O processo de beneficiamento do zinco, extraído em Vazante pela Companhia Mineira de Metais - CMM produz um rejeito alcalino e com baixa disponibilidade de nutrientes. Esta dissertação tem como objetivo avaliar o potencial de utilização de espécies leguminosas noduladas e micorrizadas na revegetação de barragem de rejeito da CMM. Neste sentido, foram instalados dois experimentos de campo onde foi realizado o plantio prévio de Brachiaria sp. O primeiro experimento foi composto por 36 tratamentos que foram formados por uma combinação de 17 espécies + 1 testemunha (ausência de plantas) na presença e na ausência de esterco de curral (2,0 L) na cova de plantio. Cada unidade experimental foi formada por 20 exemplares da mesma espécie que foram plantadas em covas abertas manualmente (25 x 25 x 25 cm) num espaçamento de 2 x 2 m. Todas as covas receberam a adubação básica formada por 125 g de superfosfato simples e 60 g de cloreto de potássio. Entre as 17 espécies avaliadas, 3 não pertencem a família Leguminosae e receberam, além da adubação básica, cerca de 25 g de sulfato de amônio por cobertura. O segundo experimento foi montado com o objetivo de avaliar o potencial de espécies leguminosas beneficiarem o estabelecimento e crescimento de espécies não leguminosas na revegetação de barragem de rejeito da CMM. Foram utilizadas três espécies leguminosas (Enterolobium scomburkii, Acacia mangium e Acacia holosericea) e três não leguminosas (Lithraea brasiliensis, Cinnamomum glaziovii e Eugenia jambolana) num esquema fatorial (3 x 3) + 1 testemunha, formando dez tratamentos distribuídos em blocos ao acaso com três repetições. Cada parcela foi formada por 20 plantas (10 leguminosas + 10 não leguminosas) plantadas em espaçamento 2 x 2 m e com a mesma adubação básica utilizada no primeiro experimento. Todas as espécies leguminosas utilizadas foram previamente inoculadas com estirpes selecionadas de bactérias fixadoras de Nitrogênio atmosférico e com uma mistura de fungos micorrízicos provenientes da Embrapa/Agrobiologia. Os experimentos foram avaliados quanto ao estabelecimento e crescimento de plantas (altura e diâmetro do colo) aos 4, 12 e 24 meses após o plantio. Os resultados obtidos permitem concluir que dentre as espécies avaliadas, as mais indicadas para a primeira etapa da revegetação da barragem de rejeito da CMM são: Acacia holosericea, Acacia farnesiana, Acacia auriculiformis, Mimosa caesalpiniifolia, Leucaena leucocephala, Mimosa birmucronata, Enterolobium schomburkii e Prosopis juliflora. O sucesso do consórcio de espécies leguminosas e não leguminosas depende da escolha das espécies a serem combinadas, de maneira que não exista uma efetiva competição por água, nutrientes e luz que possa prejudicar as espécies de menor plasticidade. Das combinações avaliadas, as de maiores potencialidades para o programa de revegetação das barragens de rejeito da CMM são aquelas envolvendo a espécieLithraea brasiliensis. / The ore milling process at Vazante by Companhia Mineira de Metais - CMM produce an alkaline and low nutrients content refuse. This work had the aim to evaluate the potential of nodulated and mycorrhized legumes shrubs and trees specie at the revegetation of the CMM´s tailing dam. Therefore, two field experiments were carried out at the tailing dam where Brachiaria sp. was previously seemed. The first experiment was formed by a combination of 17 specie + 1 blank (without plants) in the presence and absence of cattle manure (2.0 L) at planting pit. Each experimental unit was composed by 20 individuals of same specie which were planted in handle holes (25 x 25 x 25 cm) at 2 x 2 m lines. Each planting pit received 125 g of super phosphate and 60 g of potassium chlorate. Among the 17 species evaluated, three are not Leguminosae and also received more 25 g of ammonium sulfate by surface application. The second experiment was carried out with the aim to evaluate the potential of leguminous specie to benefit the establishment and growth of non-leguminous specie at the revegetation of the refuse dam. At this experiment three leguminous specie (Enterolobium schomburkii, Acacia mangium and Acacia holosericea) and three non-leguminous specie (Lithraea brasiliensis, Cinnamomum glaziovii and Eugenia jambolana) were combined in a factorial design (3 x 3) + 1 blank, forming 10 trataments. Each experimental unit was composed by 20 plants (10 legumes + 10 non-legumes) planted and fertilized at the same way used at the first experiment. The leguminous specie were previously inoculated and mycorrhized with efficient strains of N-fixation and a misture of mycorrhizal fungi obtained at Embrapa/Agrobiologia. The experiments were evaluated about the plants establishment and growth (height and steam diameter) at 4, 12 and 24 months after the planting time. The obtained results allowed concluding that the indicated specie, among all evaluated, to the first step of the refuse dam revegetation are: Acacia holosericea, Acacia farnesiana, Acacia auriculiformis, Mimosa caesalpiniifolia, Leucaena leucocephala, Mimosa birmucronata, Enterolobium schomburkii e Prosopis juliflora. The success of the combination of leguminous and non-leguminous specie depends to the choice of the specie to avoid competition by water, nutrients and light which may damage the specie with less plasticity. Among all evaluated combinations the more potentiality one to the CMM´s tailing dam revegetation are which envolving L. brasiliensis.

