Propagação de Luehea divaricata Mart. & Zucc. e análise da estrutura genética de fragmentos naturais com marcadores microssatélites

Abstract

Luehea divaricata Mart. & Zucc. is a native forest species of the Atlantic Forest, popularly known as açoita-cavalo and member of the Malvaceae family. The natural populations of Luehea divaricata and many other native species have been drastically reduced due to intense exploration of the Atlantic Forest, making it increasingly difficult to find suitable specimens for commercial and ecological use. By the way, many difficulties are found to obtain viable seeds, with appropriate physiological and sanitary characteristics, making it difficult to produce seedlings by sexual via. For this reason, is extremely important to evaluate the quality of seed lots, and seeing the difficulties in reproducing the species via seminal, micropropagation and minicutting may be alternatives to overcome the difficulties in its multiplication. The present work aimed to evaluate methodologies related to the vegetative propagation of Luehea divaricata, in order to simultaneously support the production of seedlings and the conservation of genetic resources of this native Brazilian forest species. With regard to seed quality, the results corroborate their orthodox physiological behavior in storage, and indicate that it is possible to maintain their viability even after long periods of storage in the refrigerator, in the specific case, for four years. For micropropagation, 10 or 20 μM IBA are efficient to root shoots at 60 days of in vitro cultivation. In the experiment related to minimal growth and subsequent growth resumption, 10 g L-1 sorbitol is efficient for in vitro conservation, which can be performed for up to 120 days. However, the subsequent resumption of shoot growth is limited to a 90 days storage period in the presence of sorbitol. In the minicutting, at 30 days of cultivation, 1000 mg L-1 of IBA in “pulse” treatment produces satisfactory results regarding the formation and number of roots, saving time and costs. The productivity of the miniceps is higher in summer, when the seedlings develop and root better, but can be collected in other seasons, indicating that the minicutting process can continue throughout the year, under the conditions evaluated. Genetic variability is greater within (77%) of the three natural fragments, which is expected to occur in species that reproduce predominantly by crosses. The results obtained are fundamental for the proper choice of management strategies and genetic conservation of these forest resources.