Root Systems of Five Clonal Avocado Genotypes

The root system of clonal rootstocks has been poorly studied, despite its crucial importance. Roots not only provide support and nutrition to the plant but also contribute to tolerance to pests, diseases and environmental stresses, in addition to optimizing yields. Although the initial cost of clonal rootstocks is higher, the investment is offset by the reduction in phytosanitary treatments, greater longevity of the trees and a lower mortality rate. The aim of this research was to quantify the root system growth of five clonally propagated dwarf and normal avocado genotypes evaluated in rhizotrons, with the perspective of identifying distinctive characteristics suitable for their possible use in container culture. The avocado clonal plants to be evaluated were placed in rhizotrons and evaluated for six months, where 35 growth variables were evaluated with the aid of a root analyzer program. A randomized complete block design with five treatments (genotypes) and three replications was used under greenhouse conditions. Analysis of variance, variable purge and multivariate analysis were performed. It was found that ‘Duke 7’ and ‘San Martín’ were statistically different for most of variables, with ‘San Martín’ showing less root growth and ‘Duke 7’ showing remarkable lateral growth. The adventitious root system’s growth depends on the genotype, and the use of rhizotrons allows its study, which proved to be a useful methodology for this type of evaluation since it allows the visualization and adequate quantification of root growth. Genotypes with less root growth may be suitable for use in container culture, and roots with extensive lateral growth may be useful in shallow soils.