Category Archives: Cabernet Sauvignon

Sep 06 NO comments
aroma, Cabernet Franc, Cabernet Sauvignon, enology, entertainment, flavor, france, fun, grapes, History, Merlot, odor, Origins, plants, Viticulture, Whos Your Daddy, wine

Who’s Your Daddy?: Merlot



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The “Who’s Your Daddy” series takes a brief look at the parentage of grapes, in order to get a better understanding of where particular varietals come from and how they are genetically related to one another.  So far, we’ve covered: Cabernet Sauvignon, Syrah, Chardonnay, Petit Verdot, Sangiovese, Nebbiolo, Pinotage, Gamay, and Petite Sirah.  Feel free to click on any one of the varietal names to read all about their parentage.

The subject of today’s “Who’s Your Daddy” post is Merlot, which along with Cabernet Sauvignon is one of the most popular varietals in the world.

History

In relative terms, the Merlot grape has not been around very long.  Some sources indicate that the first mention of Merlot came from an official in the Bordeaux region of France in 1784, though others say it wasn’t until the 19th century that Merlot had been noted in the record books.  It has been said that this official declared Merlot some of the finest wine of its time.  Today, Merlot remains one of the five major Bordeaux varietals, and has also seen widespread plantings throughout the world, including in the United States, Chile, Australia, and many others.

In the 1950s, a severe freeze had all but wiped out the Merlot (and Malbec) grape vines in France.  French winegrowers attempted to replant the vines the next year; however those vines were subsequently destroyed by rot.  Year after year, attempts to replant the Merlot were made, only to be met with year after year of failure and ruin.  As a result of the physical and financial loss occurring year after year, the French government placed a ban on planting new Merlot vines in 1970, which was later lifted in 1975 due to increasing popularity of Merlot wines worldwide.

Rather than me telling you about the most recent history of Merlot, including its’ “death” and then it’s more recent comeback, I’ll leave it up to the clever folks at Gundlach Bundschu with this clever video:

Viticulture

Merlot is characterized by having loss grape clusters and large berries.  The name Merlot; likely derived from the word Merle which means “blackbird” in French; is likely a reference to the dark color of the grapes (or perhaps to the fact that blackbirds are known to be very fond of the juicy berries).  The Merlot grapes are a dark bluish color, and also possess relatively thin skins, which contributes to the relative softness of the wine.

Merlot grapes tend to be less hardy than other varieties, which results in greater risk of infection by molds, mildews, or rots.  While it is more able to thrive in cooler climates than Cabernet Sauvignon, it still prefers to grow in a warmer growing environment.

Merlot does best when grown in clay or limestone soils, and ripens earlier than its’ Bordeaux cousin, Cabernet Sauvignon (2 weeks earlier, roughly).  At harvest, Merlot produces higher alcohol and lower acidity than other Bordeaux varieties.  These characteristics allow Merlot to calm the stronger tannins and structure of other Bordeaux varieties such as Cabernet Sauvignon, which allows it to function as a nice blending grape for that region.  Of course, Merlot is also well known and able to function as a single varietal wine as well, though in the Bordeaux region of France and in regions where it is more difficult to grow, it is known primarily to be blended with other varietals.

Sensory Characteristics

In general, Merlot tends to be softer and fruitier than its cousin, Cabernet Sauvignon, though it does share some similar aromas and flavors.  Of course, every bottle of Merlot is going to taste slightly different, depending upon where it was grown, what vineyard management practices were employed, and what winemaking techniques were used, though there are in general some common tones that resonate throughout the Merlot world.  Some of these common aromas and flavors of Merlot are black cherry, currant, and cedar, as well as tobacco, licorice, and chocolate.  Other aromas and flavors found in Merlot wines include black raspberries and plums, as well as jam and blueberries.

So, Merlot….”Who’s your daddy?”…

Enough of this chatter about the history, viticulture, and sensory characteristics of Merlot.  Let’s get down and dirty…Who’s your daddy, Merlot?

In 2009, a group of researchers at the University of California at Davis cleared up some of the fog surrounding the Merlot parentage debate.  Using inheritance analysis of DNA markers from thousands of grape varieties, the group was able to confidently answer the question of which grapes the Merlot grape originated from.

