Water stress and rootstock influence on leaf gas exchange of grafted and ungrafted grapevines

Abstract

In order to investigate the effects of rootstocks on plants of the genus Vitis subjected to gradually increased levels of water stress we studied the links between abscisic acid in leaves and the major leaf physiological parameters. Cuttings of Vitis vinifera cv. Müller Thurgau were grafted onto three hybrid rootstocks (H1, H8, H26) and grown in pots. Own-rooted plants of V. vinifera and own-rooted hybrids were also cultivated in an identical manner. Vines were tested during 7 and 14 days of water stress (i.e. daily water supply reduced to 66% of well-watered plants). Water stress reduced net photosynthesis and stomatal conductance with large differences between grafted and ungrafted vines. Significant differences were observed after only 14 days of water stress. In particular two grafting combinations, V. vinifera grafted on H1 (V/H1) and H8 (V/H8), did not show net photosynthesis reduction after 14 days of water stress. Water use efficiency increased with water stress whereas carboxylation efficiency was reduced. Net photosynthesis, stomatal conductance and carboxylation efficiency were affected by the rootstock genotype combination, so that under water stress only some rootstock genotypes transferred drought tolerance to the scion. Abscisic acid in leaves increased significantly from Control to 7 and 14 days of water stress but the relations with CO 2 assimilation rate, stomatal conductance and carboxylation efficiency appeared to be affected by the genotype of the vegetative apparatus. Our data show that the interaction between scion and rootstock with regard to production performance under water deficits may be an important consideration in vineyard planting strategies.