Scion-rootstock interactions influence the growth and behaviour of the grapevine root system in a heavy clay soil

Background and Aims Generally, grapevine roots have been less studied than the above-ground parts of the plant. Here we analyse scion-rootstock interactions in mature vines growing in a heavy clay soil in a climate characterised by severe summer drought to investigate the effect of the scion-rootstock interaction in a suboptimal soil. Methods and Results The rootstocks, 34 Ecole de Montpellier, 140 Ruggeri and 1103 Paulsen, were grafted onto Nerello Mascalese and Nero d'Avola scions and assessed along with self-rooted vines. Root distribution and root architecture were analysed using the profile wall method at 0, 60 and 120 cm from the row midline. Root density was greatest at a depth between 21 and 60 cm. The cumulative root fraction for root density registered a beta value, a numerical quantity that summarises depth distribution, ranging between 0.932 and 0.962. Root number and density were significantly lower for the self-rooted vines compared to that of the grafted vines. Conclusions The scion genotypes affected most developmental parameters, including the diameter of the root system, the root density at 21-80 cm depth and the ratio of fine roots to coarse roots. Significance of the Study The scion plays an important role in grapevine root growth, development and distribution in a heavy clay soil, although the mechanism remains unclear.