Without further ado, I present to you the parents of Merlot:

http://www.hort.cornell.edu/reisch/grapegenetics/
Varietyphotos/cabernetfranc.large.jpg
Cabernet Franc…….



……and……
http://lescepages.free.fr/
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……Magdeleine Noire des Charentes






There you have it!  This research also found several other relatives of Merlot, including Carmenére, which may be a sort of sibling of Merlot.

If you’d like to learn about the parentage of another grape variety, simply leave a comment below and I’ll see what I can dig up!  Note: there are many grape varieties with unknown parentage still, but I’ll try my best to find data that may suggest particular relationships and origins.  This type of genetic research is ongoing, so even if I can’t find information on a particular grape of your choosing today, that may change in the future!

Cheers!
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Aug 29 NO comments
agriculture, anthocyanins, Australia, Cabernet Sauvignon, ecology, economics, enology, fermentation, GPS, grapes, phenolics, prices, remote sensing, research, soil, Viticulture, wine chemistry, wine quality

Selective Harvesting: Is It Right For Everyone?



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When it comes to selective harvesting methods in the vineyard, there is an assumption that these methods may not be economically feasible for large quantity-producing wineries, as selective harvesting almost always requires more time, effort, and man-hours in executing.  Past research has found that the yield and quality of grapes is highly variable in the vineyard, which gives opportunity for winegrowers to better manage their resources and harvest practices for the desired quality of wine produced.

What is “Selective Harvesting”?

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Selective harvesting is defined as the split picking of fruit according to their yield and quality, in order to monopolize on a specific quality level in the grapes, and ultimately, finished wine.  This is sometimes achieved by sorting the grapes in the field into different bins depending on quality criteria, or by harvesting different sections of the vineyard at different times, again depending on quality criteria.  Studies have shown that grapes harvested from different portions of a vineyard may have significant chemical or sensory characteristics, which are often due to variations in the land and soil underneath the vineyard.

Selective harvesting may be problematic at times, as sometimes a winery may only have access to a single crusher or a minimum tank size of 75 tons, which can make separating grapes into two bins at harvest an issue, as well as filling a single tank with enough juice from a smaller selective harvest.  One study demonstrated that a 3 hectare low-yielding vineyard could not produce enough grapes to fill a fermentation tank with juice, which may make selective harvesting of smaller areas difficult when only certain sized tanks are available for use.

Perceptions of Selective Harvesting in Australia

In general, Australian wineries have the view that selective harvesting is only appropriate for small boutique wineries, or very large wineries that have access to a wide variety of equipment.  Those wineries in Australia’s inland warm irrigated region, according to the authors of the study presented to you today, are under the assumption that selective harvesting is not within reach.  It is because of this assumption that Bramley et al, 2011 sought to examine this assumption more closely, and to either support or refute the idea using field experimentation and economic analysis.

How did they do it?

The vineyard for this study was a Cabernet Sauvignon vineyard, planted in 1994, and located at the Deakin Estate in the Murray Valley of northwest Victoria, Australia.  Plant vigor and grape yield was calculated using remotely sensed digital multispectral video imagery, as well by using mechanical harvesters with GPS and Farmscan equipment.  Zones within the vineyard were characterized by being either high-yielding or low-yielding based on information gathered by the aforementioned methods.  After determining the yield would be too low for the fermentation tanks at the low-yield site, another low-yield site (harboring grapes with very similar characteristics as the grapes from the original low-yield site) from a Cabernet Sauvignon vineyard at Deakin Estate was also included in order to obtain the minimum yield necessary to fill the fermentation tanks available.

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Grapes were monitored throughout the growing season, and were harvested at 24 oBrix.  12 random bunches were collected from each zone in order to measure bunch weight, mean berry weight, juice Brix, pH, titratable acidity, anthocyanins (color), and phenolics.  Wines were created from bow low-yield zones and the high-yield zones in small-lot winemaking methods and also at the commercial scale.  For small-lot winemaking, 200kg of grapes were harvested then subsampled into three 50kg batches, and malolactic fermentation was not allowed to occur.  Commerical wines were made in 75 ton fermentation tanks which were filled for high-yield zone wines and filled only to 51 tons for the low-yield zone wines.  Malolactic fermentation was allowed to proceed for the commercial wines.  Standard winemaking procedures were used for all wines.

