The characterization of the bunch zone microclimate was assessed in vineyards with different aspect/ topography and vine vigor. The impact of bunch microclimate on the evolution of some relevant carotenoids during the ripening of Nebbiolo grapes cultivated in hilly Piedmont vineyards, was investigated.

Four bunch-zone microclimates, defined by different vineyard aspect and vine vigor, were characterized by radiation and temperature indices. Berry samples were collected from green phase up to harvest, during two consecutive seasons and carotenoid determination was assessed by High-Performance Liquid Chromatography (HPLC). Lutein and neoxanthin contents varied similarly in both seasons achieving a concentration peak after veraison especially in the cooler plots while a variety effect on the lutein seasonal trend was presumed. Conversely, β-carotene content remained generally constant during ripening, except for the south warm plots showing dissimilar evolution between the seasons.

Further knowledge was added about the influence that climate changes may have on grape aroma precursors such as carotenoids, and useful findings to adapt cultural strategies and preserve grape quality consequently. Higher temperature in the less vigorous and south facing vineyards led to lower amounts of carotenoids, both during ripening and at harvest. Bunch zone temperature and light condition may affect both synthesis and degradation of grape carotenoids determining their amount and profile at harvest.

Available at https://doi.org/10.3390/app10113846