A new medium formulation for in vitro rooting of carob tree based on leaf macronutrients concentrations

Abstract

Experiments were performed to optimize the macronutrients concentrations for in vitro rooting of Ceratonia siliqua micropropagated shoots. Several dilutions of Murashige and Skoog (MS) medium were tested: full-strength MS, halfstrength MS (½MS), and ½MS + full N. The frequency of in vitro rooting was enhanced when the ½MS was used (50 % rooted shoots). Mature leaves from 20 - 30 year-old carob trees and from 2 year-old micropropagated plants were collected and the concentrations of macronutrients (N, P, K, Ca, Mg) assessed. Based on the mineral composition of the leaves a new medium was formulated and compared with the previous ones showing an increment of the rooting frequency to 80 %. Moreover, shoots rooted in the new medium did not show symptoms of apical necrosis that occurred in the other tested media.