Clonal Testing of Wine grapes in the San Joaquin Valley
This is an ongoing study to evaluate promising, virus disease-free FPMS clonal material for the San Joaquin Valley. Data collection continued (fourth fruiting year in 2002) with the Chardonnay, Cabernet Sauvignon, Merlot, and Zinfandel/Primitivo trials. These trials were planted with 6 clones each in 1997 in order to evaluate clonal differences in a warm climate region. A new Barbera trial was planted in summer, 2000; vine training was completed in 2002. Chardonnay. Vine yields among clones were similar in 2002; however, differences in fruit characteristics and composition were shown. The greatest contrast was between Clones 4 and 15. Clone 4 had the fewest and heaviest clusters of higher berry numbers and with good fruit composition (high TA and low pH). It has had comparatively high fruit soluble solids and TA and low pH in past years. However, Clone 4 was of higher bunch rot incidence than some of the others in 2002. Clone 15 had the smallest berries and tended to have lighter clusters and less rot; however, it was of higher fruit pH than some of the others. Thus, Clone 4 favors fruit composition, Clone 15 favors small berries and cluster and lower bunch rot potential. The other Clones ? 6, 18, 20 and 37 ? showed comparatively minor differences in 2002.Cabernet Sauvignon. Clonal differences were small in 2002, with only berry weight showing significant differences. Clones 2 and 24 had the lightest berries. Their similarities have been reported in previous years. The others have been mostly similar to one another. While the overall differences have not been great, the smaller berries with Clones 2 and 24 and the trend toward larger berries of Clone 22 may be of importance to San Joaquin Valley growers and vintners. However, the smaller berry characteristics have been accompanied with some sacrifice in yield in previous years. Concerns of berry size and yield will depend on a grower?s or vintner?s production goals.Merlot. The Merlot clones showed significant differences in all of the measured parameters except bunch rot incidence and number of berries per cluster. Clone 11 again produced the heaviest berries with the highest fruit pH. It also had the most bunch rot in 2001. Clone 14 again produced fewer clusters with smaller berries than some of the others, with corresponding lower vine yields and higher oBrix. Clone 10 was the most fruitful and had the highest fruit TA. It has also performed well in all yield and fruit composition parameters in previous years. Thus, Clone 10 has consistently shown good characteristics, while Clone 11 shows some unfavorable characteristics for warm climates. While Clone 14 has small berries, its lower yield is a disadvantage, unless this can be improved with higher pruning levels. Zinfandel/Primitivo. Clonal differences were again mostly different between the Zinfandel Clones (1A, 2 and 3) and the Primitivo Clones (P3, P5 and P6). Berry weights were lowest with P3 and P5; berry soluble solids were highest in the three Primitivo clones. However, titratable acidity and berry skin anthocyanins were not different among the clones. The Primitivo clones tended to have higher cluster numbers than Zinfandel. None of the other yield parameters ? cluster weight, berries per cluster and total yield per vine ? showed clonal differences. Bunch rot incidence was higher in the Zinfandel clones as compared to Primitivo with the exception of P5, which was not different than Zinfandel 2. Overall, the Primitivo clones are showing advantages over the Zinfandel clones in vine fruitfulness, fruit soluble solids, smaller berries and less bunch rot. Primitivo 2 is showing the highest yield potential and with good fruit composition.The variations of clonal response point to the importance of multiple year data collection. While some consistency of clonal response is apparent in these comparisons, our previous work has demonstrated the need for a minimum of 4 years of full production data to determine longer term vine response. The influence of sweetness and of flavor (vegy or fruity) on perception of astringency was examined in red wine. Astringency intensity was significantly lower in the sweetened wine, than the base wine or flavored wines. Since aspartame was used, and no increase in viscosity occurred upon sweetening, the suppression of astringency is solely due to cognitive interaction. When fruitiness was rated in sweetened and flavored wines, a similar cognitive enhancement was observed in that the sweetened (unflavored) wine was rated fruitier than a fruity-flavored wine or the base wine. Consistent with previous studies, astringency was rated less intense when artificial saliva containing salts was introduced at a medium flow rate (5 ml/min) than at a low flow rate (o.5 ml/min). When wine was sipped repeatedly, the maximum intensity (IMAX) of astringency increased with each sip at low and medium flow rates of introduction of the artificial saliva, although it decreased upon successive sips at high flow rates (8 ml/min). When 3g/L gelatin was added to the artificial saliva the same effect was observed. However, there was no difference in astringency IMAX between artificial saliva with and without protein at either flow rate for any sip, which indicates that further research is needed to understand perception of astringency.