Diversidade morfológica e propagação in vitro de gérberas a partir de folha peciolada.

Abstract

Gerbera is one of the most important cut flowers commercialized in the world, occupying the fifth place among the flowers in this ranking. The modern gerbera varieties present variety of colors and flower shapes due to genetic improvement, which began with the crossing two South African species, Gerbera jamesonii and Gerbera viridifolia, originating Gerbera hybrida. Micropropagation is the most common form of commercial propagation for this specie, because produces a large quantity of seedlings faster than natural. The objective of this research was to evaluate the diversity of gerbera genotypes based on morphological descriptors; establish a micropropagation of gerbera genotypes from the petiolate leaf and optimize the best hormonal balance auxin/cytokinin for the multiplication of gerbera genotypes. For both the diversity of assessment was made 14 gerberas arrays based on morphological descriptors leaves and flowers. Micropropagation of the genotypes was also carried out, with two experiments. In the first one was developed a micropropagation protocol, since: in vitro establishment used leaves with petiole as explant; on multiplication, diferente BAP (6-benzylaminopurine) and ANA (naphthalene acetic acid) concentrations were tested; in vitro rooting diferente ANA levels, sucrose concentrations and MS culture medium were tested, as well as the rooting of the genotypes in MS and B&G® media and acclimatization were analyzed. In the second micropropagation experiment, hormonal balance auxin/cytokine of the genotypes was optimized through different BAP and ANA concentrations. Considering the results, was observed the formation of four genotype groups when tested at Euclidian and Mahalanobis distance for quantitative data, and seven groups in Gower algorithm when the qualitative and quantitative data were analyzed jointly. The principal component analysis identified that the quantitative descriptor referring to the width of the ligated flower of the external radius which contributed least to the diversity. Differences were observed among genotypes for the number of shoots produced in vitro multiplication. On rooting was verified that the complete MS medium supplemented with 30 g L-1 sucrose and absence ANA, provided the obtaining bigger and better rooted seedlings. Was also observed that the B&G® culture medium provided better responses to rooting and seedling size and in the acclimatization, the genotype survival rate was high. Finally, hormonal balance evaluation indicated ideal BAP and ANA concentration for each gerbera genotype related to the number of shoots per explant and mean length of shoots. In this context, was possible to estimate the morphological diversity of the gerbera UFRRJ collection and establish a gerbera genotypes micropropagation protocol from the petiole leaf.