Legume-rhizobia symbioses contribute at least 20% of the biosphere's supply of reactive nitrogen. These unique associations rely on the exchange of specific molecular signals between nitrogen-fixing soil bacteria, collectively called rhizobia, and their host plants and, with few exceptions, result in the formation of root nodules, which provide an environment suitable for nitrogen fixation. However, nitrogen fixation is energetically expensive and nodule proliferation, in much the same manner as the proliferation of other meristems in plants, must be controlled in order to attain equilibrium between cell proliferation and differentiation. Nodule proliferation is controlled primarily and systemically by autoregulation of nodulation (AON). A gene central to this process was first isolated by map-based cloning from soybean (Glycine max) and was named G. max Nodule Autoregulation Receptor Kinase (GmNARK) in accordance with its biochemical and physiological functions. Expression patterns of GmNARK have been described by several investigators; however, these reports were based on either non-quantitative methods or a limited number of tissue types. More importantly, the expression domains of GmNARK were completely unknown. The study described in this thesis utilised techniques such as quantitative RT-PCR (QRTPCR), transcription start site mapping, promoter-reporter gene fusion, and promoter deletion, to analyse the expression levels and domains of GmNARK across a variety of tissues as well as identify the promoter elements that are responsible for the basal and tissue-specific expression of GmNARK. In addition, the promoter activity of GmNARK was also compared with that of Lotus japonicus HAR1, the GmNARK orthologue, in both homologous and heterologous transformation systems. Based on QRT-PCR, GmNARK was expressed to varying levels throughout the plant; the transcript was detected at high levels in mature leaves and roots but to a lesser extent in young leaves, shoot tips and nodules. The transcript level was not significantly affected by Bradyrhizobium japonicum during the first week following inoculation. Histochemical analysis of L. japonicus plants carrying either a 1.7 kb GmNARK promoter or 2.0 kb LjHAR1 promoter fused to a beta-glucuronidase reporter gene localised GUS activity to living cells within vascular bundles, especially phloem cells in leaves, stems, roots, and nodules. Phloem-specific expression was also detected in soybean hairy roots carrying these constructs. These results suggested that both cis- and trans-acting elements required for the transcriptional regulation of these orthologous genes are likely to be conserved. In contrast, 1.7 kb of the GmNARK promoter did not drive phloem-specific expression in Arabidopsis thaliana, indicating the absence of the trans-acting elements required for the tissue-specificity of GmNARK in this distantly related species. The comparison of 2.0 kb of promoter sequences of GmNARK, LjHAR1 and Medicago truncatula SUNN, another GmNARK orthologue, using bioinformatics and computational approaches indicated several highly conserved motifs including a putative negative regulatory region (NRR), which was previously reported to repress gene expression in non-phloem cell types. Deletion analysis of the GmNARK promoter, however, ruled out the possibility that this motif, found at -308 bp with respect to the translation start site, was truly functional and located the region controlling phloem-specific expression to DNA sequence between 908 bp and 1.7 kb upstream of the start codon. Two other candidate regions were identified by Multiple EM for Motif Elicitation (MEME). These regions, namely MEME3 and MEME4 showed strong sequence similarity to the corresponding regions of the LjHAR1 promoter. Interestingly, the MEME3 motif was also found in the MtSUNN promoter at a similar location to that of LjHAR1. Potential NRRs in the LjHAR1 and MtSUNN promoters were found in the MEME3 motifs, whereas only a variant form of a NRR in the GmNARK promoter was found in this region. Additionally, an identical semi-palindromic sequence was also observed in the MEME3 motifs of the three orthologous promoters. Based on these findings, the semi-palindromic sequence and the variant form of the NRR are proposed to be positive and negative regulatory elements for the phloem-specific expression of GmNARK, respectively. The computational approaches also identified two potential TATA elements in the GmNARK promoter. Rapid amplification of 5' cDNA ends and promoter deletion analysis have confirmed that they were functional. The two TATA elements in GmNARK promoter appeared to cooperatively direct transcription of GmNARK, but either was adequate for basal transcription. The finding that the expression of AON receptor-like kinase genes is phloem-specific has contributed to a better understanding of AON signalling pathways. The QRT-PCR study and the discovery of cis-acting regulatory regions have also provided crucial information on the transcriptional regulation of GmNARK as well as plant genes in general. Additionally, the promoters of GmNARK and LjHAR1 could potentially be used to drive phloem-specific expression in legume biotechnology research.