Experimental wines underwent a sensory analysis by 25 untrained panelists and Compusense Five (a sensory software tool).  For each comparison, the first sample presented was the reference sample, which was followed by two other samples, one of which was the same as the reference sample.  Panelists were asked to smell and taste the samples and to identify which sample was the same as the reference sample and were asked to provide the reason for their choice.

What did they find?

  • First and foremost, the authors noted a strong similarity between the remotely sensed data and the data collected from the GPS located on the harvesting machinery.  This provides evidence that the zones were actually separated properly into low-yield and high-yield zones. 


  • Wines created from the low-yield zone and wines created from a mix of low-yield zones were not significantly different, indicating that it was appropriate to mix the two low-yield sites without lowering the overall quality of the wine.


  • The wines from the high-yield zone tended to be more acidic and astringent than the wines from the low-yield zone.



  • When wines were made commercially, there was a significant different between wines made from high-yield zone grapes and wines made from low-yield zone grapes.  The low-yield zone grapes tended to be fuller bodied and less astringent, and with a fruitier aroma than the high-yield zone grapes.


  • Bunches from the high-yield zone were larger than those from the low-yield zone.  However, anthocyanin and phenolic concentrations were higher in wines made from low-yield zone grapes compared with high-yield zone grapes.  This result suggests greater wine quality in low-yield zone wines.


What do these results mean?

First, the results show that there are significant differences in yield and grape quality throughout different sections of a vineyard, which supports the need for purposeful zone delineation via posts, wires, or other means to separating sections of the vineyard.  Taking this one step further, another important result from the study is that if using remotely sensed data, it should be confirmed via ground-truthing (i.e. collecting information on the ground) to be certain the vineyard is being properly delineated.

The authors note that selective harvesting gives the winemaker greater control over the final blend of the wine, and ultimately the overall quality.  What many Australian winemakers are concerned about is the overall effect of cost when implementing such a strategy.  Even after taking in the harvest cost, the cost of small-lot winemaking, the harvest cost related to differing yield sizes, and total retail values (less expensive versus high-end prices), the researchers found that there was a total net benefit to a selective harvesting strategy.  See the table below (Table 2 from Bramley et al, 2011) for exact costs and benefits calculated.
Table 2 from Bramley et al, 2011

What about those vineyards that don’t make wine themselves?

There are many vineyards in Australia (and other places of the world, for that matter) that grow grapes to sell to other wineries, and not to make wine themselves.  Thereby, they do not have the added revenue of wine sold to add into the cost-benefit equation.  The authors were well aware of this fact, and performed a similar economic analysis to the one just mentioned, except leaving out the cost of winemaking and any potential wine revenue.  Even after taking these things into consideration, the researchers found that selective harvesting results in an increase in net financial benefit by more than 9% (in this particular example).  See the table below (Table 3 from Bramley et al, 2011) for exact costs and benefits calculated.

Table 3 from Bramley et al, 2011

Conclusions

The results of this study indicate that the notion that selective harvesting is only feasible for larger wineries with a variety of equipment sizes or small boutique wineries is incorrect, and that selecting harvesting may be financially feasible and beneficial for those wineries who undertake more large-scale production methods (at least in warm inland irrigated regions of Australia).  It is important to note that in order to maximize the benefit of selective harvesting, detailed analysis of the vineyard to delineate yield and quality zones must be confirmed using both remote sensing data and data collected directly from the ground.

Overall, I found this study interesting in that it showed that selective harvesting may be an option for all types of wineries, and is not limited to only those wineries with a greater variety of equipment or small boutique wineries.  One needs to remember, however, that this study occurred in a very specific wine region (warm inland irrigated region of Australia), the results of which may or may not be extrapolated to all wine regions around the world.  More research would need to be done to determine if this sort of harvest method is appropriate for wineries in any given wine region.

What do you all think of this topic?  If you’re curious to know more details about the methods or results of the study, please feel free to ask and I’ll see what I can find!

Please feel free to leave your comments below!

