WINE GRAPE TRIAL REPORT

Transcription

1 WINE GRAPE TRIAL REPORT Stellenbosch, Western Cape Louisvale 2008/09 season Introduction A trial was conducted in the Stellenbosch area on an older wine grape vineyard to determine whether AnnGro alone, ComCat alone or in combination can contribute to yield and quality improvement. Material and methods The following treatments were applied in a randomized block design with each treatment replicated four times: 1. Control 2. ComCat FRUIT (100 g/ha) 3. AnnGro (120ml/ha) 4. ComCat FRUIT (100g/ha) + AnnGro (120 ml/ha) The first application was at 5-10 cm new shoot growth on the 16 th October 2008 whereafter another three applications followed at three week intervals. For the 1 st application 500 litres of water/ha was used, followed by 750 litres of water/ha for the second application. The 3 rd and 4 th applications were sprayed with 1000 litres of water. The amount of plants per hectare was approximately The cultivar was a Chardonnay. Each plot (18m 2 ) was harvested separately, and the bunches counted and weighed. A sample of 3 bunches per plot was taken randomly for each plot and sent to Koelenhof Wine Cellar s laboratory for quality analysis. Statistical analysis was performed using the NCSS statistical program at a 95% significance level. Differences between treatments were calculated using the Tukey-Kramer comparison test. Results and discussion In terms of yield, both the ComCat and ComCat + AnnGro treatment revealed a tendency to increase the yield, although not significantly. Where AnnGro was applied on its own a small reduction in yield, although not significant, was observed (Figure 1).

2 n of bunches/ha bunches/ha Yield (kg/ha) Yield on wine grapes - Stellenboch Figure 1 Yield of Chardonnay grapes. (LSD 0.05 = ) [CC = ComCat] Interestingly, the highest number of grape bunches was counted in control plots, while all of the treated plots had less bunches per hectare, however not significantly less (Figure 2). Chances are that this was not related to the treatments but was merely an experimental variation. Number of bunches on wine grapes - Stellenbosch Figure 2 Amount of bunches of Chardonnay (LSD 0.05 = ) [CC = ComCat] For the wine grape farmer the average bunch weight is probably not so important, although it was very interesting to observe that the AnnGro as well as the ComCat + AnnGro combination treatments contributed to the highest average bunch mass (Figure 3), while ComCat applied on its own resulted in the opposite, although not statistically significant. This was especially of interest due to the differences in bunch number as shown in figure 2. The control and ComCat

3 mass (g) treatment plots that had the highest number of bunches showed the same tendency to have bunches with lower mass while the opposite tendency applied for the other two treatments. This confirmed that the number of bunches per hectare and the bunch mass is correlated. But, what really stood out in this trial is the fact that the lowest amount of bunches per hectare was counted in the ComCat + AnnGro combination treatment plots while this treatment eventually produced bunches with the highest fresh mass as well as the highest total yield. The latter scenario is in concert with previous findings on both wine and table grapes. ComCat is known to have a membrane energising effect that accelerates the translocation of sugars from the source (leaves) to the sinks (berries) that affects the berry size and fresh mass Average bunch mass of wine grapes - Stellenbosch 0809 Figure 3 Average bunch mass of Chardonnay grapes. [CC = ComCat] Quality parameters The highest acid content was found in the grapes sprayed with AnnGro only (Figure 4), while ComCat, as well as the ComCat + AnnGro combination treatment reduced the amount of acids (although not statistically significant). According to the standards set by Koelenhof Wine Cellars, all treatments were in regulation with Class 1 Chardonnay grapes. (The total acid percentage should be more than 7 % for a Class 1 category).

4 sugar content (balling) Total acid % Total acid percentage on wine grapes - Stellenbosch Figure 4 Acid content of Chardonnay grapes. (LSD 0.05 = 1.122) [CC = ComCat] All treatments, with the exception of AnnGro, contributed to a higher sugar content in berries, as shown in Figure 5. The ComCat treatment reduced the acid content substantially and most compared to other treatments (Figure 4), and this was indirectly proportional to the sugar content (Figure 5) in berries Balling (sugar content) of wine grapes - Stellenbosch Figure 5 Sugar content of Chardonnay grapes products (LSD 0.05 = 1.52). [CC = ComCat]. For a class 1 quality grape the sugar content must be more than 20 balling, while for class 2 it must be 19 or more and for a class 3 it must be above18. The lower the ph the better the quality (norm for class 1 is lower than 3.3). Although the ph of juice from treated grapes was highest, compared to the control, it was still within the norm. Both

5 ph AnnGro and the ComCat + AnnGro combination treatment resulted in lower juice ph compared to the control (Figure 6). ph on wine grapes - Stellenbosch Figure 6 ph of Chardonnay grapes (LSD 0.05 = 0.08) [CC = ComCat] Conclusion The hypothesis that AnnGro possess the capability to enhance the uptake of other molecules was confirmed in terms of yield. The ComCat + AnnGro combination treatment was the only treatment revealing a tendency to increase yield by more than 6%, compared to the untreated control. However, what makes this remarkable is the fact that less bunches ha -1 were counted in the plots treated with ComCat + AnnGro. The increase in individual bunch mass by 15 g bunch -1 (+18%) under the influence of this treatment correlated positively with the yield results. From a quality perspective, it is known that ComCat has the characteristic to increase the sugar content in fruit. In both treatments where ComCat was sprayed, alone or in combination with AnnGro, the tendency to increase the sugar content in berries was observed. However, for this specific cultivar, Chardonnay, a high acid content is preferable. Although the ComCat and ComCat + AnnGro combination treatment tended to reduce the acid content in berries, the values were still well within the norm. This was also the case for the ph of berry juice. It can be concluded from this trial that the addition of AnnGro, as an uptake enhancer, to other products such as ComCat, may have positive contributions in terms of yield and quality on wine grapes. In the case of Chardonnay, the latter treatment showed a tendency to increase yield while all quality parameters remained within the norm.