Bibliography: leaves 209-254. Experiments detailed in this thesis, evaluate the impact of various herbicides and herbicide mixtures on the growth, nodulation and nitrogen fixation of annual pasture legumes, the efficacy of the herbicides for weed control, and the potential role of mechanical defoliation to replace herbicides, leading to lower cost and more sustainable farming systems.

Thesis (M. Sc.)(Microbiology)--University of Pretoria, 2005. / Includes bibliographical references. Available on the Internet via the World Wide Web.

The objective of this study was to determine effects of supplementing coastal bermudagrass (Cynodon dactylon; CBG) hay with Strophostyles helvula (98 g kg-1 crude protein (CP), 476 g kg-1 neutral detergent fiber (NDF)), S. leiosperma (117 g kg-1 CP, 497 g kg-1 NDF), or cottonseed meal (506 g kg-1 CP, 352 g kg-1 NDF; CSM) upon intake of CBG hay (127 g kg-1 CP, 691 g kg-1 NDF) and apparent digestibility of dietary organic matter (OM), NDF, and true digestibility of CP. Six Boer-Spanish goats (46.22 +- 3.99 Kg) were fed CBG plus S. helvula, S. leiosperma, or CSM at 0.34 and 0.68% of BW in a 6*6 Latin square with 3*2 factorial arrangement of treatments. The CBG was fed ad libitum, and the legumes/CSM were fed in two equal daily feedings during a 7-d adjustment period and 7-d collection period in metabolism crates. Feces were collected every 24-h, and CBG, legumes/CSM, and fecal samples were analyzed for OM, NDF, and CP. There were no supplement type*amount interactions (P > 0.05). Supplement type did not affect OM digestibility (P = 0.21), but OM digestibility increased 6.4% (P = 0.05) at the 0.68% versus 0.34% level of supplementation with the legumes or CSM. Supplementation with CSM and S. leiosperma improved NDF digestibility 7% versus supplementation with S. helvula (P = 0.02); and as supplement amount increased NDF digestibility by 5.5% (P = 0.02). The diet supplemented with CSM had the greatest CP digestibility, and S. helvula CP was 6% less digestible than S. leiosperma (P = 0.02). As supplement amount increased, CP digestibility increased 7% (P = 0.01). Intake of DM, OM, and NDF of CBG was unaffected (P = 0.56) by supplementation with CSM, S. helvula, and S. leiosperma, but total diet NDF intake of diets supplemented with CSM and S. helvula was 10.5% less than diet supplemented with S. leiosperma (P = 0.01). Considering digestibility and intake, CSM and S. leiosperma were the best supplements fed in this experiment. Strophostyles leiosperma is recommended as use for diet supplementation for goats when CBG hay basal diet is fed.