Reference:

Bramley, R.G.V., Ouzman, J., and Thornton, C. 2011. Selective harvesting is a feasible and profitable strategy even when grape and wine production is geared toward large fermentation volumes. Australian Journal of Grape and Wine Research 17: 298-305.

DOI: 10.1111/j.1755-0238.2011.00151.x
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 27 NO comments
agriculture, Cabernet Sauvignon, Chardonnay, ecology, environment, grapes, powdery mildew, research, Viticulture

Different Vineyard Training Systems Alter Susceptibility of Grapes to Powdery Mildew



One of the most common pests to vineyards all over the globe is powdery mildew (Erysiphe necator Schwein).  It is responsible for causing widespread destruction in nearly every viticultural area worldwide, and is a fungus that is able to develop in a variety of temperatures and humidity levels.  Though it is present in nearly every corner of the globe, the severity of the infection from vineyard to vineyard is dependent upon a variety of factors, including the variety of grape, the vigor of the vines, the type of protective chemicals applied, and the weather conditions.

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Some studies have found that the training system used in the vineyard has a significant effect on powdery mildew development, by altering the microclimate in the cluster area.  It appears as though light intensity and UV radiation appear to contribute to the changes in powdery mildew development severity, both of which have also been shown to affect the chemical composition of the grapes themselves.   Specifically, work done by the authors of the paper presented today found that there were significantly lower powdery mildew infections in grapes trained in the free canopy system versus grapes trained in the vertical shoot positioned system.

The article presented today is a very short article with the objective of investigating whether or not the difference in infection incidences as described above were due to light intensity itself, the susceptibility of the berries, or both.

Methods

The study was performed in June 2003 at an experimental vineyard in the Golan Region of Northern Israel.  Grapevines planted in this vineyard were Cabernet Sauvignon and Chardonnay (both with good susceptibility to powdery mildew).

Half of the vineyard was subject to a vertical positioned system, while the other half was left as a free canopy, though topped to one meter in length after fruit set and hedged no more than twice during the growing season.  Dates of bud burst, flowering, and fruit set were the same for both training systems.
Figure 1 from Zahavi and Reuveni, 2012

Experiment 1: Clusters were picked when the diameter of the berries were 3-5mm.  Thirty to forty berries from each training system were selected and placed in plastic boxes.  Berries were then inoculated with powdery mildew.  Twenty more berries were placed in plastic boxes but not inoculated with the fungus to serve as a control to monitor natural infections from the field.  Percent of infected berries was then calculated 7-9 days after inoculation with powdery mildew.

Experiment 2:  Clusters were inoculated in the exact same manner as in Experiment 1, however, 1-2 hours after inoculation, berries were returned to the vineyard and either placed on the cluster zone/vine cordon of their original training system or on vine cordon of the opposite training system for 8 hours.  After this time, berries were brought back to the laboratory and disease development was monitored 7-9 days after.

Results

  • For the first experiment, incidence of powdery mildew was significantly higher on berries originating from the vertical positioned vines than those originating from the free canopy system.
  •  For the second experiment, berries that originated from the vertical positioned vines and then incubated in those same vines were significantly more infected with powdery mildew than those berries that originated from the free canopy vines and incubated in either of the vine position systems.
  • Also in the second experiment, berries that originated from the vertical positioned vines that were incubated in the free canopy system vines had an intermediate level of powdery mildew disease severity.
  • Powdery mildew did not develop on control berries that were not inoculated.


Conclusions

The results of this study found that grapes originating from a free canopy system, which has a greater exposure to light, resulted in lower susceptibility to powdery mildew infection than grapes originating from vertically positioned vines, which have a denser canopy that does not allow in as much light. 

By transferring inoculated free canopy grapes into a vertical positioned set up, powdery mildew development decreased as a result of a pre-conditioning effect on the grapes.  In other words, this means that the grapes were less susceptible to infection after being exposed to higher intensity of light from the free canopy system.  The authors conclude by stating that the conditions in which grapes develop influence the severity of infection by powdery mildew.

