Height and number of shoots on the survival and development of micropropagated bamboo plantlets during pre-acclimatization

Abstract

ABSTRACT During the in vitro multiplication of bamboo plantlets, it is common the formation of shoots aggregates. Once individualized, these can yield a greater number of plantlets than if planted in clusters. This study aimed to evaluate the effect of the relationship between height and number of initial shoots in micropropagated bamboo plantlets on the survival and development of plants, during the pre-acclimatization stage. Guadua aff. chaparensis shoots, after successive subcultures of in vitro multiplication, were classified into three height classes (2.5-5.0 cm; 5.1-10.0 cm; 10.1-15.0 cm) and number of aggregate shoots (one shoot per plantlet/single-stem plantlet, two and three shoots per plantlet) and pre-acclimatized in a commercial substrate composition plus washed sand. The plantlets were evaluated for survival, height, number of new shoots and roots, shoot and root fresh and dry mass. In plantlets from micropropagation, the plant height does not influence the survival rates, being acclimatized preferably at heights between 5.0 cm and 15.0 cm, with survival rates of up to 97 %. Plantlets with height starting at 5.1 cm and composed of 2 or 3 initial shoots show a greater vigor and ex vitro growth, a fact evidenced by the higher values obtained in relation to height and emission of new shoots and roots, as well as a greater fresh and dry biomass accumulation.