IMPACT OF CROP LEVEL AND HANG TIME ON THE COMPOSITION OF FOUR WINE GRAPE CULTIVARS FROM THE NIAGARA REGION. PDF Download
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Author: Luis Hugo Moreno Luna
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Category :
Languages : en
Pages :
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Author: Luis Hugo Moreno Luna
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Languages : en
Pages :
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Author: Gabriel Balint
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Category :
Languages : en
Pages :
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Author: Marlys E. Eddy
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ISBN:
Category :
Languages : en
Pages : 238
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Author: Amanda J. Vance
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Category : Companion planting
Languages : en
Pages : 141
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Vineyard management strategies, including vineyard floor management and crop level management, can be used to influence vine vigor and fruit composition. Two studies were conducted to evaluate the impact of these practices on Pinot Noir in Oregon's Willamette Valley. Managing crop levels is common in cool climate vineyard production though it is a costly practice. With economic pressures, the premium winegrape industry is questioning whether they can reduce production costs and increase yields without compromising quality. A crop thinning trial was conducted in 2010 and 2011 to address these concerns and to better understand the role of vine balance on fruit composition. Crop levels were moderately (35% crop removed) or severely (65% crop removed) thinned at pre-bloom, fruit set, lag phase, or véraison and compared to full crop treatments. In both years, crop thinning reduced yields but had no effect on berry weight or cluster size. In 2010, poor fruit set reduced overall yields, and thinning treatments resulted in very few differences in vine growth, cluster architecture or fruit composition, including total soluble solids (TSS), pH, titratable acidity (TA), yeast assimilable nitrogen (YAN), anthocyanins, phenolics and tannins. In 2011, yields were much higher due to high fruit set and larger cluster size. No differences were found in vine growth (leaf areas or pruning weights) or fruit YAN, but thinned vines had higher TSS and pH and lower TA than full crop vines at harvest. Fruit thinned at lag phase and véraison had higher TSS and lower TA than fruit thinned pre-bloom. Intensity of thinning had a stronger influence on anthocyanin and tannin concentration than timing, while phenolics were not impacted by either factor. Ravaz index values (fruit yield/pruning weight) below 2.25 and leaf area to yield ratios of 2.25 to 3.25 m2/kg improved fruit composition in 2011 as did later season thinning, though data from the remaining years of this study will provide more insight into appropriate crop load metrics for cool climate Pinot Noir. A second study was implemented in 2011 to determine the impact of crop thinning in vines with different levels of vegetative vigor caused by three vineyard floor management techniques: permanent grass (Festuca rubra spp. rubra) cover (grass), alternating grass cover and tillage (grass & tilled), and tillage of every alleyway (tilled). Crop was thinned at the BB stage of berry development (EL stage 73) to one cluster per shoot (half crop) or not thinned (full crop); all cluster wings were removed at the time of thinning. Tillage treatments had been in place four years prior to the start of the study and competition for nitrogen in grass caused reduced early season vine growth, leaf chlorophyll and canopy size at both bloom and véraison while crop thinning increased canopy size at véraison. Yields were altered by tillage and crop thinning treatments, as grass had fewer clusters per shoot and berries per cluster, and crop thinning reduced yields to 64.7% of full crop across all tillage treatments. At harvest, grass had the lowest TA while TSS and pH were not affected by tillage. Crop thinning increased TSS but did not impact pH or TA. Anthocyanins were affected by both tillage and thinning and were found to be related to vine yield, YAN, leaf N, and leaf area index. Tannins were highest in grass but were not affected by crop thinning, and phenolics were not changed by either factor. Few interactions between tillage and crop thinning were found, but as variables such as yield per vine were impacted by both treatment factors, monitoring long term effects of crop.
Author: Anton Prajitna
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Category : Grapes
Languages : en
Pages : 244
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Abstract: This study investigated the effect of cluster thinning on the quality and nutraceutical content of 'Chambourcin', 'Pinot noir' and 'Cabernet franc' wine grape berries and wines. In addition, this study investigated SO2 interference on wine nutraceutical content determination. In experiment 1, three vintages of Chambourcin and one vintage of Pinot noir crop level treated wines were evaluated for their composition, anthocyanin, total phenolic, antioxidant and total resveratrol content. Cluster thinning did not affect basic wine composition except pH. Cluster thinning, however, increased the total anthocyanins, total phenolics, and antioxidant capacity. Cluster thinning also increased the total resveratrol level in Chambourcin but not in Pinot noir wines. In experiment 2, we evaluated the effect of cluster thinning on yield parameters, vine growth, fruitfulness, canopy parameters, composition, anthocyanins, total phenolics and antioxidant capacity of 'Chambourcin', 'Pinot noir' and 'Cabernet franc' berries. We found that reponses cluster thinning treatments appear to be confounded with cold injury. Cluster thinning reduced yield in one out of two years of 'Chambourcin' and 'Pinot noir' vines. Cluster thinning increased cluster weight of Chambourcin but not Pinot noir and Cabernet franc. Cluster thinning decreased cropload of Chambourcin and one year of 'Pinot noir' vines. 'Pinot noir' vines under low crop level treatments had the most clusters/vine count prior to cluster thinning in 2004. Cluster thinning increased the anthocyanins, total phenolics and antioxidant capacity of Chambourcin berries linearly independent of harvest date. In experiment 3, we evaluated the extent of sulfite content interference on antioxidant determination (FRAP and ABTS assay) in red and white wines. Addition of SO2 up to 200 mg/L increased antioxidant capacity significantly. Addition of 100 mg/L SO2 generated on average 6.6 % and 64 % increase in antioxidant capacity for red and white wines, respectively indicating the extent of interference was much more pronounced in white compared to red wines.
