Genetic variability and predicted gain in progeny tests of native Atlantic Forest timber species: Cariniana legalis, Cordia trichotoma, and Zeyheria tuberculosa

Abstract

Over the years, the Atlantic Forest has been one of the biomes most affected by fragmentation and despite the scarcity of studies related to their genetic and breeding aspects, native Atlantic Forest species can provide various high-quality timber products. In this context, the objectives of this work were to estimate genetic parameters and predict genetic gain with selection of provenance/progeny tests of Cordia trichotoma, Zeyheria tuberculosa, and Cariniana legalis, for diameter at breast height (DBH) and survival rate. Seed trees from different provenances were selected and measured, and their seeds were collected and tested in the areas of Porto Seguro - Bahia state, Brazil. All test individuals were evaluated for DBH (cm) survival rate (%) and stem straightness. The variance components and genetic parameters were estimated for DBH and survival rate. The narrow-sense individual heritability (h2i) for DBH of the three species ranged from 0.26 to 0.72, showing moderate to high genetic control. However, based on the likelihood ratio test (LRT) there is no genetic variability among genotypes of Z. tuberculosa. For survival rate, high genetic control (0.54) was observed only for C. trichotoma, while for C. legalis and Z. tuberculosa h2i value was 0.11 and 0.0, respectively. After genetic parameter analyses, the expected genetic gains were estimated for seed trees, potential genitors and potential clones. For seed trees, gains based on the additive genetic values (u+a) for DBH by selecting the top 10 individuals of each species per family ranged between 17.17 and 30.31%. In the case of potential genitors, by selecting the top ten individuals based on u + a value, are expected gains between 19.17 and 49.65%. The ranking of the top ten potential clones based on genotypic values (u +g) for each species showed gains between 32.43 and 56.53%. Conducting genetic breeding for C. trichotoma and C. legalis presents high potential of genetic gains and efforts should be taken into account for supporting breeding strategies for those species. In the case of Z. tuberculosa, the absence of genetic variability seems to be a result of the Atlantic Forest deforestation and genetic basis narrowing.