RESUMO
Introduction: The increase of temperature due to climate change at different phenological stages of grapevine has already been demonstrated to affect accumulation of primary and secondary metabolites in grape berries. This has a significant implication for Pinot noir especially in New Zealand context as these compounds can have direct and indirect effects on wine quality. Methods: This study investigates how varying bunch microclimate through changes in temperature applied at veraison stage can affect: fresh weight, total soluble solids, the accumulation of anthocyanins, total phenolics and amino acids of the grape berries. This was studied over two growing seasons (2018/19 and 2019/20) with Pinot noir vines being grown at two different temperatures in controlled environment (CE) chambers. The vines were exposed to 800 µmol/m2/s irradiance with diurnal changes in day (22°C or 30°C) and night (15°C) temperatures. This experimental set up enabled us to determine the accumulation of these metabolite at harvest (both seasons) and throughout berry development (second season). Results and discussion: The results showed that berry weight was not influenced by temperature increase. The total soluble solids (TSS) were significantly increased at 30°C, however, this was not at the expense of berry weight (i.e., water loss). Anthocyanin content was reduced at higher temperature in the first season but there was no change in phenolic content in response to temperature treatments in either season. The concentrations of total amino acids at harvest increased in response to the higher temperature in the second season only. In addition, in the time course analysis of the second season, the accumulation of amino acids was increased at mid-ripening and ripening stage with the increased temperature. Significant qualitative changes in amino acid composition specifically the α-ketoglutarate family (i.e., glutamine, arginine, and proline) were found between the two temperatures. Significance: This study is the first to provide detailed analysis and quantification of individual amino acids and phenolics in Pinot noir in response to changes in temperature applied at veraison which could aid to develop adaptation strategies for viticulture in the future.
RESUMO
Climate change has already been affecting the regional suitability of grapevines with significant advances in phenology being observed globally in the last few decades. This has significant implications for New Zealand, where the wine industry represents a major share of the horticultural industry revenue. We modeled key crop phenological stages to better understand temporal and spatial shifts in three important regions of New Zealand (Marlborough, Hawke's Bay, Central Otago) for three dominant cultivars (Merlot, Pinot noir, and Sauvignon blanc) and one potential new and later ripening cultivar (Grenache). Simulations show an overall advance in flowering, véraison, and sugar ripeness by mid-century with more pronounced advance by the end of the century. Results show the magnitude of changes depends on the combination of greenhouse gas emission pathway, grape cultivar, and region. By mid-century, in the Marlborough region for instance, the four cultivars would flower 3 to 7 days earlier and reach sugar ripeness 7 to 15 days earlier depending on the greenhouse gas emission pathway. For growers to maintain the same timing of key phenological stages would require shifting planting of cultivars to more Southern parts of the country or implement adaptation strategies. Results also show the compression of time between flowering and véraison for all three dominant cultivars is due to a proportionally greater advance in véraison, particularly for Merlot in the Hawke's Bay and Pinot noir in Central Otago. Cross-regional analysis also raises the likelihood of the different regional cultivars ripening within a smaller window of time, complicating harvesting schedules across the country. However, considering New Zealand primarily accommodates cool climate viticulture cultivars, our results suggest that late ripening cultivars or extended ripening window in cooler regions may be advantageous in the face of climate change. These insights can inform New Zealand winegrowers with climate change adaptation options for their cultivar choices.