?rea de concentra??o: Biotecnologia e melhoramento gen?tico florestal. / Incluir a Companhia Energ?tica de Minas Gerais S.A. (CEMIG), Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) e Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) como ag?ncias financiadoras. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-12-18T17:15:46Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lilian_almeida_brito.pdf: 1387334 bytes, checksum: b11b197308560b439026c5ce3e4ce1fc (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-01-03T17:04:10Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lilian_almeida_brito.pdf: 1387334 bytes, checksum: b11b197308560b439026c5ce3e4ce1fc (MD5) / Made available in DSpace on 2018-01-03T17:04:10Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) lilian_almeida_brito.pdf: 1387334 bytes, checksum: b11b197308560b439026c5ce3e4ce1fc (MD5) Previous issue date: 2017 / Herbicidas com baixo poder de sor??o podem deixar res?duos no ambiente pass?veis de contamina??o em cursos h?dricos. A passagem dos res?duos para os cursos h?dricos pode ser diminu?da ou mesmo anulada por camadas vegetadas, notadamente, em matas ciliares. Contudo, pouca informa??o existe sob os efeitos de herbicidas em esp?cies florestais, principalmente na fase inicial de desenvolvimento. Com esse prop?sito avaliou-se a sensibilidade das esp?cies Senegalia polyphylla (DC.) Britton & Rose (monjoleiro) e Senna macranthera (DC. Ex collad.) H.S. Irwin & Barnaby (fedegoso) a res?duos dos herbicidas ametryn, atrazine, hexazinone e 2,4-D. Para o primeiro cap?tulo adotaram-se doses correspondentes a 0; 12,5; 25 e 50% daquela comercialmente recomendada de ametryn, atrazine e hexazinone em esquema fatorial 3 x 4 x 2 (herbicidas x doses x esp?cies) com quatro repeti??es, conduzidos em blocos ao acaso em casa de vegeta??o com temperatura controlada. Avaliou-se emerg?ncia, ?ndice de Velocidade de Emerg?ncia (IVE), taxa de mortalidade, massa fresca e seca, altura, di?metro, n?mero de folhas, al?m de vari?veis fisiol?gicas obtidas com aux?lio de um analisador a gases no infravermelho (IRGA). No segundo cap?tulo foram instalados dois experimentos paralelos (um por esp?cie) delineados inteiramente ao acaso em esquema fatorial 2 x 4, correspondentes a duas fontes de 2,4-D (produto comercial DMA? ou auxina Sigma-Aldrich? P.A.) e quatro concentra??es (0; 0,1; 1 e 10 mg.L-1 de 2,4-D), com quatro repeti??es e oito r?plicas cada. As esp?cies foram avaliadas quanto ? germina??o, ?ndice de Velocidade de Germina??o (IVG), contamina??o, di?metro, massa fresca e seca. Como resultado, de maneira geral o monjoleiro se mostrou mais sens?vel aos herbicidas, todavia, demonstrou potencial fitorremediador para atrazine. A compara??o entre os tipos de 2,4-D revela que o herbicida n?o pode ser utilizado como regulador de crescimento em laborat?rio, potencialmente devido aos aditivos que apresenta. Por fim, os resultados apontam que o uso recorrente de herbicidas lixivi?veis pr?ximos a fragmentos florestais podem afetar a perpetua??o de esp?cies nativas por efeito delet?rio silencioso. Novas pesquisas precisam ser realizadas com outras esp?cies nativas a fim de conhecer os efeitos dessas e de outras mol?culas ao ecossistema em geral. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / Herbicides with low sorption capacity can leave residues without an environment liable to contamination in water courses. Passage from the residues to the watercourses can be reduced or even negated by layers vegetated, notably in riparian forests. However, scarce information exists about the effects of herbicides on forest species, especially in the early stages of development. For this purpose the sensitivity of the species Senegalia polyphylla (DC.) Britton & Rose (monjoleiro) and Senna macranthera (DC. Ex collad.) H.S. Irwin & Barnaby (fedegoso) to residues of the herbicides ametryn, atrazine, hexazinone and 2,4-D were evaluated. For the first chapter doses corresponding to 0, 12.5, 25 and 50% of that commercially recommended for ametryn, atrazine and hexazinone were adopted in a 3 x 4 x 2 factorial arrangement (herbicides x doses x species) with four replicates, conducted in randomized blocks under