Allen, M. S., Lacey, M. J., Harris, R. L. N., & Brown, W. V. (1990). Viticultural. Influences ... Thank you to Andy Swann and Mary Plaisted for help in collecting data.
Effects of Leaf Removal on Inner-Canopy Light Levels and Vine Function of Vitis vinifera cv. Merlot Grapevines Jennifer Wolf, Vinay Pagay PhD, Elizabeth Tomasino PhD Food Science Dpt OSU BioResource Research Interdisciplinary Program, Oregon State University, Corvallis, OR Southern Oregon Research and Extension Center, Oregon State University, Central Point, OR
Introduction
Figure 1: Photos of vine canopies after leaf removal treatments were applied. A: N; B: CLR; C: SLR1; D: SLR2
Weekly measurements included shoot length and growth rate, canopy light interception using EPQA as per Meyers (2008)5 , leaf area index, and canopy temperature and humidity. Bi-weekly measurements included gas exchange and chlorophyll fluorescence, and vine water potential using a pressure chamber. Berry harvests were done at pea-size, bunch closure, 50% véraison, midway to harvest, and harvest. At harvest, berry diameter and weight were recorded. 50 berries from each vine were randomly collected, frozen in liquid nitrogen and stored in a -80°F freezer for MP analysis. MP analysis was done via GCMS machine according to the procedure outlined by Ryona (2009). RESEARCH POSTER PRESENTATION DESIGN © 2012
www.PosterPresentations.com
2500 2000 1500 1000
Fruit Set
Pea Size
500
50% Veraison Bunch Closure
0
Cumulative GDD Daily Average Temperature
90 80 70 60 50 40 30 20 10 0
Table 1: Light Measurements over the 2014 growing season Avg ± SE Letters indicate significant differences with α= 0.05
Temperature (°F)
3000
Industry Recommendations • Conventional Leaf Removal • Sufficient for warm climate vineyards • Severe Leaf Removal • More benefits for cool climate vineyards – Ex: disease control
Figure 2: Average Berry Temperature 31 30
Temperature (°C)
Commercial practices by the vineyard were applied to our vines the same as the rest of the vineyard. Due to this, the soil was never dry and vine topping and hedging was done on all vines. Results showed that leaf removal had no significant effect on photosynthesis, gas exchange, or growth rates of either primary or secondary shoots. Leaf removal had the largest effect on microclimate in the cluster zone of the canopy. Table 1 shows the results of the light measurements and include leaf area index (LAI), canopy light interception (T), occlusion layer number(OLN), and cluster exposure flux availability(CEFA). OLN and CEFA were calculated according to the process described by Jim Meyers and Justine VandenHuevel5 . Both SLR treatments showed a significant (α= 0.05) decrease in LAI when compared to CLR and N. T showed a significant decrease in SLR from N that further differentiated itself as the season progressed. All leaf removal treatments had the same significant difference from N after leaf removal. CEFA results showed a trend between the severity of leaf removal and significantly increased levels of light in the cluster zone. Berry temperature data was collected using an IR thermometer and showed a similar trend as light measurements.
No Leaf
29
No Removal LR
28
Conventional CLR
Leaf Removal
27
Severe Leaf SLR 1 Removal 1
26 25
Severe Leaf SLR 2 Removal 2
24 23
No LR
CLR
SLR 1
SLR 2
GCMS analysis showed a significant difference between phenological dates and treatments. Figure 3 shows the average results for GCMS analysis and the siginificant difference for each treatment at each date.
No Leaf Removal
180 160 140 120 100 80 60 40 20 0
Conventional Leaf Removal Severe Leaf Removal 1 Severe Leaf Removal 2
50% Veraison
Acknowledgements Thank you Oregon Wine Board for the start up funds. Thank you to RoxyAnn Winery of Medford for the use and maintenance of their vines for this experiment. Thank you to Andy Swann and Mary Plaisted for help in collecting data. Thank you to Elizabeth Tomasino for the use of her lab and equipment.
References
Figure 3: IBMP Concentrations Over the 2014 Growing Season
Pea Size
Phase 1: Field Work • Field testing showed a positive correlation between the severity of leaf removal and the amount of sunlight in the cluster zone of the canopy. • Severe leaf removal 1 and 2 significantly increased the amount of light reaching the fruit while not affecting vine function. Phase 2: MP Analysis • Standard berry metrics showed only total anthocyanins showed a significant difference between No LR and SLR2. • Initial wine sensory analysis via trained sensory panel shows a trend of decreasing green taste with increasing leaf removal severity. • GCMS analysis showed that leaf removal resulted in a significant difference in MP concentrations. • No significant difference between leaf removal treatments
Julian Day
Concentration (ng/L)
This project took place in a commercial vineyard in Southern Oregon using Vitis vinifera cv. Merlot. Four treatment groups were established in a randomized complete block. Treatments were applied two weeks post-bloom. Figure 1 shows the different treatment groups, these were: • No leaf removal (N) • Conventional Leaf Removal (CLR): 3-4 leaves removed above the cluster zone on both sides of the canopy. • Severe Leaf Removal 1 (SLR1): 7-8 leaves removed from the morning (East) side and 3 removed from the afternoon side above the cluster zone. • Severe Leaf Removal 2 (SLR2): 11-12 leaves removed from the morning side and 3 removed from the afternoon side above the cluster zone.
Figure 1: Temperature and Degree Growing Days for the Growing Season 2014
Discussion
158 164 170 176 182 188 194 200 206 212 218 224 230 236 242 248 254 260 266 272 278
Methods
Results from phase one of this project focused on the effects of leaf removal on vine balance and function. Weather during the growing season in Southern Oregon was warmer than average. Figure 1 shows the daily average temperature and growing degree days for the region. Growing Degree Days (Base 50 °F)
Methoxypyrazines (MPs) are organic compounds commonly found in wine grapes that cause an undesirable, green, herbaceous flavor in wine1 . Research has shown a correlation between MP concentrations in grapes and the amount of sun exposure and temperature in the cluster zone of the vine2,3 . This project examines the effects of leaf removal on cluster zone light levels and reduced MP concentrations while establishing a healthy vine balance for the growing season4 . This project is composed of two phases. Phase one focuses on treatment application, light measurements, and vine balance. Phase two focuses on MP analysis.
Results
Harvest
Wine
1. Allen, M. S., Lacey, M. J., Harris, R. L. N., & Brown, W. V. (1990). Viticultural Influences in Methoxypyrazines in Sauvignon Blanc. Wine Industry Journal, 44-46. 2. Lee, J., & Skinkis, P. (2013). Oregon ‘Pinot noir’ grape anthocyanin enhancement by early leaf removal. Food Chemistry, 139(1-4), 893-901. 3. Palliotti, A., Gatti, M., & Poni, S. (2011). Early Leaf Removal to Improve Vineyard Efficiency: Gas Exchange, Source-to-Sink Balance, and Reserve Storage Responses. American Journal of Enology and Viticulture, 62(2), 219228. 4. Dunlevy, J., Soole, K., Perkins, M., Nicholson, E., Maffei, S., & Boss, P. (2013). Determining the Methoxypyrazine Biosynthesis Variables Affected by Light Exposure and Crop Level in Cabernet Sauvignon. American Journal of Enology and Viticulture, 64(4), 450-458. 5. Meyers, J., & Vanden Heuvel, J. (2008). Enhancing the Precision and Spatial Acuity of Point Quadrat Analyses via Calibrated Exposure Mapping. American Journal of Enology and Viticulture, 59(4), 425-431.
