Stomatal restrictions to photosynthesis in grapevine cultivars grown in a semiarid environment

Leaf removal in the fruit-zone has been employed to improve cluster light exposure and ventilation and therefore increase metabolite accumulation and reduce botrytis incidence in berries. When applied before flowering (early defoliation – ED), it can also decrease cluster compactness and regulate yield in high-yielding varieties. This study aimed to evaluate the impact of ED on the physiology and metabolism of Aragonez (syn. Tempranillo) berries along the ripening period. The experiment was set up in 2013 at a commercial vineyard located in the Lisbon winegrowing region.

Certain yeast species belonging to the Pichia genus are known to form a distinctive film on grape must and wine. In a mixed-culture type fermentation, Pichia spp. (P. kluyveri in particular) are known to impart beneficial oenological attributes. In this study, we report on an easy isolation method of Pichia spp. from grape must by exploiting their film-forming capacity on media containing 10% ethanol. We isolated and identified two Pichia species, namely Pichia kudriavzevii and Pichia kluyveri, and subsequently co-inoculated them with Saccharomyces cerevisiae to ferment Gewürztraminer musts. Noteworthy differences included a significant increase in the 2-phenethyl acetate levels with the P. kluyveri co-fermentation and a general increase in ethyl esters with the P. kudriavzevii co-fermentation. Both Pichia co-inoculations yielded higher levels of glycerol in the final wines. Based on all the wine parameters we tested, the P. kluyveri strain that was isolated performed similarly to a commercial P. kluyveri strain.

The Maule region hosts up to a third of the total area of vineyards in Chile, in an environment where ancient practices inherited from the colonial past coexist with modernity and dynamism that include technified irrigation and fine vines. In the dry land of Maule there is a viticulture that has subsisted with ancient vines and traditions transmitted over generations, and there is little clarity about the origin and classification of the Maule viticulture, giving rise to the use of different concepts as synonyms to describe the ancient, minority, patrimonial or Criollas vines. In order to characterize and protect the ancient material, we studied the genetic diversity of a territorial collection that covers 80% of the communes of the region, prioritizing plants established more than 40-60 years ago.

The reflectance spectra of vegetation carry potentially useful information that can be used to determine chemical composition and discriminate between vegetation classes. If compared with analytical methods such as conventional chemical analysis, reflectance measurement provides non-destructive, economic, near real-time data. 

The increase in temperature caused by climate change produces an earlier budbreak date that affects the vineyard, which generates a greater risk of damage by spring frosts.