Being a short experiment, there are certainly many more questions that these results raised which cannot be answered with the results found.  For example, how do the different training systems affect the chemical and sensory characteristics of the wine?  Are there any differences?  Since it appears grapes grown under a vertical positioned system are more susceptible to powdery mildew than grapes grown under a free canopy system, it suggests that perhaps there are some chemical defense changes within the plant, which may or may not affect the overall sensory characteristics of a wine made from those grapes.

Would the results be the same for each and every variety of grape out there?  Or are Cabernet Sauvignon and Chardonnay more susceptible to powdery mildew invasion under a vertical positioned system while say Riesling and Malbec are more susceptible under a different training system?  I would think it once again boils down to plant defensive chemistry, but we’d need some further studies examining many more grape varieties to be sure.

What about other training systems?  What is the “hierarchy of susceptibility” for powdery mildew in Vitis vinifera grapes? 

The results of this study are not to suggest that one should switch from a vertical positioned system to a free canopy, however without any extra chemical defense (fungicides, etc), it might be recommended that one reconsider the training system that is employed at one’s vineyard.  There are, of course, many other factors that any given training system will affect, thereby requiring one to weigh all the pros and cons before choosing any particular method.

I’d love to hear what you all think of this study!  What questions did this study raise for you?  Please feel free to comment below!

Source: Zahavi, T., and Reuveni, M. 2012. Effect of grapevine training systems on susceptibility of berries to infection by Erysiphe necator. European Journal of Plant Pathology 133: 511-515.

DOI: 10.1007/s10658-012-9938-z





I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 04 NO comments
anthocyanins, aroma, Cabernet Sauvignon, china, ecology, enology, environment, flavor, phenolics, resveratrol, wine, wine chemistry, wine quality

The Phenolic Composition of Cabernet Sauvignon Wines in China: Demonstrating Terroir Effects



Phenolic compounds, which are found in grapes, can significantly influence the aroma, flavor, mouthfeel, color, and overall quality of a wine.  These compounds are found naturally in grapes, however can also be synthesized throughout the fermentation and aging processes.  As a result of this, there are many factors that can influence the phenolic composition of a wine, including but not limited to; grape variety, environmental influences, and winemaking techniques.  For wines that are single variety based and not aged after fermentation, the phenolic composition of the wine is highly dependent upon the grape and the conditions in the vineyard. 

Specifically, this is what the term “terroir” embodies: it is the definition of the geographical and environmental origin of the grapes that include characteristics such as soil type, climate, and topography, and who all those things combine to affect the composition and quality of a wine.  Favorable terroir conditions can produce very high quality grapes, which is a critical starting point for a good wine.  By understanding how terroir affects the phenolic composition of grapes, vineyards managers or winegrowers will have a greater understanding of how to manage and maintain the grapevine that will produce high quality wines.

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There is a lot known about terroir effects on grapes and wine throughout many portions of the world, however, there is little known that specifically compares individual phenolic compounds of single varietal wines from different winemaking regions, and even less so known about these effects in the newer wine regions of China.

The wine regions of China are very ecologically diverse, considering they are spread all over the vast country.  The Yunnan Zone can be found at altitudes between 1900 and 2400m above sea level; the Gansu Qilian Zone is located next to a desert; the Ningxia Helan Zone is past the mountains; the Yantai Shandong Zone and Changli Hebei Zone are by the sea; and finally the Huailai Hebei Zone is located in a cooler climate.  It is because of these regional differences that there is great potential for regional terroir effects in wines produced from Chinese grapes. 

The goal of the study presented today was to analyze the differences in phenolic composition in Cabernet Sauvignon vines from different winegrowing regions in China.

Methods

 5 growing regions in China were studied: Deqin of Yunnan (YNDQ); Yuquanying of Ningxia (NXYQY); Yuma of Ningxia (NXYM); Qilian of Gansu (GSQL); Changli of Hebei (HBCL); and Yantai of Shandong (SDYT). 

Cabernet Sauvignon vines were studied, since they are easily found growing in all wine regions of China.  Grapes were harvested at their full-ripened state and were in strict accordance with local wine production technical rules.  Wines went through alcohol and malolactic fermentations, but did not age afterward. 

In each growing region, two to four wineries were chosen and about 1000mLof fresh wine from each winery was collected from at least two different fermentation processes.  To ensure only regional terroir characteristics were at play, all wines from each growing region were pooled.  Each wine sample was studied in triplicate.

