INFLUENCE OF DIFFERENT ROOTSTOCKS ON THE VEGETATIVE AND REPRODUCTIVE PERFORMANCE OF VITIS VINIFERA L. MALBEC UNDER IRRIGATED CONDITIONS

Aims: A trial of cv. Malbec grafted to six different rootstocks (Harmony. SO4, 1103 P. 140 Ru, 3309 C and Cereza) and own rooted cv. Malbec (ORMa) was carried out with the aim to study the influence of rootstock on the vegetative and reproductive performance of cv. Malbec. Another objective was to study the relationship between below ground (i.e., rootstock) and above ground (i.e., scion) growth under irrigated conditions, typical of Argentine viticulture. Methods and results: Four groups of rootstocks could be distinguished according to their vegetative and reproductive performance. The first group (Cereza and 3309 C, as ORMa) showed intermediate yield and high vegetative expression (V E). The second group (SO4 and 1103 P) was characterized by high yield and intermediate VE. The third group (140 Ru) displayed intermediate yield and low YE. Finally, the fourth group (Harmony) showed low yield and low YE. 140 Ru showed the highest number of roots, while 1103 P. SO4 and Harmony showed the lowest number. Harmony showed a greater skin to berry ratio than 1103 P and a lower berry weight (1.56 g) than the rest of the treatments (1.7 g on average). Conclusion: Rootstocks influenced the biomass partitioning between leaves, grapes and roots: 140 Ru promoted root and reproductive development; Cereza. 3309 C and ORMa promoted vegetative development; SO4 and 1103 P promoted grape yield; and Harmony promoted root development. Significance and impact of the study: The absence of a general behavior pattern highlights the need to accurately assess the performance of each rootstock for each zone and each Vitis variety, in order to choose the most appropriate scion-rootstock combination.