The study examined interactions between morogo plants, arbuscular mycorrhizal fungi (AMF) and Fusarium species. Morogo refers to traditional leafy vegetables that, together with maize porridge, are dominant staple foods in rural areas of the Limpopo Province such as the Dikgale Demographic Surveillance Site (DDSS). Morogo plants grow either as weeds (often among maize), occur naturally in the field or are cultivated as subsistence crops by rural communities. Botanical species of morogo plants consumed in the DDSS were determined. Colonisation of morogo plant roots by AMF and Fusarium species composition in the immediate soil environment were investigated in four of eight DDSS subsistence communities, Isolated AMF were shown to belong to the genera Acaulospora and Glomus. Twelve Fusarium species were isolated from soil among which Fusariurn verticilliodes and Fusarium proliferaturn occurred predominantly. Greenhouse pot trials were conducted to examine the effect of AMF on morogo plant growth (cowpea; Mgna unguiculata) and Fusarium proliferatum levels in soil, Interaction between plants and AMF, as well as tripartite interactions of cowpea plants, AMF and Fusarium proliferatum were investigated. Non-inoculated cowpea plants served as controls for the following inoculations of cowpea in pots: (i) Fusarium proliferatum; (ii) commercial AMF from Mycoroot (PTY) Ltd. (a mixture of selected indigenous Glomus spp referred to commercial AMF for the purpose of this study); (iii) indigenous AMF obtained from DDSS soil (referred to iocal AMF for the purpose of this study); (iv) commercial AMF plus Fusarium proliferatum; (v) local AMF plus Fusariurn proliferatum. Results showed reduced root colonization by local as well as commercial AMF when Fusarium proliferatum were present. Local AMF significantly enhanced cowpea growth while commercial AMF apparently reduced the level of Fusarium proliferatum in the rhizosphere and surrounding soil. Results suggest that AMF may have potential as biological growth enhancers and bioprotective agents against Fusarium proliferatum. / Thesis (M. Environmental Science (Water Science))--North-West University, Potchefstroom Campus, 2007.

The study examined interactions between morogo plants, arbuscular mycorrhizal fungi (AMF) and Fusarium species. Morogo refers to traditional leafy vegetables that, together with maize porridge, are dominant staple foods in rural areas of the Limpopo Province such as the Dikgale Demographic Surveillance Site (DDSS). Morogo plants grow either as weeds (often among maize), occur naturally in the field or are cultivated as subsistence crops by rural communities. Botanical species of morogo plants consumed in the DDSS were determined. Colonisation of morogo plant roots by AMF and Fusarium species composition in the immediate soil environment were investigated in four of eight DDSS subsistence communities, Isolated AMF were shown to belong to the genera Acaulospora and Glomus. Twelve Fusarium species were isolated from soil among which Fusariurn verticilliodes and Fusarium proliferaturn occurred predominantly. Greenhouse pot trials were conducted to examine the effect of AMF on morogo plant growth (cowpea; Mgna unguiculata) and Fusarium proliferatum levels in soil, Interaction between plants and AMF, as well as tripartite interactions of cowpea plants, AMF and Fusarium proliferatum were investigated. Non-inoculated cowpea plants served as controls for the following inoculations of cowpea in pots: (i) Fusarium proliferatum; (ii) commercial AMF from Mycoroot (PTY) Ltd. (a mixture of selected indigenous Glomus spp referred to commercial AMF for the purpose of this study); (iii) indigenous AMF obtained from DDSS soil (referred to iocal AMF for the purpose of this study); (iv) commercial AMF plus Fusarium proliferatum; (v) local AMF plus Fusariurn proliferatum. Results showed reduced root colonization by local as well as commercial AMF when Fusarium proliferatum were present. Local AMF significantly enhanced cowpea growth while commercial AMF apparently reduced the level of Fusarium proliferatum in the rhizosphere and surrounding soil. Results suggest that AMF may have potential as biological growth enhancers and bioprotective agents against Fusarium proliferatum. / Thesis (M. Environmental Science (Water Science))--North-West University, Potchefstroom Campus, 2007.