Chilling requirements and dormancy evolution in grapevine buds

ABSTRACT Fluctuations in winter chilling availability impact bud dormancy and budburst. The objective of this work was to determine chilling requirements to induce and overcome endodormancy (dormancy controlled by chilling) of buds in different grape cultivars. ‘Chardonnay’, ‘Merlot’ and ‘Cabernet Sauvignon’ shoots were collected in Veranópolis-RS vineyards in 2010, and submitted to a constant 3 °C temperature or daily cycles of 3/15 °C for 12/12h or 18/6h, until reaching 1120 chilling hours (CH, sum of hours with temperature ≤ 7.2 °C). Periodically, part of the samples in each treatment was transferred to 25 °C for budburst evaluation (green tip). Chilling requirements to induce and overcome endodormancy vary among cultivars, reaching a total of 136 CH for ‘Chardonnay’, 298 CH for ‘Merlot’ and 392 CH for ‘Cabernet Sauvignon’. Of these, approximately 39, 53 and 91 CH are required for induction of endodormancy in the three cultivars, respectively. The thermal regimes tested (constant or alternating) do not influence the response pattern of each cultivar to cold, with 15 °C being inert in the CH accumulation process. In addition, time required to start budburst reduces with the increase in CH, at a rate of one day per 62 CH, without significant impacts on budburst uniformity.

摘要：冬季低温累积时长的波动会影响芽休眠与芽萌发过程。本研究旨在明确不同葡萄品种的芽内休眠（endodormancy，由低温调控的休眠状态）诱导与解除所需的需冷量。研究于2010年在巴西韦拉诺波利斯-南里奥格兰德州的葡萄园采集霞多丽（Chardonnay）、梅洛（Merlot）与赤霞珠（Cabernet Sauvignon）的枝条，将其分别置于3℃恒温环境，或每日12/12小时、18/6小时的3/15℃变温环境中，直至累积达到1120需冷小时（CH，即温度≤7.2℃的小时数总和）。定期将各处理组的部分样品转移至25℃环境中开展芽萌发评价，以露绿尖作为判定标准。不同葡萄品种诱导和解除内休眠所需的需冷量存在显著差异：霞多丽总计需136 CH，梅洛为298 CH，赤霞珠为392 CH。其中，三个品种诱导内休眠分别仅需约39、53和91 CH。本次试验设置的温度处理模式（恒温或变温）并未影响各品种对低温的响应模式，15℃不会参与需冷量的累积过程。此外，芽萌发起始所需时长随CH累积量的增加而缩短，缩短速率为每62 CH缩短1天，且对芽萌发整齐度无显著影响。