REDWINE project: use of Chlorella vulgaris to prevent biotic and abiotic stress in Palmela’s region, Portugal, vineyards

Context and purpose of the study. Vitis vinifera grapevine is a perennial crop which is globally cultivated, surviving cold winters in temperate zones by entering a state of dormancy.

In the context of sustainable viticulture that implements organic practices to maintain soil fertility, green manuring plays a crucial role due to its ability to stock carbon and nitrogen in soil while supporting biodiversity.

The European Landscape Convention (ELC, 2001) defined the landscape as the “part of a
territory as perceived by the population and resulting from the action of natural and/or human factors and their interrelationships”. Wine landscapes, protected or not under figures such as cultural landscapes or Cultural heritage, are a clear demonstration of this definition, denoting the interrelationships of the natural
environment and the action of the human, which modulates the territory to give the different wine
landscapes. This work was focused on the study of the effect of the human factors linked to the cultivation of the vine on the modification of the landscape.

During alcoholic fermentation, nitrogen is one of essential nutrient for yeast as it plays a key role in sugar transport and biosynthesis of and wine aromatic compounds (thiols, esters, higher alcohols). The main issue of a lack in yeast assimilable nitrogen (YAN) in winemaking is sluggish or stuck fermentations promoting the growth of alteration species and leads to economic losses. Currently, grape musts are often characterized by low YAN concentration and an increase of sugars concentration due to global warming, making alcoholic fermentations even more difficult. YAN depletion can be corrected by addition of inorganic (ammonia) or organic (yeast derivatives products) nitrogen during alcoholic fermentation.

One of the main aspects of Climate Change is the increase of temperatures during summer and grape maturity period. Physiological processes are influenced by these high temperatures and result in grapes with higher sugar concentration, less acidity and less anthocyanin content among other quality changes. One strategy to deal with the climate change effects is the implementation of late winter pruning to alter the effect of high temperatures during key periods by delays in maturity time.