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2018-08-14T17:26:05Z No. of bitstreams: 1 Dissertação - Catalogada Igor.pdf: 1880759 bytes, checksum: 622a5c7c24e54df511092cf0eed620d5 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2018-08-17T12:20:33Z (GMT) No. of bitstreams: 1 Dissertação - Catalogada Igor.pdf: 1880759 bytes, checksum: 622a5c7c24e54df511092cf0eed620d5 (MD5) / Made available in DSpace on 2018-08-17T12:20:33Z (GMT). No. of bitstreams: 1 Dissertação - Catalogada Igor.pdf: 1880759 bytes, checksum: 622a5c7c24e54df511092cf0eed620d5 (MD5) Previous issue date: 2017-12-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O feijão caupi (Vigna unguiculata) é produzido principalmente em pequenas propriedades da região nordeste do país. Com o déficit na oferta de feijão e os preços atrativos observados na entressafra, grandes produtores da região Centro-Oeste passaram a cultivar feijão caupi, especialmente da variedade Bico de Ouro. Por se tratar de uma dicotiledônea com hábito de crescimento indeterminado, as plantas apresentam vagens secas, vagens no ponto ideal e vagens verdes no momento da colheita. A colheita manual em grandes propriedades é inviável, sendo necessária a aplicação de herbicidas para uniformizar a senescência das plantas e o grau de maturação dos grãos para, então, viabilizar a colheita mecanizada. Desta forma objetivou-se com o presente estudo: (1) Avaliar as consequências da utilização de herbicidas dessecantes em pré-colheita sobre propriedades químicas e tecnológicas do feijão caupi da variedade Bico de Ouro, e (2) Avaliar efeitos da temperatura e da atmosfera de armazenamento sobre propriedades tecnológicas do feijão caupi da variedade Bico de Ouro. Os herbicidas glifosato (GLI), glifosato mais carfentrazona (GLI/CAR) e paraquate (PAR) foram testados em pré-colheita, no primeiro estudo. Grãos colhidos manualmente foram utilizados como controle (SEM). Os grãos foram, também, armazenados a 25ºC, por 8 meses, para avaliar a suscetibilidade ao envelhecimento. Para o segundo estudo, grãos de feijão caupi da variedade Bico de Ouro foram armazenados por 8 meses com nitrogênio ou em atmosfera hermética, a 15, 20 ou 25°C. A aplicação de herbicidas dessecantes na pré-colheita proporcionou alterações nos parâmetros de qualidade. Grãos obtidos de plantas tratadas com PAR e GLI apresentaram coloração mais escura logo após a colheita. No entanto, no armazenamento, a cor do tegumento dos grãos obtidos de plantas tratadas com PAR se manteve mais estável. A aplicação de GLI proporcionou acúmulo em níveis mais elevados de compostos fenólicos, principalmente compostos complexos como as proantocianidinas. Foi possível identificar moléculas de discriminação do feijão caupi em função do herbicida utilizado, sendo elas: catequina-3-glicosídeo e epicatequina (para grãos obtidos de plantas tratadas com GLI), ácido cítrico (para grãos de plantas tratadas com GLI/CAR), e quercetina e ácido glucônico (para grãos obtidos de plantas não submetidas ao tratamento com herbicidas). Os teores residuais de glifosato e paraquate foram superiores aos limites máximos tolerados pelo Codex Alimentarius e pela União Européia. Em relação ao segundo objetivo apresentado, o feijão caupi armazenado em atmosfera com nitrogênio a 20°C manteve atributos de cor, cocção e dureza muito próximos aos grãos armazenados pelo mesmo período a 15°C. / Cowpea (Vigna unguiculata) is produced mainly in small properties in the northeastern region of the country. With the deficit in the supply of beans and the attractive prices observed in the off season, large producers of the central-west region began to grow cowpea beans, especially the Bico de Ouro variety. Because it is a dicotyledon with an indeterminate growth habit, the plants present dry pods, pods at the ideal point and green pods at the time of harvest. The manual harvesting on large properties is impracticable, being necessary the application of desiccants to standardize the senescence of the plants and the degree of maturation of the grains in order to allow the mechanized harvesting. Thus, this study aimed to: 1) To evaluate the consequences of using pre-harvest desiccants, end 2) Evaluate effects of storage temperature and atmosphere on the technological properties of cowpea, variety Bico de ouro. The herbicides glyphosate (GLI), glyphosate with carfentrazone (GLI/CAR), end paraquat (PAR) were tested in pre-harvest, in the first study. Cowpeas collected manually were used as control (SEM). The grains were also stored at 25°C for 8 months to evaluate the susceptibility to aging. In the second study, cowpea of the Bico de ouro variety were stored for 8 months under nitrogen or in a hermetic atmosphere at 15, 20 or 25°C. The application of herbicides in the pre-harvest changed the quality parameters of the cowpea. Cowpeas obtained from PAR and GLI treated plants showed darker coloration soon after harvest. However, in storage, the color of the cowpea coat treated with PAR remained more stable. The application of GLI provided accumulation at higher levels of phenolic compounds, especially complex compounds such as proanthocyanidins. It was possible to identify molecules of cowpea discrimination as a function of the herbicide used, being them: catechin-3- glycoside and epicatechin (for grains obtained from plants treated with GLI), Citric acid (for grains obtained from plants treated with GLI/CAR), end quercetin end gluconic acid (for grains obtained from plants not submitted to treatment with herbicides). Residual levels of glyphosate and paraquat were higher than the maximum levels tolerated by the Codex Alimentarius and the European Union. With regard to the second objective, the cowpea stored in nitrogen atmosphere at 20°C maintained color, firing and hardness attributes very close to the grains stored for the same period at 15°C.