controlled temperature greenhouse. It was evaluated the emergence, Emergency Speed Index (IVE), mortality rate, fresh and dry mass, height, diameter, number of leaves, and physiological variables obtained with the aid of an infrared gas analyzer (IRGA). In the second chapter were installed two parallel experiments (one per species) completely randomly delineated in a 2 x 4 factorial scheme, corresponding to two sources of 2,4-D (commercial product DMA? or auxin Sigma-Aldrich? P.A.) and four concentrations (0; 0,1; 1 e 10 mg.L-1 of 2,4-D), with four repletitons and eight replicates each. The species were evaluated for germination, Germination Speed Index (IVG), contamination, diameter, fresh and dry mass. As a result, in general the monjoleiro showed to be more sensitive to herbicides, however, it demonstrated a phytoremediation potential for atrazine. The comparison between the 2,4-D types reveals that herbicide cannot be used as a growth regulator in the laboratory, potentially due to the additives it presents. Finally, the results indicate that the recurrent use of leachable herbicides close to forest fragments can affect the perpetuation of native species by a silent deleterious effect. New research is done for other native species to know the effects of other molecules on the ecosystem in general.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study aimed to describe the wood anatomy of ten species of the former genus Acacia Mill., as well as to conduct a quantitative agglomerative analysis with 25 species of the same genus, in order to recognize wood anatomical features of diagnostic value to the genera segregated from Acacia Mill. in 2005. The following species were investigated and described, according to IAWA Committee: Acacia acuminata A. Gray, Acacia cambagei R.T. Baker, ex Baker, Acacia harpophylla F. Muell. ex Benth., Acacia koa A. Gray, Acacia rhodoxylon Maiden, Acacia richii A. Gray, Senegalia martiusiana (Steud.) Seigler e Ebinger, Vachellia collinsii Saff., Vachellia nilotica (L.) P. J. H. Hurter e Mabb., e Vachellia planifrons (Wight e Arn.) Ragup., Seigler, Ebinger e Maslin. To the Cluster analysis, anatomical data of another 15 species were collected from the literature. All species share the following features of large occurrence in Fabaceae: diffuse-porous wood; simple perforation plates; vestured intervessel pits; paratracheal parenchyma; libriform fibers; and homogeneous rays. The presence of septate fibers allows to distinguish all the studied species of Senegalia Raf. The occurrence of conspicuous large rays, conjugated with abundant axial parenchyma allows to set apart all Vachellia species from the seven ones, that belongs to the genus Acacia Mill. / Este trabalho teve por objetivo a descrição anatômica de dez espécies de madeira do antigo gênero Acacia Mill., bem como a realização de uma análise quantitativa aglomerativa com dados de 25 espécies do mesmo gênero, com vistas a contribuir para o melhor conhecimento taxonômico, além de reconhecer, na estrutura do lenho, caracteres qualitativos e quantitativos de valor diagnóstico para os táxones segregados em 2005, a partir deste gênero botânico. As descrições basearam-se nas recomendações do IAWA Committee: Acacia acuminata A. Gray, Acacia cambagei R.T. Baker, ex Baker, Acacia harpophylla F. Muell. ex Benth., Acacia koa A. Gray, Acacia rhodoxylon Maiden, Acacia richii A. Gray, Senegalia martiusiana (Steud.) Seigler e Ebinger, Vachellia collinsii Saff., Vachellia nilotica (L.) P. J. H. Hurter e Mabb., e Vachellia planifrons (Wight e Arn.) Ragup., Seigler, Ebinger e Maslin. Na análise de Cluster foram utilizadas as espécies do presente estudo mais outras 15 colhidas na literatura. Todas as espécies apresentam os seguintes caracteres de ampla ocorrência em Fabaceae: porosidade difusa; placas de perfuração simples; elementos vasculares com pontoações ornamentadas; parênquima paratraqueal; fibras libriformes; e raios homogêneos. A presença de fibras septadas permite distinguir as espécies de Senegalia Raf. das demais. Por sua vez, a ocorrência de raios conspícuos, e a abundância de parênquima axial em Vachellia Wight e Arn. permite excluí-la das sete espécies do gênero.