Author: Steve P. Smit
Publisher:
ISBN:
Category :
Languages : en
Pages : 142
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Author: Alexander David Levin
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ISBN: 9781369615692
Category :
Languages : en
Pages :
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In recent years, deliveries of water for agricultural use in the San Joaquin Valley (SJV) of California have been reduced, or in some instances cut all together. Since 1980, the acreage of annual crops has decreased by 40%, while the acreage of perennial crops has increased by 77%. Recent research has shown that perennial crops have a higher potential for water conservation. Also, it has been shown that yields do not decrease significantly under some moderate levels of water stress. As trends in California agriculture shift away from traditional field crops, more detailed information is needed on the amount of water required to grow tree and vine crops. Vineyards now account for nearly half of the total acreage of woody perennial crops in California. Worldwide, approximately 10,000 grapevine cultivars are grown on over 8 million hectares of land covering a wide range of climates, from hot and dry to cold and wet. This apparent genetic diversity has led researchers to group different cultivars according to the drought responses of numerous vegetative and reproductive parameters. However, no studies have utilized an established cultivar trial to directly compare multiple cultivars grown at the same site and subjected to the same water stress. Growers in the SJV would have the most potential to conserve water if the more was known about how individual cultivars response to drought at different times of the growing season. Seventeen different red wine grape V. vinifera L. cultivars grafted on to the same rootstock (1103P) were grown in a replicated cultivar trial, and subjected to three different deficit irrigation regimes over four years in order to manipulate [psi][subscript l] at various times throughout the growing season. An early deficit treatment (ED) received no applied water from berry set until veraison, and then was irrigated at 50% of ET[subscript c] from veraison until harvest. A late deficit treatment (LD) was irrigated at 100% ET[subscript c] from berry set until veraison, and then received no applied water until harvest. The sustained deficit treatment (SD) was irrigated at 50% of ET[subscript c] from berry set until harvest. Previous work has categorized wine grape cultivars into ‘isohydric’ or ‘anisohydric’ groups based on the response of stomatal conductance (g[subscript s]) to plant water status (leaf water potential ([psi][subscript l])). Significant differences in l among cultivars were observed during both time periods, but the effects of the water deficits were consistent across growing seasons. There were no significant differences in maximum stomatal conductance (g[subscript max]) among cultivars. Cultivar-specific responses of g[subscript s] to [psi][subscript l] did not separate into two distinct groups, but were broadly distributed based on a negative relationship between the [psi][subscript l] threshold for the beginning of stomatal closure at 95% of g[subscript max] and the rate of stomatal closure. Cultivar mean [psi][subscript l] values were positively related to the [psi][subscript l] threshold for the end of stomatal closure at 25% of g[subscript max]. Potential mechanisms of stomatal closure related to vascular anatomy are discussed. The quantitative models of g[subscript s] response to [psi][subscript l] presented in this study provide baseline threshold [psi][subscript l] values from which to compare cultivars in future research. With increasing competition for water resources, accurate information regarding crop water requirements is needed for informed irrigation management decisions. Early (preveraison) water deficits (ED-treatment) consistently and significantly reduced yields compared to the control across all years and cultivars, but the late (post-veraison) deficit (LD) treatment vines were not different from the control. The reduction in yield with ED was primarily due to a significant reduction in berry fresh weight (FW), and clusters per vine, with little change in berries per cluster. The LD treatment had a limited effect on berry FW and did not affect other yield components. Variation in yield was mostly due to berries per vine rather than berry FW, although this depended on cultivar. There were also cultivar differences in the proportion of variation in berries per vine explained by either clusters per vine or berries per cluster. Irrigation treatment or applied water amounts did not have a consistent effect on the water footprint but it was strongly dependent on yield. Implications of the timing of water deficits on the productivity of wine grapes in the SJV are discussed with respect to cultivar differences in yield formation. Previous research has shown that berry size is the most important component in grapevine yield, and that the sensitivity of grape berry growth to water deficits depends on the timing of those deficits. Berry growth was significantly reduced in ED for every cultivar, and berry absolute and relative growth rates (AGR and RGR, respectively) were significantly lower at the first measurement date after imposition of irrigation treatments. RGR was consistently higher in ED compared to SD and LD postveraison, but lost growth was not made up for in ED berries at harvest. AGR and RGR were significantly more sensitive to vine water status preveraison compared to postveraison for all cultivars. Ripening rate was highly conserved across cultivars and years, and was only slightly (but significantly) reduced in ED compared to SD and LD. In comparison, sugar translocation rate varied widely among cultivars and years, and was significantly different among all irrigation treatments. Sugar translocation rate depended strongly on berry size at veraison, but ripening rate did not. Irrigation treatments and cultivars affected the timing of ripening events independently with no interaction, and the timing of events was more dependent on berry sugar concentration (TSS) than days after anthesis (DAA). The results of this study may provide growers with cultivar-specific pre- and postveraison vine water status targets for irrigation scheduling, as well as assist with the timing of vineyard operations through better understanding of the timing of ripening events near the end of the season.
Author: Erik W. Brasher
Publisher:
ISBN:
Category : Grapes
Languages : en
Pages : 106
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Author: Harold Gordon Swartwout
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Category : Agriculture
Languages : en
Pages : 44
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Author: Jimena Balic
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ISBN:
Category :
Languages : en
Pages : 580
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