WINETECH Technical Yearbook 2020

the major acylated anthocyanin in all treatments in both seasons (data not shown). The individual anthocyanin com- position in 2010/2011 was not significantly different for most of the anthocyanins among treatments. However, in 2011/2012 significant differences were observed in all the derivatives except for petunidin coumaroyl-glucoside. This indicates that the higher temperatures experienced in 2010/2011 had a larger impact rather than PAR. This also resulted in similar con- centrations and contents of antho- cyanins in the STD and LRW treatments in 2010/2011 and 2011/2012, respect ively. The second season (2011/2012) was cooler, resulting in shifts in the anthocyanin profiles, confirming the findings of other authors who found vintage effects to play an important role in anthocyanin composition (Crippen & Morrison, 1986; Gao & Cahoon, 1994). From these results there was not a clear trend in anthocyanin accumulation in grape related to a different light exposure. Inconsistent treatment effects indicated that seasonal (climatic) impact was greater than any impact due to treatment.

light exposure in addition to UV-B exclusion. Conflicting treatment results indicate that the season had a significant impact. Overall, there was no significant difference in the anthocyanin concentration and content in both the STD and LRW treatments for both seasons (table 1). The mean anthocyanin concentration and content of the STD-UV-B and LRW-UV-B treatments in 2010/2011 were also similar (table 1). COMPOSITION Mono-glucosides, acetyl-glucoside and coumaroyl-glucoside derivatives of delphinidin, petunidin, peonidin and malvidin were determined in both seasons (data not shown). The accumulation of the individual anthocyanins commenced at véraison, at 48 DAA and 68 DAA, in 2010/2011 and 2011/2012, respectively, which is in agreement with the findings of other researchers (Ryan & Revilla, 2003; Downey et al. , 2006; Mori et al. , 2007). In the total anthocyanin pool, mono- glucoside was the predominant form, while acetyl-glucoside and coumaroyl-glucoside forms were present in lower proportions (data not shown). Malvidin-3-O-glucoside was the dominant anthocyanin and malvidin-3-O-acetyl glucoside was

0,30

3,00

STD STD-UV-B LRW LRW-UV-B

B

A

STD STD-UV-B LRW LRW-UV-B

0,25

2,50

0,20

2,00

0,15

1,50

0,10

1,00

0,05

0,50

Anthocyanin content (mg/berry)

0,00

0,00 Anthocyanin concentration (mg/g skin)

48

62

76

90

116

48

62

76

90

116

DAA

DAA

3,00

STD LRW

0,30

C

STD LRW

D

LR (-UV-B,2xOp50) LR (-UV-B,2xUHI)

2,50

0,25

LR (-UV-B,2xOp50) LR (-UV-B,2xUHI)

2,00

0,20

0,15

1,50

0,10

1,00

0,05

0,50

Anthocyanin concentration (mg/g skin)

Anthocyanin content (mg/berry)

0,00

0,00

68

82

96

110

130

68

82

96

110

130

DAA

DAA

FIGURE 2. Developmental changes in the skin anthocyanin concentration expressed as mg/g fresh skin weight and content (mg/berry) during berry development under different light conditions: (a) 2010/2011 anthocyanin concentration, (b) 2010/2011 anthocyanin content, (c) 2011/2012 anthocyanin concentration, and (d) 2011/2012 anthocyanin content. Each value represents the mean of five replicates ± standard error.

WINETECH TECHNICAL YEARBOOK 2020 67