Anthocyanin phenolics were analyzed, as well as non-anthocyanins including flavan-3-ols, flavonols, hydroxybenzoic acids, hydroxycinnamic acids, and stilbenes.  Anthocyanins were quantified by using malvidin-3-O-glucoside as a standard, and flavanols, flavonols, hydroxybenzoic acids, hydroxycinnamic acids and stilebenes were quantified by using catechin, quercetin, gallic acid, caffeic acid, and resveratrol, respectively.

Results

Anthocyanins

  • 24 anthocyanins were identified in Chinese Cabernet Sauvignon wines.

o   All 24 were found in each Chinese growing region studied.
  •  Wine from the YNDQ region had the highest levels of anthocyanins.
  • Wines from GSQL and NXYQY regions had significantly lower levels of anthocyanins (due to very low delphinidin derivatives).
  • Cyanidin-3-O-glucoside and peonidin-3-O-glucoside were 5 times higher in YNDQ wines than wines from any other region.
  • Wines from HBCL had the highest levels of malvidin-3-O-glucoside and malvindin-3-O-(6-O-acetyl)-glucoside.
  • There were significant differences in anthocyanin levels between wine regions in China.


Flavan-3-ols

  • 16 flavan-3-ols were found in wines from all Chinese growing regions studied.
  • SDYT region displayed the highest levels of flavan-3-ols.

o   Concentrations in this region were nearly double that of GSQL and YNDQ wines.
o   This region also showed the highest levels of gallocatechin and procyanidin dimers.
  •  Wines from GSQL and YNDQ had the lowest levels of total flavan-3-ols.
  • NXYM wines had the highest levels of epicatechin.

o   These levels were nearly 30 times greater than levels found in YNDQ wines.
  • The highest levels of catechin were found in YNDQ wines.
  • SDYT wines had the lowest levels of catechin.


Flavonols

  • 10 flavonols were found in Chinese wines from the growing regions of study.
  • Highest levels of flavonols were found in YNDQ wines.

o   These levels were nearly 4 times greater than levels found in GSQL wines.
  • YNDQ wines had much higher levels of quercetin derivatives than wines made from other wine regions in China.
  • Higher kaempferol levels were found in NXYM wines.
  • YNDQ wines had the highest levels of dihydroquercentin-O-hexoside, while GSQL wines had the lowest levels.
  • YNDQ wines had higher levels of dihydroquercentin-O-rhamnoside, quercentin-3-O-glucuronide, and myricetin compared to all other regions.
  • Wines from NXYM and YNDQ had higher levels of kaempferol-3-O-glucoside than all other regions.

o   These values were double those found in GSQL and HBCL wines.

Hydroxybenzoic Acids

  •  3 hydroxybenzoic acids were found in Chinese wines.
  • Highest levels of total hydroxybenzoic acids were found in SDYT wines, and the lowest levels in NXYM wines.
  • SDYT wines had significantly higher levels of gallic acid, while NXYM wines had the lowest levels.


Hydroxycinnamic Acids

  • 4 hydroxycinnamic acids were found in Chinese wines.
  • GSQL and NXYQY wines showed the highest levels of total hydroxycinnamic acids.

o   These levels were nearly 5 times more than levels found in YNDQ wines.
  • GSQL wines had nearly 9 times more caffeic acid than YNDQ wines and 5 times more ethyl ρ-coumarate than wines made from NXYM and NXYQY grapes.
  • All wines had the highest percentage of gallic acid to total hydroxycinnamic acids.


Stilbenes

  • SDYT had the highest levels of stilbenes, while YNDQ wines had the lowest levels.
  • Trans-resveratrol was the most abundant stilbene in all wines, though was significantly variable between regions.

o   SDYT wines had nearly 7 times more trans-resveratrol than YNDQ wines.

Regional Similarities

  •  Cluster analysis revealed that wines from the Helan mountain of Ning-Xia (NXYM, NXYQY) and GSQL regions were similar in regards to their phenolic composition.
  • Wines from HBCL and SDYT regions were similar in regards to their phenolic composition.
  • The YNDQ wines were different in regards to their phenolic composition than from all other regions.


