
What is sustained deficit irrigation?
Water supply to the vine is limited for the while of the growing season, typically regulated at 75% of optimal.
What are the 5 major points for regulated deficit irrigation?
- (WHAT) Restricts water to the vine for a specified period of time during the growing season. This is typically for a short period after fruit set.
- (WHEN) Specified period is typically fruitiest to veraison.
- (WHO) More often used for black varieties.
- (HOW) Careful and regular soil monitors and visual assessment of cine water stress are required for a successful implementation.
- (WHERE) Refill points and the amount of irrigation is matched to soil type, environmental conditions, yield and wine style.
What is PRD?
Partial Rootzone Drying mimics hydric stress response from the roots by releasing absicic acid to the xylem and affecting stomatal aperture.
What are three advantages of PRD?
Water Use Efficiency.
- Uses about 50% less water compared to fully irrigated vines
- Could potentially result in yield decrease, but the water savings are still considerable.
- Allows the vines to navigate severe weather and drought more evenly than SDI or RDI.
What are the three main disadvantages of PRD?
- Keeping the wet and dry zones properly established in slow draining soils
- The timing of the cycle needs to be accurate for soil type and weather.
- The system performs best in free draining soils.
Chaves et. al 2010 // Collins et al 2010
What are two principle methods for limiting water availability to vine roots?
- Cover crops such as chicory, lucerne and ryegrass, although they may have a negative competitive effect if chosen for the wrong site.
- Root pruning seasonally.
________ & _________ in (1234) discuss seven ways to conserve water in the vineyard:
Profit and Ward (2009)
- Slashing and mowing cover crops in early spring
- Applying underline mulch
- Construct catchment areas in the vineyard
- Plastic sheeting mid-row for water harvesting
- Moisture monitoring to minimise wasteful irrigation
- Watching scion and rootstock to soil type
- Reducing evaporative loss by covering storage dams.
What are 3 advantages of mulches.
- Can increase organic carbon content.
- Encourage earthworm activity
- Reduces evaporative moisture loss
_____________ (1234) made this claim in regards to water savings potential of mulches.
Buckerfield (2001) “10-30% water savings is possible from applying mulch in sufficient quantities.”
________ & ________ (1234) made this statement regarding the positive effects of mulch in a vineyard in New Zealand.
Mundy & Agnew (2002)
“Application of mulch:
- Increased soil moisture retention,
- Increased Soil phosphorous levels
- Increased total number of desirable soil fungi
- Increased juice nitrogen concentration and
- Improved vine health
in a vineyard in New Zealand.”
What are the three kinds of sulphur compounds found in wine?
- Elemental Sulphur (S) used as foliar sprays in the vineyard to protect vines from botrytis and mould.
- Sulphur Dioxide (SO2) which is used as an antioxidant and antiseptic in winemaking
- Hydrogen Sulphide (H2S) which is a yeast artefact of fermentation that creates off flavours.
What is the main cause of soil salinity?
The application of saline irrigation water.
How to own rooted vines perform in saline soils as opposed to rootstocks? What are the most salt tolerant rootstocks?
Own rooted vines tend to be less salt tolerant than those on rootstock. Ramsey is a very salt tolerant rootstock.
What are the 5 ways to decrease soil salinity.
- Use irrigation water low in dissolved salts
- Reverse osmosis your irrigation water
- Promote the leaching of salt through winter rainfall
- Blend low and high saline irrigation water to create a balance that is below critical threshold.
- Use salt tolerant rootstock such as Ramsey.
Research by ________ in (1234) suggested what relationship between rootstock and scion.
Zhang (2002) Michigan State University.
Interactions between rootstock and scion also affect the salinity levels in vines.
How can rootstock choice affect salinity in the vine?
Some rootstocks like Ramsey and 1103 Paulsen accumulated less salt than when on own roots in a range of salinity experiments.
Can salty soils result in salty wines?
Yes.
Walker et. al (2002) state that high soil salinity or the use of high saline water can result in increased NaCl in the berries and wines, and in some cases the reins can taste salty.
How do you calculate Water Use Efficiency?
WUEy = Y/I = t/ML
Where the weight of the fruit removed at harvest (y) is divided by the amount of water incident on the vines (I).
Expressed as megaliters/ton
Why would a viticulturist want to remove leaves in bunch zone?
- Improve berry concentration and composition
- Reduce disease risk
- Improve spray penetration/effectiveness
