Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
Department of Biology, Faculty of Sciences, Ghent University, K L Ledeganckstraat 35, B-9000 Ghent, Belgium.
Tree Physiol. 2018 May 1;38(5):745-754. doi: 10.1093/treephys/tpx158.
Grapevines are characterized by a period of irreversible stem shrinkage around the onset of ripening of the grape berries. Since this shrinkage is unrelated to meteorological conditions or drought, it is often suggested that it is caused by the increased sink strength of the grape berries during this period. However, no studies so far have experimentally investigated the mechanisms underlying this irreversible stem shrinkage. We therefore combined continuous measurements of stem diameter variations and histology of potted 2-year-old grapevines (Vitis vinifera L. 'Boskoop Glory'). Sink strength was altered by pruning all grape clusters (treatment P), while non-pruned grapevines served as control (treatment C). Unexpectedly, our results showed irreversible post-veraison stem shrinkage in both treatments, suggesting that the shrinkage is not linked to grape berry sink strength. Anatomical analysis indicated that the shrinkage is the result of the formation of successive concentric periderm layers, and the subsequent dehydration and compression of the older bark tissues, an anatomical feature that is characteristic of Vitis stems. Stem shrinkage is hence unrelated to grape berry development, in contrast to what has been previously suggested.
葡萄藤的特征是在葡萄浆果成熟开始时，会出现一段不可逆的茎收缩期。由于这种收缩与气象条件或干旱无关，因此人们通常认为它是由于葡萄浆果在此期间的吸收能力增强所致。然而，迄今为止，还没有研究从实验上探讨这种不可逆茎收缩的机制。因此，我们结合了盆栽 2 年生葡萄藤（Vitis vinifera L. 'Boskoop Glory'）的连续茎直径变化测量和组织学研究。通过修剪所有葡萄串（处理 P）来改变吸收能力，而未修剪的葡萄藤作为对照（处理 C）。出乎意料的是，我们的结果表明，在两种处理中，都出现了葡萄转色后不可逆的茎收缩，这表明收缩与葡萄浆果的吸收能力无关。解剖分析表明，收缩是连续同心周皮层形成的结果，随后是较老的树皮组织的脱水和压缩，这是葡萄茎的一个解剖学特征。因此，与之前的观点相反，茎收缩与葡萄浆果的发育无关。
