The impact of global warming on Ontario’s icewine industry

The use of the term bioprotection in winemaking refers to the use of non-chemical methods to prevent the development of undesirable microorganisms (yeasts and/or bacteria). The reason for studying this method is mainly as a natural alternative to the addition of sulfites during the pre-fermentation stages. In winemaking, the addition of s02 has multiple functions, the main ones being antiseptic and antioxidant power.

The Ribera del Duero Designation of Origin (DO) has acquired great recognition during the last decades, being considered one of the highest quality wine producing regions in the world. This DO has grown from 6,460 ha of vineyards officially registered in 1985 to approximately 21,500 ha in 2013. The total grape production stands at around 90 million kg, with an average yield that approaches nearly 4,500 kg/ha. Most vineyards are cultivated under rainfed conditions.

The ’Furmint’ is the most important grape variety in the Tokaj Wine Region, constituting around 65% of its vineyard area. Before the phylloxera disease many types were grown, but as selection started in the 20th century, its diversity dramatically narrowed. As a result, the cultivation of Furmint was based mainly on two heavy-cropping clones, T.85 and T.92 at the end of the ’80s. Aims of present clone research take into account that after solely quantity as target, quality emerged in the 1990’s and most recently, typicity appeared as more private estates began their own selection program.

Copper is listed among the active substances candidates for substitution (Regulation EU 2015/408). Yet still, because of the lack of valid alternatives, the European Commission recently confirmed its usage authorization by limiting the maximum amount to 28 Kg per hectare in 7 years, i.e. an average of 4 kg/year (Reg. EU 2018/1981).This restriction is due to copper accumulation in soils and surface waters both caused by a steady application, especially on perennial crops (Riepert et al., 2013). The aim of this work is to determine if treatments with reduced copper dosages are able to reach different grapevine’s organs, with particular focus on the core of bunches, and if these small amounts can ensure the respect of the legislative prescription, without compromising the phytosanitary conditions of the vineyards, thus grape yields.

The favorable effect of symbiosis with arbuscular mycorrhizal fungi (AMF) has been known and studied since the 60s. Nowadays, many companies took the chance to start promoting and selling commercial inoculants of AMF, in order to be used as biofertilizers and encourage sustainable biological agriculture. However, the positive effect of these commercial biofertilizers on plant growth is not always demonstrated, especially under field conditions. In this study, we used a commercial inoculum on newly planted grapevines of a local cultivar grafted on a common rootstock R110. We followed the physiological status of vines, growth and productivity and functional biodiversity of soil bacteria during the first and second years of 20 inoculated with commercial inoculum bases on Rhizophagus irregularis and Funeliformis mosseaeAMF at field planting time and 20 non-inoculated control plants. All the parameters measured showed a neutral to negative effect on plant growth and production. The inoculated plants always presented lower values of photosynthesis, growth and grape production, although in some cases the differences did not reach statistical significance. On the contrary, the inoculation supposed an increase of the bacterial functional diversity, although the differences were not statistically significant either. Several studies show that the effect of inoculation with AMF is context-dependent. The non-favorable effects are probably due to inoculation ineffectiveness under complex field conditions and/or that, under certain conditions, AMF presence may be a parasitic association. This puts into question the effectiveness of its application in the field. Therefore, it is recommended to only resort to this type of biofertilizer when the cultivation conditions require it (e.g., very low previous microbial diversity, foreseeable stress due to drought, salinity, or lack of nutrients) and not as a general fertilization practice.