Genetic Variability for Clonal Propagation of Acacia mearnsii

Abstract

Plantations of Acacia mearnsii established from seeds often exhibit low levels of productivity due to significant differences in plant growth. Therefore, the aim of this study was to assess the genetic control associated with clonal propagation of A. mearnsii and use a selection index to quantify gains for traits related to vegetative propagation. Data collected from nurseries for 2 years included mini-cutting productivity per mini-stump (PD), percentage of adventitious rooting (ENR), and ramet productivity index (PI). For clone production traits, PD (r = 0.36) and PI (r = 0.24) demonstrated moderate repeatability, whereas ENR (r = 0.06) exhibited low repeatability. Tree height (H2 = 0.20), and diameter at breast height (H2 = 0.13) showed moderate and low heritability, respectively. Genotype selection for vegetative propagation supported by PI-generated selection gains of over 50%, suggesting the efficacy of using this criterion in early evaluation and selection of genotypes for nursery propagation. The additive selection index considering PI and Ht traits can be used for early selection of superior A. mearnsii genotypes, promoting estimated gains of up to 2.5%. Given the importance of these parameters, these findings provide crucial insights for A. mearnsii breeders, addressing a notable gap in the literature concerning these traits. Study Implications: The moderate heritability of traits such as mini-cutting productivity, propagule productivity index (PI), height, and diameter at breast height, except for the percentage of adventitious rooting, which showed low heritability, suggests that these traits are influenced by genetic factors to a considerable extent. The study suggests that the selection of genotypes based on PI can significantly improve vegetative propagation outcomes, with potential selection gains of more than 50%. This indicates that nurseries can achieve higher productivity and efficiency by implementing genotype selection processes based on this criterion.