Increasing drought and salinity tolerances in economically important trees adapted to dry land areas is key challenge for maintaining the socioeconomic welfare of dry land areas. Strategies to improve drought and salt tolerance must examine the tree physiological mechanisms that link to the trees survival and growth. This study examined physiological adaptive traits allowing Senegalia senegal to grow better in both saline and dry lands. We conducted two greenhouse experiments and one field study to characterize growth, photosynthetic capacity, water use efficiency (WUE) and gum arabic yield potential among different Senegalia senegal provenances. In the first experiment, we tested early growth and photosynthetic response of seed sources to a cyclic drought treatment. The second greenhouse study examined seed source response to drought, salinity and fertility conditions. Gum yield assessment, growth and WUE of mature trees were determined from a field trial. In general, results showed a high intra genetic variability of Senegalia senegal on gum yield, biomass accumulation and growth. Ngane provenance presented superior growth characteristics as both mature trees and seedlings and exhibited a more conservative water use strategy under drought. Both greenhouse studies revealed similar photosynthetic capacity among Senegalia senegal genotypes when conditions are not limiting. However, when factors such as salinity, fertility and severe drought are involved, different physiological and morphological responses appear and at times this was dependent on seed source. But, at moderate drought stress (chapter 2), no drought by provenance interaction was found. Results of chapter 3 revealed that Ngane has larger stomata with low density in comparison with Diamenar and Kidira provenances. With the exception of Ng21B1, all seed sources displayed similar adaptations to salt stress in term of biomass accumulation. Fertilizer increased total biomass of all seed sources from 63% to 213% for Ng21B1 and K17B19, respectively. However, salinity reduced the fertilizer effect on biomass increment. Leaf gas exchanges were affected by salinity and fertilizer within various responses among seed sources. Results of chapter 4 revealed that gum yield was found to be positively correlated with tree height, crown width, stem volume index and crown area index. Ngane and Diamenar appeared the best provenances in term of annual gum yield per hectare. Diamenar had a higher survival rate than Ngane. This finding reveals the need to consider the tradeoff between tree survival rate and individual tree gum yield in Senegalia senegal stands. In addition to being more sensitive to salinity, Ngane also seems to be more susceptible to low soil pH in terms of survival, but this result needs to be tested further. This study suggests that improvement of gum arabic production can be possible through genetic selection. But, for the best adapted genotypes, research should explore new genetic combination and investigate physiology and genetic diversity. Moreover, the findings on the relationship between soil pH and tree survival rate suggests a need for care in selecting appropriate sites for Senegalia senegal stands. Therefore, silviculture practices as well as genetic selection appear critical in improving gum arabic production. / Ph. D. / <i>Senegalia senegal</i> is a small tree with many uses and the main gum arabic producing species. It is a deciduous tree which grows mainly in arid and semi-arid lands. Since the major drought years of the 1970s and 1980s, a substantial decline of natural stands of the species and the low gum arabic productivity have affected rural incomes in the Sahel where trees such as <i>Senegalia senegal</i> contributes significantly to rural livelihood. Moreover, saline soils are increasing in arid and semi-arid regions where the amount of rainfall is insufficient for substantial evapotranspiration. Therefore, investigating more drought and salt tolerant species will be appropriate in the context of extreme climate events such as drought. However, strategies to improve tolerance need an understanding of physiological mechanisms that link tree growth and adaptation. This study was looking for adaptive characteristics allowing <i>Senegalia senegal</i> to grow better in saline and dry lands while producing more gum arabic. We conducted two greenhouse experiments and one field study to characterize growth, photosynthetic capacity, water use efficiency (WUE, the amount of carbon fixed in photosynthesis per unit water transpired) and gum arabic yield potential among different <i>Senegalia senegal</i> provenances. In the first experiment, we tested growth and biomass allocation to root and shoot of seven <i>Senegalia senegal</i> provenances and their photosynthetic responses to moderate drought treatment. The second greenhouse study was to test five seed sources responses to drought, salinity and fertility conditions. Gum yield assessment, growth and WUE of mature trees were determined in the field study. Globally, results obtained showed a high intra genetic variability of <i>Senegalia senegal</i> on gum arabic yield, biomass accumulation and growth. Ngane provenance presented superior growth characteristics as both mature tree and seedling and exhibited a higher WUE under drought in comparison with the other provenances used in this study. Both greenhouse studies revealed similar photosynthetic capacity among provenances when conditions are not limiting. However, when factors such as salinity, fertility and drought are involved, different physiological and morphological responses appear depending on seed source. But, no drought by provenance interaction was found under drought treatment. Results of chapter 3 revealed that Ngane has larger stomata with low density in comparison with Diamenar and Kidira provenances. Except Ng21B1, all seed sources displayed similar adaptations to salt stress in term of biomass accumulation. Fertilizer has increased total biomass of all seed sources from 63% to 213% for Ng21B1 and K17B19, respectively. However, salinity may reduce the fertilizer effect on biomass increment. Results of chapter 4 revealed that gum yield was found to be positively correlated to tree height and crown width. Ngane and Diamenar appeared as the best provenances in term of annual gum yield per hectare. In addition to be more sensitive to salinity, Ngane seems also to be more susceptible to low soil pH in term of survival. Moreover, the finding on the positive relationship between soil pH and tree survival rate concede a great importance of soil conditions in <i>Senegalia senegal</i> viability. So, in this study it appears critical for the improvement of gum arabic sector to consider both biological component and environmental factors. To seek for best adapted genotypes, research should explore new genetic combinations and investigate physiology and genetic diversity.