Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines – The case study of malolactic fermentation

Context and purpose of the study. Rising temperatures and prolonged heat accelerate berry sugar accumulation in advance of the accumulation of compounds responsible for aroma, colour and mouthfeel.

The interaction between cultivar and growing environment is the base of wine quality and typicality. In recent time the behaviour of different clones within the same cultivar became another fundamental factor influencing the enological result. In order to clarify cultivar/clone/environment relations, a trial was carried out in 2008 studying the performances of three clones of ‘Nebbiolo’, grown in different environments: south-east Piedmont (hilly and characterized by a loamy and alkaline soil) and north-east Piedmont (a plain area characterized by a sandy and acidic soil).

Trichoderma is a microorganism present in many agricultural soils and some of its species could be used as natural biological control agents. In this work, the presence of natural populations of Trichoderma was estimated in soil vineyard and its biocontrol capacity against Phaeoacremonium minimum, one of the main agent causals of grapevine trunk diseases instead of using pesticides. Moreover, physicochemical variables in soil such as pH, organic matter and nutrients were evaluated to determine a possible correlation to natural populations of Trichoderma.

One of the most concerning trends associated with increasing heat and water stress is advanced ripening of grapes, which leads to harvesting fruit at higher sugar concentrations but lacking optimal phenolic (i.e. color and mouthfeel) and aromatic maturity. Mitigation techniques for this phenomenon have been studied for many years and practices to delay sugar accumulation have been identified, including antitranspirants, delayed pruning and late-source-limitation techniques. Evaluation of the efficacy of these vineyard practices has occurred across a wide range of environments, vintages, varieties and growing conditions. To assess the broader efficacy of these three vineyard practices, which are easy-to-implement and cost-effective, a meta-analytic approach was adopted using data retrieved from 43 original studies.

Today’s viticulture is facing a new climatic scenario with temperature increases and rainfall deficits, generated by the effect of climate change. As a result of these new conditions, there are earlier harvests, increased plant water stress and higher disease risk in wetter wine-growing regions.