This is an ongoing study to evaluate promising, virus disease-free FPMS clonal material for the San Joaquin Valley. Completion dates for past trials are: French Colombard and Chenin blanc (1994), Barbera (1995), and Muscat of Alexandria (1997). Trial blocks of 3 clones each of Grenache, Sangiovese, and Muscat blanc were established in 1993; data collection was initiated at harvest, 1995. Significant clonal differences have been measured over 3 or 4 years in these cultivars as follows: Muscat blanc. The Milan introductions, clones 3 and 4 have been distinctly better than clone 1, an older introduction into California. Clone 1 had fewer and heavier clusters with larger berries, less fruit yield, and more bunch rot. Overall, Clone 4 would be preferable because of its consistent high fruitfulness (3 years) of smaller clusters (1997 only) with less rot and earlier fruit maturation (compared to Clone 3), Clone 4 should be promoted, while Clone 1 should be discouraged, for all new plantings. Grenache. These were all California selections. The trial included a genetic comparison [Clone 1A (Gallo vineyard) vs. 3 (Jackson vineyard), both non-heat-treated] and a heat treatment comparison (1A vs 2, clone 2 being a 62-day heat treatment of Clone 1A). Genetic differences have been more apparent than heat treatment differences, with clone 3 producing the highest yield, lowest fruit maturation and most bunch rot. Clones 1 and 2 (heat treatment comparisons) were more similar, except for Clone 2’s heavier berries of slightly lower pH and higher TA and more bunch rot in one year (19988). Overall, Clone 1A would appear to be preferable due to its higher cluster numbers with smaller berry size and the least rot potential. For yield alone, Clone 3 would be preferable, but with some delayed fruit maturation and greater susceptibility to bunch rot due to heavier berries and clusters. Sangiovese. This cultivar demonstrated distinct clonal differences, with Clone 4 showing the least promise due to poor fruit composition (low TA and high pH), high bunch rot incidence, and low total anthocyanin content of experimental wine. Clone 2 may be preferred over Clone 3 due to its smaller berries and higher vine fruitfulness and yield. However, crop load management would be more important in Clone 2 as its fruit maturation was delayed as compared to less fruitful Clone 3. Further work is planned to determine if crop load adjustment of Clone 2 favors its fruit composition while retaining smaller berry size as compared to Clone 3. Experimental wine lots made from the clones in 1997 demonstrated minor differences in wine making or quality characteristics. Clone 4’s musts and wines were of lowest acidity and highest pH which were reflective of its harvest berry sample analyses. All wine samples were fairly low in color intensity. The Muscat blanc and Grenache trials are now complete. One more year of study with Sangiovese is anticipated to study crop load comparisons. This will determine under what conditions Clones 2 or 3 should be recommended for the best fruit composition with optimum yields. Chardonnay, Cabernet Sauvignon, Merlot, and Zinfandel/Primitivo trials were planted in 1997 at the request of the AVF Research Committee. Six clones of each cultivar will be studied for comparison under warm climate conditions.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF1998-10-18 12:02:292017-10-18 12:03:06Clonal Testing of Wine Grapes in the San Joaquin Valley