Evaluación de raíces en portainjertos serie Geneva ®

The rootstocks most used in apple production in Uruguay over the past decades (M.9 and M.7) are being replaced by Geneva series rootstocks. The latter were developed in the 1990s due to their resistance to pests and diseases, as well as their tolerance to replant conditions, among other positive characteristics.

In 2001, the National Institute of Agricultural Research (INIA) signed an evaluation agreement with Cornell University, leading to the introduction of these rootstocks to the country. A further introduction of new materials from the series followed in 2017. Despite the positive characteristics reported for this series, there is uncertainty regarding their agronomic performance both globally and nationally.

Root growth dynamics are one of the aspects that have been under-evaluated. This is the first study to characterize Geneva rootstocks using the mini-rhizotron method in the field.

In this study, six combinations of the Lady in Red variety with the most promising rootstocks of the Geneva series were evaluated through studies of root development, shoot growth, and fruit size. Evaluations were carried out in the fourth year after planting, during the 2022-2023 growing season at the INIA “Las Brujas” facilities in the department of Canelones. A randomized complete block design with three replicates of four trees each was used. Root measurement tubes with a scanner were installed in the central plant of each plot and shoot growth and fruit size variables were evaluated on one branch per tree, with three trees per replicate. The study year presented severe water deficit conditions, leading to an agricultural emergency declaration by the Ministry of Livestock, Agriculture, and Fisheries. During this cycle, no significant differences were observed between rootstocks in the evaluated root variables, except for root area at depth, where rootstock G.210 showed a greater root area at a greater depth. No significant differences were observed between the rootstocks in shoot growth; however, a trend toward greater overall growth was observed in rootstock G.213. Significant differences were found in fruit size, with rootstock G.213 differing from G.210.

We consider these data to be of great value when defining planting criteria such as planting pattern, density, and training systems. Further measurements should be taken in subsequent cycles to better understand the growth dynamics of the different root systems of these rootstocks.