Aplicação da citocinina na formação da semente sintética de jambu

Abstract

In the cultivation of jambu (Acmella oleracea), vegetative propagation is predominant because it presents better efficiency. Thus, the objective of this work was to evaluate different concentrations of cytokinin, BAP (6-benzylaminopurine), in the in vitro multiplication of nodal segments and in the production of synthetic seeds of jambu. The experiments were subdivided into two phases: For Exp. 1 were used as a source of explants nodal segments obtained from seeds germinated in vitro. Each nodal segment containing two axillary buds was inoculated in culture medium (MS) with 30 g L-1 of sucrose and added with five concentrations of BAP (0.000; 0.025; 0.050; 0.100 and 0.200 mg L-1), one for each treatment. Ten replicates were performed per treatment, with two nodal segments per flask. After 45 days, the treatments were evaluated for the number of leaves and number of shoots. Exp. 2, nodal segments originating from each of the concentrations of Exp. 1 were used as sources of explants for the production of synthetic seeds. Thus, five BAP treatments were evaluated in two containers (test tube and plastic pot). For this experiment, 18 repetitions were performed for the test tube (containing one synthetic seed per tube and in MS culture medium) and three repetitions for the plastic pot (containing six synthetic seeds per pot filled with substrate). After 30 days, they were evaluated for the number of leaves, number of shoots, stem diameter, fresh and dry mass of shoots and roots (g), hyperhydricity, conversion rate (%), and scanning electron microscopy of the adaxial leaf epidermis. The experimental design used for both experiments was completely randomized. Both were kept in a growth room at 25 ± 2°C and a 16-hour light photoperiod. Exp. 1, the concentration of 0.05 mg L-1 of BAP proved to be efficient in the multiplication and in obtaining jambu explants (mean of 94.5 leaves and 29.36 shoots per plant). Exp. 2, the concentration of 0.05 mg L-1 of BAP provided better conversion and development of synthetic seeds (95% conversion, 16 leaves and 3 shoots per plant) of jambu in a test tube. For plastic pots, there was a conversion of 26% of synthetic seeds in a non-sterile environment. It was concluded that the multiplication of jambu nodal segments in a medium enriched with 0.05 mg L-1 of BAP was efficient in obtaining explants, and for the conversion and development of synthetic seeds of jambu (Acmella oleracea).