Sexual and vegetative propagation and genetic diversity of Melanoxylon brauna ministumps
Name: ELBYA LEÃO GIBSON
Publication date: 26/02/2019
Examining board:
Name |
Role |
|---|---|
| TAÍS CRISTINA BASTOS SOARES | External Examiner * |
Summary: Melanoxylon brauna is a native tree species of the Atlantic Forest that has great potential for reforestation and urban afforestation. In face of the intense exploitation, it is on the list of endangered species of Brazilian flora in the category vulnerable, arousing interest in studies aimed at its conservation. This study aimed to characterize the genetic diversity of the ministumps of the mini-clonal hedge and to evaluate the propagation potential of M. brauna by means of cutting and minicutting techniques. The dissertation was structured in three chapters. In chapter I, the aim was to analyze the growth, quality and nutrition of M. brauna seedlings of two provenances cultivated in substrate supplemented with different doses of controlled release fertilizer. The seedlings were produced in 280 cm3 plastic tubes, in a randomized block design, with four replications, in a 2 x 4 factorial scheme, two provenances (Viçosa, MG and Linhares, ES) and four doses of the controlled release fertilizer (CRF) Basacote® Mini 6M: 0; 2.0; 4.0 and 8.0 g dm-3. After 120 days, the morphological quality of the seedlings was evaluated in order to select the two best doses of the CRF within each provenance. Considering that M. brauna presents difficulties in conventional vegetative propagating processes, the recommended dose of controlled release fertilizer is 8.00 kg m-3 for the seedlings from Linhares, ES aiming at the maximization of growth and production of seedlings and formation of the mini-clonal hedge. In chapter II, the aim was to evaluate the propagative potential of M. brauna, through cutting and minicutting techniques. It was selected 250 seedlings from Linhares - ES for the mini-clonal hedge formation, fertilized with the 8.0 g dm-3 of the CRF. These seedlings (ministumps) were transplanted to vases with a capacity of 7 L. At 30 days post-transplant, the ministumps were broken at the apical part to induce the emission of new shoots. Five collections of shoots were carried out to account for the productivity of ministumps. Shoots of ministumps were collected from the mini-clonal hedge for the minicutting rooting experiment, which was conducted in a completely randomized design (CRD), in a 2 x 4 factorial scheme, with four replications, with two types of minicuttings (apical and leaf shoots) and five concentrations of indolebutyric acid (IBA) (0, 2000, 4000, 6000 and 8000 mg kg-1) in plastic tubes of 55 cm3 filled with commercial substrate. Shoots were collected from the canopy of adult matrices at six years of age for the cutting rooting experiment, which was conducted in a completely randomized design (CRD), in a 2 x 4 factorial scheme, with four replications, with two types of minicuttings (apical and leaf shoots) and five concentrations of indolebutyric acid (IBA) (0, 2000, 4000, 6000 and 8000 mg kg-1) in plastic tubes of 55 cm3 filled with commercial substrate. The percentage of rooting, survival, length of the longest root, root surface area and root diameter were evaluated in rooted minicuttings. The data were submitted to analysis of variance, using the Tukey test at 5% of probability. The vegetative propagation of M. brauna by the minicutting technique is feasible from apical minicuttings of juvenile matrices treated with the doses 6000 and 8000 mg kg-1 of IBA. In chapter III, the aim was to evaluate the genetic diversity and structure in ministumps established in a mini-clonal hedge of M. brauna. For the genetic diversity of the ministumps, vegetative material was collected from 59 individuals, then 24 primers of the molecular marker ISSR were tested for selection of the most informative and subsequent DNA amplification by PCR. After obtaining the data, they were submitted to the analyzes. 11 primers were selected, which generated 183 fragments (63.93% of polymorphism). The polymorphic information content for each marker reached the mean value of 0.36, WHEREas the optimal number of ISSR locus was from 117 polymorphic fragments. High genetic diversity was found with the genetic diversity parameters by the Shannon (I = 0.545) and Nei (H = 0.366) indexes for the population sampling. In the graphical representation of the genetic distances eight groups were formed, one group with the majority of genotypes (47 genotypes), five groups with two genotypes and two groups with one genotype each. The results revealed high genetic diversity in M. brauna ministumps, determining the potential to be used as matrices for the collection of propagules in the production of seedlings.
Keywords: Asexual propagation, biodiversity conservation, Atlantic Forest, Forest species.