Thesis (MTech. degree in Agriculture.)--Tshwane University of Technology, 2011. / This study evaluated plant growth and symbiotic performance of four promiscuous-nodulating soybean genotypes and three commercial varieties supplied with a peat-based inoculant of Bradyrhizobium japonicum strain WB74 at three field sites in Mozambique and a pot experiment in South Africa. The sole aim was to assess whether these promiscuous-nodulating soybean genotypes can benefit from inoculation.

D. Tech. Biotechnology and Food Technology. / Assesses the symbiotic dependency of grain and shrub / tree legumes as well as shrub/tree legume species adaptation to different rainfall regimes within five agroecological zones in Botswana, leaves of the test species were sampled.

Experimental plots were overlaid on commercial fields of broccoli (Brassica oleraceae L. var. Italica) and cauliflower (Brassica oleraceae L. var. botrytis L.) to evaluate legume species as interseedings in vegetable production. White clover (Trifolium repens L.), red clover (T. pratense L.), yellow sweet clover (Melilotus officinalis L.), hairy vetch (Vicia villosa Roth.) and crimson clover (T. incarnatum L.) were seeded 4-5 weeks after an early planting of broccoli and a late planting of cauliflower. Crop yields, forage biomass, weed biomass and percent fall ground cover were recorded. / A dry year coupled with difficulties in applying the treatments resulted in low forage biomass. Hairy vetch yielded the most within the early broccoli planting system. High rainfall the next year resulted in high biomass yields. Over the two year study, hairy vetch and crimson clover emerged as the two most productive species. Significant effects on fall weed biomass were observed with broccoli in the second year of the study, where interseeded plots reduced weed populations by at least 66%. No evidence was seen of weed suppression by interseedings prior to harvest. Crop yields were not affected by interseedings. All interseeded treatments provided the minimum of 30% ground cover required to help reduce erosion.

N-transfer from legume to grass when the two were intercropped in the field and the mechanisms of this transfer were studied. Studies involving either alfalfa-grasses or soybean-corn intercrops, were undertaken. Mycorrhizal and P-supplemented (to compensate for the lack of mycorrhizae) intercrops were compared. In these studies, the legume component of intercrops was labelled with $ sp{15}$N and any excess of the label was looked for in the associated grass plants. / There was no reversal of N transport at the legume-fungus interface. N-transfer from legume to grass must therefore, proceed via excretion of N by legume roots and subsequent uptake by grass roots. Soil microorganisms and proximity of plant root systems are important factors affecting N-transfer. Mycorrhizae enhance the transfer by increasing the absorptive efficiency of the receiver plants. / Mycorrhizal fungi enhance the competitiveness of the most mycotrophic component of the mixtures by either improving P uptake or the general nutrient balance of the plant. Mycorrhizal inoculation can decrease the level of P competition between corn and soybean by increasing the availability of P. / The observation that mycorrhizal plants differ in many regards from P-supplemented plants, emphasize the generally poor comprehension of the mycorrhizal symbiosis.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1978. / Bibliography: leaves 198-212. / Microfiche. / xviii, 212 leaves ill. (some col.)