Centre for Viticulture and Oenology

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Recent Submissions

  • PublicationOpen Access
    Berry composition and wine quality of Pinot noir as affected by leaf area to crop load ratio
    (Lincoln University, 2015) Qin, Yunxuan
    The effect of vine leaf area (LA) relative to crop load (CL) was investigated in the cool climate growing region of Canterbury, New Zealand, using Pinot noir (clone 10/5) Vertical Shoot Positioning (VSP) trained vines. Three weeks after fruit-set, vine leaf numbers were standardized with two of the four basal leaves retained in all cases. LA treatments were 12 leaves (1L), 6 leaves (0.5L) or 3 leaves (0.25L) per shoot. CL treatments were full crop (1C), half crop (0.5C) or quarter crop (0.25C) by removing equal numbers of primary and secondary clusters, producing five different treatment ratios (TMR), “0.25”, “0.5”, “1”, “2” and “4”. Treatments were applied in a 4-replicate split plot design. Grapes were harvested on April 4, 2014 and replicates 1 & 4 and 2 & 3 were combined to make two wines from each treatment. LA/CL (cm²/g) was estimated from a subsample of shoot leaf areas divided by total yield per vine after harvest. Starch dry weight in roots was not affected by crop load, but was decreased with leaf removal, while pruning weight was increased with increasing TMR, indicating that the fruiting capacity for next season could be reduced by limited leaf numbers. Juice °Brix was negatively, while juice pH was positively, related with increasing levels of leaf removal. Total red pigments, tannin concentration and total phenolics in skin extracts were decreased by greater leaf removal (p < 0.05, p < 0.01 and p < 0.05, respectively). Results suggest shading appeared not to be a limiting factor for the synthesis of phenolic compounds, or to have an impact on fruit composition in general (i.e. potassium, malic or tartaric acids). The concentration of total red pigments, tannin and total phenolics in wine were not significantly different between treatments, though some visual differences were observed using the CIELab method on native wine samples. HPLC analysis of wine showed that two procyanidins dimers, rutin, caffeic acid and caftaric acid were affected by crop removal only, while quercetin, quercetin-glucuronoide 1 and protocatechuic acid were affected by leaf removal only. Kaempferol-glucoside, p-hydroxybenzoic acid and p-coumaric acid were affected by both leaf removal and crop removal treatments. GCMS analysis showed the concentrations of fatty acids and some esters were higher when more leaves and more crop were retained, and that the concentrations of C6 alcohols were positively related with TMR. Some wine parameters showed the same patterns as that found for grapes, including pH, colour hue, degree of red pigment colouration, and kaempferol-glucoside concentration, along with the CIELab visual colour pattern. Thus, the fruit characteristics can be transferred into wine. It appears that the most appropriate LA/CL or TMR to produce quality wines were not the extreme values (e.g. the highest or lowest LA/CL, or TMR =“0.25” or “4”) based on the chemical analysis in this study. In fact, lower to medium levels of leaf and crop removal were desired, based on the concentrations of phenolics, volatile aroma compounds, carbohydrate in grapevine roots, along with other parameters measured in this project.
  • PublicationOpen Access
    Manipulating the functionality of grape seeds products through reflective mulching and wine fermentation
    (2008) Bekhit, Alaa E. A.; Qiao, W.; Creasy, Glen; Hider, Richard; Dawson, Christopher O.
    Poster presentation of research carried out to investigate the effect of reflective mulching and wine fermentation on the fatty acids and the phenolics profiles of grape seed.
  • PublicationOpen Access
    Measuring grape damage as an indicator of bird pressure
    (2009) Saxton, Valerie P.
    The Falcons for Grapes project was originally funded by SFF and NZ Winegrowers with joint objectives of conservation and of establishing falcons in vineyards where they would provide some bird control. In conjunction with the Falcons for Grapes project, Sustainable Farming Fund (SFF) funded the development of a robust method for surveying bird damage to grapes, followed by funding for a 3 year survey of grapes where falcons were established. This is the final report from that 3 year project.
  • PublicationOpen Access
    Influence of natural reflective mulch on Pinot noir grape and wine quality
    (Lincoln University. Centre for Viticulture and Oenology., 2007-12) Creasy, Glen; Leal Perez, Gerardo; Crawford, Michelle; Ibbotson, I; Tompkins, J; Creasy, Kirsten; Wells, Gilbert; Nicol, I; Harrison, Roland; Sherlock, Robert; Hider, Richard; Gladstone, P; Kavanaugh, J; Finn, T; Sutherland, A; Steans, Graeme
    The intention of conducting this project is to investigate the potential of addressing the problem of excessive sugar (potential alcohol) levels in Pinot noir at harvest. This was attempted by modifying the ripening process through the use of a natural reflective mulch (mussel shells), which are also a by-product of the Nelson area seafood industry.
  • PublicationOpen Access
    The influence of vine vigour and canopy ideotype on fruit composition and aroma of Sauvignon Blanc
    (Lincoln University, 2009) Sutherland, Melissa J.
    The influence of soil texture on canopy growth, vine yield, and fruit composition of Sauvignon blanc were assessed on a mature vineyard from the Rapaura area in Marlborough. The subject vines were mature Sauvignon blanc in a commercial vineyard trained to four cane VSP and planted with a north south orientation. Row and vine spacings were typical of the area at 3m x 1.8m. Four areas of different soil texture were identified using trunk circumference measurements, visual assessment of the surface soil and aerial photographs to identify changes in vine growth. Soil pits were excavated at a later date to determine root numbers and record the soil texture in the different areas. Two crop treatments were imposed on half of the plots at approximately 50% veraison: unthinned crop and 50% crop. A shading treatment was also imposed at 50% veraison where three sets of tagged shoots had bunches that were exposed to sunlight, bunches that had some natural shading from leaves or bunches that had paper bags fastened over each to provide a completely shaded environment. Vine vegetative vigour for each plot was assessed during the growing season using the Point Quadrat method and at pruning using bud counts and pruning weights. Thirty berry samples were collected from the 32 plots and analysed weekly for soluble solids and berry weight. Harvest of bunches from the tagged shoots occurred on two different dates with the first harvest picked when fruit from one soil and crop treatment had reached 21 °Brix. The second picking took place just before the commercial harvest, which coincided with last soil and crop treatment reaching 21 °Brix. Bunches from each tagged shoot were weighed, frozen and later analysed for soluble solids, pH, organic acids, and methoxypyrazines. Vines on very stony textured soils had small trunk circumferences with a high root density and yield to pruning weight ratio compared to those growing on deep silt soils. Vines on deep silt soils had more vigorous canopies with large shoots and a higher leaf layer number. The target soluble solids was reached first by the vines on the very stony plots despite the higher crop load with soil texture appearing to be a dominant factor by influencing the time of flowering. Cluster shading decreased soluble solids, consistent with other studies, whilst crop thinning resulted in an earlier harvest. This was contrary to popular opinion that crop thinning at veraison would have no impact on sugar accumulation. pH and organic acids were unaffected by shading or bunch thinning. Vines growing on deep silt soils had a significantly higher level of total acidity and malic acid than those on the stony soils. At harvest, methoxypyrazine levels were very low compared to previously reported figures for Marlborough, which may have been a result of sample preparation. IBMP was significantly higher on deep silt soils, however, with no impact from the shading or crop treatment. The findings are consistent with the hypothesis that IBMP synthesis may be increased by the number of leaves surrounding bunches (Roujou de Boubee, 2003). The results suggest that soil texture plays a dominant role in influencing Sauvignon blanc flavour and aroma and due consideration should be given to vineyard layout and site selection prior to new plantings taking place.