Sylvia Liggieri

MSc student, Viticulture

sylvia92@vt.edu

I am Silvia Liggieri, a graduate student currently in the second year of my Master of Science degree program. I graduated in 2014 from the University of Udine (Italy) in Viticulture and Enology, and worked in the wine industry since 2012, first in Italy then in the United States. In January 2017, I started my MSc program and the related research project in Viticulture under my advisor, Dr. Tony Wolf.

My research focuses on the grapevine responses to canopy management practices, in particular to fruit zone leaf thinning. The removal of leaves in the fruit zone can increase cluster exposure to sunlight and improve its microclimatic conditions. The effects of different timing and levels of application of fruit zone leaf thinning on grape quality are being evaluated on Chardonnay and Cabernet Sauvignon. Our goal is to reduce disease incidence and enhance grape composition, especially by increasing the accumulation of aroma compounds in harvested fruit.

To illustrate some of my work, Table 1 shows the results on some of the yield and quality parameters of the Chardonnay at harvest in 2017 as a function of the fruit zone treatments applied. The three fruit zone leaf thinning treatments significantly reduced both disease incidence and severity to a comparable extent. Table 2 shows the different impact of the treatments on some of the free volatiles aroma compounds on the same grapes, with the most intense treatment resulting in the highest concentration of TDN and b-damascenone. The aroma compounds analysis is done in collaboration with Dr. Misha Kwasniewski at the University of Missouri.

Table 1.

Effects of selective fruit zone leaf thinning on yield and sanitary status of Chardonnay at harvest

Treatment^a	Cluster/vine	Cluster weight (g)^b	Disease incidence % per vine^c	Overall severity % per vine^d
C	37.47 ab	105.82	4.87 a	1.07 a
PB	33.77 b	95.13	1.45 b	0.32 b
PF3	40.47 a	100.55	2.09 b	0.31 b
PF6	39.83 ab	117.27	0.79 b	0.08 b
Significance^e	p=0.0122	ns	p=0.0001	p<0.0001

^aC=control; PB=pre-bloom leaf removal; PF3=post-fruitset 3 leaves removed; PF6=post-fruitset 6 leaves removed.

^b Cluster weight is an average estimated by yield per vine/ number of cluster

^cDisease incidence is the % of rotted cluster per vine

^dOverall severity is the % of severity on rotted cluster * incidence per vine.

^eSignificance is set at 0.05 level, p>F. Comparison of means among treatments was made using Tukey-Kramer HSD test. Means not sharing the same letter are significantly different (

Table 2. Effects of selective fruit zone leaf thinning on free volatiles in Chardonnay at harvest in 2017.

Treatment^a	b-linalool µg/L	Nerol µg/L	TDN^b µg/L	b-damascenone µg/L
C	1.73	4.24	0.31 b	45.32 c
PB	2.32	3.76	0.42 b	50.48 bc
PF3	2.12	4.29	0.55 b	74.48 ab
PF6	2.43	2.42	1.12 a	82.19 a
Significance^b	ns	ns	p<0.0001	p=0.0025

^aC=control; PB=pre-bloom leaf removal; PF3=post-fruitset 3 leaves removed; PF6=post-fruitset 6 leaves removed.

^b1, 1, 5-Trimethyl-1, 2-dihydronaphthalene

^bSignificance is set at 0.05 level, p>F. Comparison of means among treatments was made using Tukey-Kramer HSD test. Means not sharing the same letter are significantly different (