Optimization of Factors Influencing Adventitious Rooting in Hybrid Larch

Abstract

Optimization of in vitro adventitious root induction contributes to the development of a large-scale production system of hybrid clone seedlings of larch (Larix spp.). We used orthogonal testing to investigate the factors that affect the rooting of hybrid larch shoots–activated carbon, vitamin B1, sucrose, glycine, glutamic acid (Glu), cysteine, pH, and induction time in the dark and indole-3-butyric acid (IBA). Variance analysis showed that the effects of sucrose concentration on rooting rate, survival rate, and average root number, pH on the average number of roots; and Glu on survival rate were all significant (p < 0.05) when compared to the mock treatments. Among all of the 45 treatments, the highest rooting rate was 90%, the highest survival rate was 100%, and the highest average root number was 11.8. The theoretically optimal procedure of in vitro root induction of hybrid larch shoots is shoot induction on L9 modified medium (pH 6.7) containing 2 mg.L–1 naphthalene acetic acid, 0.25 mg.L–1 IBA, 1/3 macroelements, 7.5 g.L–1 sucrose, and 5 mg.L–1 Glu for 8 days, and then root induction on L9 modified medium without auxin.