Conclusions

According to the results of this study, the differences in phenolic composition of Chinese wines in this study indicate that the accumulation of phenolic compounds in grapes is strongly influenced by terroir effects.  Going further, those regions that were geographically closer to one another had wines that were statistically similar to one another in regards to their phenolic composition than regions that were geographically isolated or further away.  NXYQY, NXYM, and GSQL, all of which were similar in phenolic composition, are all located in the drier area of Western China with a cool-warm climate.  HBCL and SDYT were found to be statistically similar to each other in regards to the phenolic content of wines, and were both located in the wetter areas of Eastern China with a warm climate.  Finally, YNDQ was found to be different from all other regions in regards to phenolic composition of wine, and was located on the plateau valley zone of Southwest China with a warm-arid climate.

Overall, these results clearly show terroir effects, and confirm that different regions in China, like other regions around the world, produce grapes that result in wines with statistically different phenolic compositions.  Terroir effects were found to be similar for wines from the Helan mountain of Ningxia and Qilian of Gansu; for wines from Changli of Hebei and the Yantai of Shandong; and finally with the wines from the Deqin of Yunan having significantly different terroir effects from all other regions.

This knowledge of terroir effects in China should give viticulturalists and winegrowers the knowledge necessary for maintaining and caring for vines from each particular region, as well as giving the winemakers knowledge necessary for creating a high quality wine made from grapes with very specific phenolic profiles.  By applying the knowledge gained from this study, grape growing practices and winemaking techniques may be adjusted accordingly in order to optimize wine flavor/aroma quality in China, at the very least with Cabernet Sauvignon grapes.

I’d love to hear what you all think of this topic!  Please feel free to comment below (any unauthorized html tags will be promptly removed).

Source: Li, Z., Pan, Q., Jin, Z., Mu, L., and Duan, C. 2011. Comparison on phenolic compounds in Vitis vinifera cv. Cabernet Sauvignon wines from five wine-growing regions in China. Food Chemistry 125: 77-83.

DOI:  10.1016/j.foodchem.2010.08.039



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jun 05 NO comments
agriculture, Cabernet Sauvignon, ecology, environment, grapes, pollen, research, Spain

Pollination Dynamics of Cabernet Sauvignon



In many plant species, including grape cultivars, autogamy (i.e. self-fertilization) is all that is necessary to successfully reproduce.  However, some cultivars require cross-pollination in order to reproduce and reach maturity.  The level of successful pollinations that occur will determine the grape yield, thereby understanding pollination dynamics of the grapevine is very important.

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Depending upon the species and cultivar, grapevines may be pollinated by wind or by insects.  One study in particular found that the presence of honeybee hives did not increase the number of fruit, but it did decrease the number of seedless grapes, thereby indicating that even though the grape yield was not increased by the presence of bees, the number of viable fruits had increased due to more efficient pollination by the bees.

To date, most studies involving pollination dynamics of grapevines examined finding links between annual pollen concentrations and grape yield, and how different environmental factors affect pollen dispersal.  According to the authors of the current study, there has been a resurgence in the study of grapevine pollination dynamics (Vitis vinifera, specifically), due to the increased presence of transgenic grapevines and the need to justify possible cross-pollination of these cultivars with other cultivars in the same area.

The goal of the study presented today was to further add to the scientific knowledge regarding pollination dynamics of Vitis vinifera, specifically anemophilous pollination (wind pollination), by examining airborne pollen concentrations.

Methods

The study vineyard was located in Zafra, in Badaioz in the southwest of Spain.  Vines were planted in rows 3 meters apart with 1.5 meters between each vine.  The main cultivar in the vineyard was Cabernet Sauvignon, though one small plot also contained Alphonse Lavallée, Cinsaut, Garnacha, Garnacha Tintorera, Mazuelo, Merlot, Morisca Real, Syrah, and Tempranillo.  All cultivars were grafted onto American rootstock.

Grapevine pollen concentrations were measured for the entire day, and also for each hour.  The average concentration per hour was calculated.  Hourly meteorological data was also measured.

Pollen grain dispersal was measured during sunlight hours of 1600 and 1830.  In order to take into account possible outside environmental influences, pollen concentrations of nearby species that were not grapevines were measured.  The most abundant plant nearby the vineyard was the olive tree, which was found no closer than 500m from the vineyard.

