Minimal Input Production Systems Affect Yield and Juice Quality of 'Sunbelt' Grapes in California's San Joaquin Valley

Abstract

<jats:p>'Sunbelt' is a juice grape cultivar developed by the Univ. of Arkansas. This cultivar produces 'Concord'-type juice and is adapted to warm climatic conditions of the southern United States. Preliminary evaluation showed that 'Sunbelt' has potential to produce high-quality juice under the hot climatic conditions of the San Joaquin Valley. A study was conducted during the 1998 and 1999 growing seasons to further evaluate the adaptation of 'Sunbelt' to the San Joaquin Valley and determine the response of this cultivar to selected pruning methods. Vines were grown for two seasons without use of insecticides, fungicides, or herbicides. Vines were subjected to four pruning treatments: severe hand pruning (60-80 nodes retained/vine); moderate hand pruning (120-160 nodes retained/vine); machine pruning with hand follow-up (160-180 nodes retained/vine); and minimal pruning (200-400 nodes retained/vine). Vines were trained to a Geneva Double Curtain trellis system. Yield, components of yield, and juice quality were significantly impacted by pruning treatment. In both seasons, mechanized systems of pruning (machine and minimal) produced higher yield than hand pruning. Minimal pruning resulted in the highest yield (42 t·ha<jats:sup>-1</jats:sup>) in 1998, while yield from the machine-pruned vines was highest (29 t·ha<jats:sup>-1</jats:sup>) in 1999. Minimally pruned vines had the highest clusters/vine and lowest cluster weight among the treatments. The extremely high yields obtained for the minimal pruning treatments produced fruit that was less mature resulting in juice with lower soluble solids than the other treatments in 1998. However, in 1999 the juice from minimally pruned vines had the highest soluble solids. Sensory analysis of juice produced in 1999 showed that the juice from the machine-pruned treatment had the least color intensity. Sensory analysis showed that minimal and severe hand pruning were ranked higher for sweetness than machine and moderate hand pruning. In the second year of the study, the juice from the minimal-pruned and severe hand-pruned treatment were preferred over the moderate hand-pruned treatment or the machine-pruned treatment.</jats:p>

Mechanical Pruning and Soil Organic Amending in Two Terroirs. Effects on Wine Chemical Composition and Sensory Profile

“…Total pigments were significantly lower in MEC in 2014 and 2015, which is in accordance with the difference observed in total anthocyanin content and is probably a consequence of the yield increase promoted by MEC that reduced the leaf area to production ratio (Botelho et al 2020). Striegler and Lake (2002) also found a significant decrease in total pigments with machine pruning, while Main and Morris (2008) found no differences. Because in 2014 the polymerization index was not different between pruning treatments, MAN had more polymerized pigments than MEC.…”

Initial Response of ‘Concord’ and ‘Sunbelt’ Grapes to Pruning and Fruit Thinning

“…Morris et al (2007) reported 0.38 kgÁm -1 pruning weight on GDC-trained 'Sunbelt' on shorter 1.8 · 2.7 m row spacing with yield to pruning weight ratio of 12. GDC-trained 'Sunbelt' grown in the San Joaquin Valley of California with 2.1 · 3.6-m spacing had an average pruning weight of 0.26 kgÁm -1 with a yield to pruning weight ratio of 16 (Striegler et al, 2002). Morris et al (2007) and Striegler et al (2002) had 5 kg/vine less fruit yield than handpruned vines in this experiment.…”

“…The lower pruning weights may also be due to the warmer growing season in 2005 with 39 d over 90°F compared with 5 d in 2004 (weather reporting station was Arkansas Agricultural Experiment Station 32444, Fayetteville, AR). High temperatures negatively affect 'Concord' growth (Striegler et al, 2002). Although bud fruitfulness was physiologically established the previous season, the warmer temperature had a visible effect on 'Concord' vines, causing yellowing and scorching of leaves and delayed the time from veraison to harvest by about 2 weeks compared with 2004.…”

“…Outside of California, the primary red juice grape is 'Concord', which is produced in Washington, Michigan, New York, Pennsylvania, and Ohio. As an alternative, 'Sunbelt' (V. labruscana) can be grown where 'Concord' grapes display uneven fruit ripening associated with high temperatures (Moore et al, 1993;Morris et al, 2007, Striegler et al, 2002. Initial research indicated that 'Sunbelt' grown on a six-arm kniffen training system did not produce yields suitable for commercial production (Moore et al, 1993).…”

“…Initial research indicated that 'Sunbelt' grown on a six-arm kniffen training system did not produce yields suitable for commercial production (Moore et al, 1993). However, when grown on a double curtain training system, 'Sunbelt' produced commercially acceptable yield and quality in California and Arkansas (Morris et al, 2007;Striegler et al, 2002).…”