Benefits and risks of the utilization of grape pomace as organic fertilizers

Several factors like vineyard site, climate, grape variety, ripeness, physical health of the grapes and pest management influence the populations of indigenous yeasts on grapes and later on in spontaneous fermentations.

Temperature has a decisive influence on the growth and development of plants (Carbonneau et al., 1992). In particular, in the case of the vine, the temperature is an omnipresent variable in the climatic indices (Huglin, 1986). For reasons of convenience, these indices use the temperature of the air measured under shelter in a meteorological station, making the implicit hypothesis of a concordance between this temperature and that of the sites of perception of the thermal stimulus by the plant. However, development may be more dependent on soil temperature than air temperature (Kliewer, 1975). Morlat (1989) thus verified that the variability in the precocity of the vine, positively correlated with the quality of the harvest and of the wine in the Loire Valley, was mainly explained by differences in temperature of the root zones.

Grape postharvest dehydration is a widely used technique for the special wines production, where genetic features, ripeness degree and environmental factors strongly influence the metabolic processes [1].

In most viticultural regions, grapevines are cultivated grafted, employing either hybrid or pure species of various American Vitis spp., such as V. berlandieri, V. rupestris, and V. riparia, as grapevine rootstocks. These rootstocks play a crucial role in providing resistance to the Phylloxera insect pest. Beyond Phylloxera resistance, it is desirable for grapevine rootstocks to exhibit resistance to other soil-borne pathogens and adaptability to abiotic stress conditions. The introduction of new rootstocks holds promise for adapting agriculture to climate change without altering the characteristics of the final harvested product.

In the current viticultural context, global warming leads to advanced and possibly accelerated ripening which can alter the balance among desirable grape quality traits sought for winemaking. Evaluation of genetic material that displays delayed and/or slower ripening could uncover a potential “slow ripening” trait for incorporation into commercial varieties through breeding. In this study, we evaluated a white-fruited selection discovered in the Grape Breeding and Genetics program at E. & J. Gallo Winery that displayed an unusual ripening pattern compared to standard varieties. Vines of the slow-ripening selection did not differ in their visual appearance, water status or gas exchange characteristics compared to vines of its normal-ripening sibling.