In order to measure the influence of height on the dispersal of pollen grains, samples were taken at 4 different heights in the center of the Cabernet Sauvignon vineyard and between the vineyard rows.  Pollen concentrations (both grapevine and olive tree) were measured at 0.5, 1m, and 2m above the ground.  This sampling took place on May 30, 2001.  For measuring horizontal dispersion of pollen, three locations 1.5m, 3m, and 4.5m from the vine were selected on the edges of the Cabernet Sauvignon vineyard.  14 samples were taken for 30 minutes on May 29th and 30th (6 samples at 1.5m, 4 samples at 3m, and 4 samples at 4.5m).  Mean concentrations of pollen (both grapevine and olive tree) were measured and calculated during these samplings.

To determine the effects of distance on pollen concentration in the vineyard, pollen concentrations of all cultivars were measured on May 22nd when 4 of the cultivars had more than 10% inflorescences with some open flowers.  Pollen concentration was measured by sampling each cultivar for 30 minutes.

Results

  •       Max daily concentrations of grapevine pollen occurred between May 26th and June 1st.
  •       The pollination period for Cabernet Sauvignon was only 7 days.
  •        During the max pollination period for Cab Sauvignon, the mean concentration of pollen was 62.7grains/m3 with a high concentration of 87.5grains/m3 noted on May 29th.

o   These concentrations are low for wind pollinated cultivars.
  •       Daily mean temperatures ranged from 15.1 to 28.5oC;  relative humidity ranged from 29.3 to 79.4%; daily wind speed ranged from 2.8 to 10.4km/hr; wind direction ranged from 60o to 253o ENE to SWS; and no rain was recorded during the sampling period.
  •        Relative humidity significantly affected pollen negatively

o   i.e. Higher relative humidity = lower pollen concentrations.
  •        Wind speed and wind direction had no significant effects on pollen concentrations.

o   Hourly and daily meteorological data affected pollen concentrations in the exact same manner.
  •       Pollination levels of Cab Sauvignon were at a minimum between 2300 and 0700 hours, and at a maximum during midday.
  •       Concentrations of olive tree pollen were greatest up to 0.5m aboveground and gradually decreased with increasing height aboveground.

o   This is possibly due to reduced wind speed at locations closer to the ground.
  •       Concentrations of Cab Sauvignon pollen were 200grains/m3 at 1m aboveground.

o   At 2m, there was a 10x reduction in pollen concentrations.
§  This result demonstrates the limited vertical dispersion of Cabernet Sauvignon pollen.
  •       Olive tree pollen concentrations remained steady, but pollen concentrations of Cabernet Sauvignon and other vinifera cultivars decreased beyond 1.5m after the end of the row.


Conclusions

The results of this study indicate that the dispersal capability of Vitis vinifera is relatively low, particularly for a wind-pollinated (anemophilous) plant.  This result is not surprising, considering the fact that Vitis vinifera species still retain some entomophilous (insect pollinated) characteristics from their ancestors, such as the production of sterile pollen by female flowers and the production of scented compounds which under true entomophilous species would attract insect pollinators.  The fact that Vitis vinifera possesses characteristics of both insect and wind pollinated plants indicates that this is a species in transition, with human selection driving the species toward a fully anemophilous state.

Finally, due to the pollination of this species only being effective at a short distance from the pollen source, if pollination were to take place between cultivars, it would need to occur between plants within very close proximity to each other.  Since wind speed and wind direction do not affect pollen concentrations, having a vineyard with transgenic vines neighboring a non-transgenic site would likely not result in the undesired cross-pollination between the two cultivars.

I’d love to hear what you all think about this topic!  We rarely see studies that are so heavily based in Ecology, so it’d be great to hear from you plant and insect lovers out there!  Please feel free to comment below (html tags will be deleted, so please do not post them).

Source: Muñoz-Rodríguez, A.F., Tormo, R., and Silva, M.I. 2011. Pollination Dynamics in Vitis vinifera L. American Journal of Enology and Viticulture 62(1): 113-117.

DOI: 10.5344/ajev.2010.10047




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