Chapter 22 - Adventitious root formation and clonal propagation of forest-based tree species

Abstract

Adventitious root (AR) formation is known to be a critical element in clonal propagation and germplasm conservation of important forest species, particularly those that are difficult to root. ARs have also been used for the generation of secondary metabolites, which are important bioactive molecules. For successful AR development, several external and internal elements work together. Ex vitro clonal propagation employing stem cuttings of forest tree species is a simple and effective method of AR formation that is known to lower production costs, save energy, and improve plantlet survival during hardening and field transfer. The tissue culture technique has also been used in achieving successful propagation of recalcitrant tree species through mass propagation of shoots and subsequent AR formation using auxins in suitable media. In all cases, the role of auxins, their type, and concentration used have been realized to be most significant for AR development in both field-based and laboratory-based strategies. Besides, the genotype, age, and endogenous hormone concentration of the mother plant impart a substantial effect on AR production. This chapter compiles information on effective strategies that have been employed for AR development in forest tree species, their role in tree propagation, and a variety of factors that drive AR development formation.