Abstract The induction of polyploidy in Eucalyptus can lead to higher-yielding and more adapted clones, with better wood quality. After artificial polyploidization, it is necessary to certify the effectiveness of the process through cytogenetic analyses and anatomical trait evaluations. Thus, the aim of this study was to certify the chromosome duplication in artificially polyploidized clones of Eucalyptus grandis × Eucalyptus urophylla using cytogenetic analysis, flow cytometry, and leaf anatomy measurements. Chromosomal counts and DNA content estimation allowed the identification of artificially polyploidized clones and mixoploids. Polyploid clones had larger stomata diameter than diploids. The increase in stomata size was accompanied by lower stomatal density in most polyploid clones. The typical gigas effect of polyploidized plants was demonstrated by the expressive increase in leaf area in polyploid individuals compared to diploids. Our findings indicate that the use of polyploidy in Eucalyptus breeding is promising, allowing the discrimination of diploid, tetraploid, and mixoploid plants.

ABSTRACT Background: This review aims to discuss alternatives for obtaining new clones of eucalyptus ( Eucalyptus spp.) with greater efficiency than current methods, as well as the feasibility of obtaining hybrid seeds. The commercial-scale use of eucalyptus hybrid seeds may reduce implantation costs and bring other advantages for forest exploitation. The proposal focuses on using inbred progenies (S 1, S 2...S g) to improve the species. Self-fertilization releases a greater proportion of undesirable alleles hidden in heterozygotes, increasing selection success. Results: From the best individuals of the inbred progenies, full-sibling (FS) progenies will be developed, allowing the selection of new clones and conduct recurrent selection programs. The hybrid seeds must be obtained, also from the FS evaluations, in each selfing generation (S g x S g). Simultaneously with the conduction of inbreeding generations, information must be gathered aiming to implement the strategy for obtaining hybrid seeds, such as verifying the feasibility of generating double haploid lines and looking for alternatives to facilitate the large-scale production of hybrid seeds. Conclusion: this review of research results can serve as an initial basis for obtaining new clones of eucalyptus with greater efficiency than current methods, as well as the feasibility of obtaining hybrid seeds.

RESUMO A exploração florestal é conduzida em milhares de hectares e apresenta ampla variação nas condições ambientais em termos de solo, clima e até mesmo manejo, assim, identificar clones que possam ser recomendados para essas diversas condições é um grande desafio. Nesta recomendação, um caráter importante é o incremento médio anual em celulose (IMACEL). Este estudo teve como objetivo avaliar a interação de diferentes clones e ambientes para o IMACEL com a finalidade de verificar se a origem da seleção dos clones afeta seu desempenho em outras regiões e identificar clones com base na adaptabilidade. Foram utilizados dados de IMACEL referente à avaliação de clones de Eucalyptus da empresa Suzano S.A. em cinco ambientes, nos estados do Espírito Santo, São Paulo e Mato Grosso do Sul. Os testes clonais foram instalados no delineamento de blocos casualizados com parcelas de uma planta. Dados referentes ao IMACEL das árvores, aos cinco anos, foram submetidos à análise de variância por ambiente e, posteriormente, à análise conjunta. A interação clones x ambientes foi expressiva para o IMACEL, porém, a origem de seleção dos clones não afeta o seu desempenho quando utilizados em outras regiões. Alguns clones se destacaram quanto à adaptabilidade, permitindo maior segurança à empresa na recomendação para diferentes ambientes.

ABSTRACT Forest exploitation is conducted in thousands of hectares in Brazil and presents a wide variation in environmental conditions in terms of soil, climate and even management, so identifying clones that may be recommended for these various conditions is a major challenge. In this recommendation, one important character is the mean annual increment in cellulose (MAICEL). This study aimed to evaluate the interaction of different clones and environments for MAICEL in order to verify whether the origin of clone selection affects their performance in other regions and to identify clones based on adaptability. MAICEL data were used for the evaluation of clones from Suzano S.A. in five environments distributed in the states of Espírito Santo, São Paulo, and Mato Grosso do Sul. Clonal tests were arranged in a randomized block design with plots of one plant. Data on MAICEL of the trees at five years were submitted to analysis of variance per environment and, subsequently, to the joint analysis. The clones x environments interaction was expressive for MAICEL, however, the origin of selection does not affect the performance of clones when grown in other regions. Some clones stood out for their adaptability, allowing more security to the company on the recommendation for different environments.