The reported requirement for a higher weeding effort due to increased weed infestations under conservation agriculture (CA) relative to conventional mouldboard plough tillage is perceived by both smallholder farmers and extension workers as the main limiting factor to the widespread adoption of CA by smallholder farmers in southern Africa. However, proponents of CA argue that weeds are only a problem under CA in the initial two years and decline afterwards resulting in reduced labour requirements for weeding under CA. They further posit that weeds are only major problem where minimum tillage (MT) is adopted without crop residue mulching and diverse crop rotations. This thesis explores the effect of time under CA on weed population dynamics and crop growth under the recommended CA practices and actual smallholder farmer practice in semi-arid Zimbabwe. Assessment of weed and crop growth on a long-term CA experiment at Matopos Research Station revealed that the MT systems of planting basins and ripper tine were associated with higher early season weed density and biomass than conventional early summer mouldboard tillage (CONV) in both the fifth (cowpea phase) and sixth (sorghum phase) years of CA. This increased weed infestation within the first four weeks after planting in CA necessitated early weeding to provide a clean seedbed and avert significant crop yield loss. Maize mulching only suppressed early season weed growth in sorghum mostly at a mulch rate of 8 t ha-1 which is not a mulching rate that is attainable on most smallholder farms. However, the lower maize residue mulch rate of 4 t ha-1 was consistently associated with increased weed emergence and growth as from the middle of the cropping season in both crop species. The increased weed infestations under the mulch were probably due to the creation of ‘safe sites’ with moist conditions and moderate temperatures. The high weed growth under the mulch contributed to the low sorghum grain yield obtained under mulched plots. In addition, maize mulching was also associated with a less diverse weed community that was dominated by the competitive Setaria spp. and difficult to hoe weed Eleusine indica (L.) Gaertn. However, the weed community under CA was similar to that under CONV tillage with no evidence of a shift to the more difficult to control weed species. The increased early season weed growth and high weed pressure under CA meant that it was still necessary to hoe weed four times within the cropping season to reduce weed infestations and improve crop growth even after four years of recommended CA practices. Early and frequent weeding was effective in reducing weed growth of most species including Setaria spp. and E. indica demonstrating that on smallholder farms where labour is available hoe weeding can provide adequate weed control. The wider spacing recommended for use in CA contributed to the low cowpea and sorghum grain yields obtained under CA compared to CONV tillage. On smallholder farms in Masvingo District, the MT system of planting basin (PB) was the only conservation farming (CF) component adopted by farmers. There was no difference in the total seedling density of the soil weed seed bank and density of emerged weeds in the field in PB and conventional mouldboard ploughing done at first effective rains (CONV tillage). However, the first weeding in PB was done at least 15 days earlier (P < 0.05) than in CONV tillage suggesting high early season weed growth in PB relative to CONV tillage. As weed density did not decline with time in PB, weed management did not differ with increase in years under PB. Shortage of inputs such as seed and fertiliser was identified by smallholder farmers as the most limiting factor in PB crop production with the area under PB was equivalent to the seed and fertiliser provided by CARE International for most farmers. On this small area, weeds could be managed by available family labour. Double the maize grain yield was obtained in PB (mean: 2856 kg ha-1) due to improved weed management and soil fertility. However, the use of poorly stored composts was found to introduce weeds into some PB fields. The findings of this study demonstrated that weed pressure was still high and weed management were still a challenge under the practice recommended to smallholder farmers in Zimbabwe even in the sixth year of practice. There is, therefore, a need for research on the economic feasibility of using herbicides, intercropping and optimal crop density to ameliorate the high weed pressure under CA. / Thesis (PhD)--University of Pretoria, 2013. / Plant Production and Soil Science / unrestricted