WINETECH Technical Yearbook 2020

TABLE 1. Proportions of mean grape seed terminal subunits in 2010/2011 and 2011/2012 season. 2010/2011

Seed mDP varied between 2.7 and 8.8 in the 2010/2011 season and 2.9 and 7.7 in the 2011/2012 season during berry development among treatments (data not shown). In the 2011/2012 season, the respective treatments had higher amounts of extension subunits at the beginning of berry ripening than the 2010/2011 season, resulting in higher mDP (data not shown). The decrease of mDP and avMM from fruit set were observed. The percentage of galloylated derivatives was determined during both seasons (ta- ble 3). A significantly higher (p ≤ 0.001) percentage of galloylation was observed in the STD treatment when compared with the other three treatments in 2010/2011 (table 3). During the 2011/2012 season, no significant differences were observed be - tween the galloylation percentages among the treatments, suggesting that galloylation was influenced more by the season than the applied treatments (table 3). GRAPE SKIN COMPOSITIONAL CHANGES DURING RIPENING (+)-Catechin, (−)-epicatechin and (−)-epi - catechin-3-O-gallate were identified as the grape skin proanthocyanidin terminal sub- units (table 4). (+)-Catechin was the pre- dominant compositional contributor, with epicatechin and (−)-epicatechin-3-O-gal - late present in lower proportions or not detected (table 4). There was a significant

2011/2012

Treatment

C

EC

ECG 6.6 a 4.5 b 0.8 c 3.6 b

Treatment

C

EC

ECG 15.9 15.4 15.3 15.1

Standard (Control) Leaf Removal West

Standard (Control) Leaf Removal West LR (-UV-B, 2xOp50) LR (-UV-B, 2xUHI)

64.3 c 67.1 b 68.6 a 66.0 b

29.1 b 28.4 b 30.9 a 30.4 a

54.4 b 56.1 b 56.2 a 55.7 ab

29.6 a

28.5 ab 28.0 b 27.6 b

STD-UV-B LRW-UV-B Significance

*** ns Means in columns followed by a different letter are significantly different within one season. Percent composition of proanthocyanidin terminal seed subunits C, (+)-catechin; EC, (−)-epicatechin; ECG, (−)-epicatechin-3-O-gallate STD (Shaded/Control); LRW (Leaf Removal West); STD with decreased UV-B radiation (STD-UV-B); LRW with decreased UV-B radiation (LRW-UV-B); LR (-UV-B, 2xOp50)(Leaf removal with decreased UV-B radiation and 2xOp50 UV-sheets added on both sides of the bunch zone); LR (-UV-B, 2xUHI) (Leaf removal with decreased UV-B radiation and 2xUHI UV-sheets added on both sides of the bunch zone ). Significance (*, ** and *** indicate significance at p ≤ 0.05, 0.01, 0.001 respectively; ns: not significant). *** *** Significance *** ***

TABLE 2. Proportions of mean grape seed extension subunits in 2010/2011 and 2011/2012 season. 2010/2011

2011/2012

Treatment

C

EC

ECG 5.5 a 2.3 b 0.4 d 1.3 c

Treatment

C

EC

ECG

Standard (Control) Leaf Removal West

Standard (Control) Leaf Removal West LR (-UV-B, 2xOp50) LR (-UV-B, 2xUHI)

10.7 c 11.3 b 11.8 a 11.6 ab

83.8 c 86.4 b 88.2 a 87.1 b

10.8 bc 10.5 c 11.3 a 10.9 b

82.7 a 81.7 a 75.0 b 74.8 b

6.2 6.1 6.1 5.9

STD-UV-B LRW-UV-B Significance

Significance

***

***

***

***

***

ns

In the 2011/2012 season, the lowest av- erage polymer length was observed in the LR (-UV-B, 2xUHI) treatment, while the LR (-UV-B,-PAR) (shaded without leaves and laterals) treatment showed higher mDPs (table 6). The low mDP observed in

grape skins. Lower levels of (+)-catechin and (−)-epicatechin-3-O-gallate were found in both seasons (data not shown). In this study, light exposure did not have a significant impact on the extension unit composition in either of the seasons investigated.

difference (p ≤ 0.001) in the mean (+)-cat - echin and (−)-epicatechin-3-O-gallate ter - minal subunit contribution between the two seasons (table 5). (−)-Epigallocatechin was the predominant extension subunits followed by epicatechin in

WINETECH TECHNICAL YEARBOOK 2020 61