Effects of Water Stress, Defoliation and Crop Thinning on Vitis vinifera L. cv. Solaris: Part I: Plant Responses, Fruit Development and Fruit Quality

Abstract

Viticultural practices and irrigation have a major impact on fruit development and yield, and ultimately on must quality. The effects of water deficit (WD), defoliation (Def), and crop-thinning (CT) on Solaris plants and fruit development, as well as on the chemical composition of grape juice were investigated. WD was induced at three periods during fruit development (pre-veraison, veraison, and ripening) in pot-grown plants, while Def and CT were carried out on field-grown plants. Environmental and vegetative parameters were monitored during the experiments. The bulk chemical composition of the fruits was determined in juice by Fourier Transform-Infrared (FT-IR) spectroscopy throughout fruit ripening and at final harvest. The results showed that WD reduced soil water content and leaf water status. CT significantly reduced yield per vine, but increased cluster size. Mid to late WD reduced soluble solids by 1%. CT increased sugar content in juice, while Def decreased sugar accumulation. Total acids were higher in the juice from the field vines. Yet, CT lowered malic and tartaric acids. Def increased tartaric acid. Ammonia and alpha amino nitrogen were higher in the juice from pot-grown vines, while pH was lowered by Def and raised by CT. It is concluded that Solaris has a remarkable ability to tolerate and recover from WD. CT and Def significantly affected the bulk chemical composition of grapes in terms of total acidity and sugar accumulation, with CT grapes having the highest sugar content and the lowest total acidity and Def the opposite.

Effects of Water Stress, Defoliation and Crop Thinning on Vitis vinifera L. cv. Solaris Must and Wine Part II: 1H NMR Metabolomics

“…In this study, 1 H NMR metabolomics was employed to investigate the impact of different viticultural practices, including defoliation (DEF), crop thinning (CT), and irrigation (WD) on the chemical composition of must and wine samples from the cool-climate grape variety Solaris. The metabolomics investigation presented here complements our previously published study [ 3 ] by describing (1) the baseline metabolome of must and wines as a function of different growing conditions, (2) the changes in the bulk metabolome of must and wine samples obtained from different viticultural treatments, and (3) the changes in the bulk metabolome of must and wine samples from vines that underwent water deficit.…”

“…Must and wine samples were also analyzed by FT-IR spectroscopy. The reader is referred to Aru et al (2022) for more details on the FT-IR measurements of must samples [ 3 ]. WineScan analysis of the WD wines showed no significant differences for all parameters except for malic acid, which was significantly lowered by early- and mid-stress ( Table S1 ).…”

“…Malate is one of the prevalent acids in grapes. Unlike tartrate, the content of malic acid and citric acid is known to decline over the course of the growing season [ 46 ], which in this experiment occurred earlier in the screenhouse vines due to the higher temperatures [ 3 ]. Grapes grown in cool regions often contain higher concentrations of acids, which may result in tart wines.…”

“…Solaris is a relatively new cultivar of Vitis vinifera (L.), and for this reason, the number of investigations targeting viticultural and oenological aspects related to this white grape variety is quite limited ( Table 1 ). Solaris is a hardy grapevine that thrives in cold climates, with a good resistance to downy mildew, and that, from an agronomical point of view, has a remarkable ability to tolerate and recover from short-term water deficit [ 1 , 2 , 3 , 4 ].…”

Comparing a New Non-Invasive Vineyard Yield Estimation Approach Based on Image Analysis with Manual Sample-Based Methods

“…The capacity to accurately estimate the yield of a vineyard in the early stages of development can be extremely advantageous for the winegrower, with impacts on the whole vine and wine production chain. In the vineyard, it can help plan strategies of grape thinning as a yield regulation practice or to plan harvest in terms of logistics, scheduling, workforce and machinery requirements [1,2]. In the cellar, it helps planning for tank space allocation, crusher intake scheduling and oenological products.…”