Orientador: Lin Chau Ming / Banca: Maria Christina de Mello Amorozo / Banca: Moacir Haverroth / Resumo: As dioscoreáceas constituem uma importante fonte alimentar e estão distribuídas nas regiões tropicais, subtropicais e temperadas de todo mundo. O gênero Dioscorea, ao qual pertence a maioria das espécies cultivadas e silvestres da família, engloba espécies tropicais originárias da África, Ásia e América. O objetivo do trabalho foi realizar um levantamento das variedades de cará (Dioscorea spp.) cultivadas pelos agricultores com o intuito de verificar as espécies mantidas por eles e suas diversidades, nomes populares das variedades e sobre o sistema produtivo da cultura como: preparo das túberas sementes, manejo da cultura, preparo do solo, plantio, tratos culturais e comercialização. Para o início da pesquisa de campo, foi usada a técnica de amostragem do tipo "bola de neve", que consistiu em conversar com alguns agricultores e vendedores dos mercados de hortaliças da região para a localização dos principais agricultores que cultivam o cará e suas indicações subsequentes. Durante a pesquisa de campo, foram encontrados 48 agricultores que cultivam diversas culturas e também plantam o cará, com seu respectivos nomes populares para o gênero. Foram encontradas três espécies: Dioscorea alata, D. trifida e D. bulbifera. O preparo do solo é feito de forma rudimentar e o cultivo do cará é feito no sistema de "roça de toco". 14% dos agricultores utilizaram algum tipo de implemento agrícola para o preparo do solo. O preparo das "sementes" varia de acordo com cada espécie, sendo que 55% são plantadas partidas e 45% inteiras. A organização e destino da produção acontecem nas comunidades, onde grande parte é destinada à alimentação familiar, e o excedente é para a venda direta para consumidores ou via intermediários / Abstract: The dioscoreaceas constitute an important source of food and are distributed in tropical, subtropical and temperate all over the world. The genus Dioscorea, whose the most cultivated and wild species of the family belong to, encompassing tropical species originally from Africa, Asia and America. The objective was to survey the varieties of yams grown by farmers in order to verify the species kept by them and their diversity, popular names of the varieties and the crop production system as: preparation of tubers-seeds, crop management, soil preparation, planting, cultivation and marketing. In the field research the sampling "snowball", was used, which consisted of talking to some farmers and vegetable sellers in the region for the location of the main farmers who grow yams. During the fieldwork, there were 48 farmers growing different crops and also plant the yams, their respective common names for the genus. Three species were found: Dioscorea alata, D. trifida and D. bulbifera. Soil preparation is done rudimentary and the cultivation of yams is done on a "slash and burn" system. 14% of farmers used some type of agricultural implement for soil tillage. The "seed" preparation varies with each species, 55% are planted using divided portions of the tubers and 45% using entire tubers. The organization of production and destination are done in communities where a large part is devoted to the family diet, and the surplus is for sale delivered directly to consumers or by middle-men / Mestre

Made available in DSpace on 2014-06-11T19:26:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-18Bitstream added on 2014-06-13T20:55:01Z : No. of bitstreams: 1 ferreira_ab_me_botfca.pdf: 1827601 bytes, checksum: b017d5489f44eb1c042dcabf9e93e729 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As dioscoreáceas constituem uma importante fonte alimentar e estão distribuídas nas regiões tropicais, subtropicais e temperadas de todo mundo. O gênero Dioscorea, ao qual pertence a maioria das espécies cultivadas e silvestres da família, engloba espécies tropicais originárias da África, Ásia e América. O objetivo do trabalho foi realizar um levantamento das variedades de cará (Dioscorea spp.) cultivadas pelos agricultores com o intuito de verificar as espécies mantidas por eles e suas diversidades, nomes populares das variedades e sobre o sistema produtivo da cultura como: preparo das túberas sementes, manejo da cultura, preparo do solo, plantio, tratos culturais e comercialização. Para o início da pesquisa de campo, foi usada a técnica de amostragem do tipo “bola de neve”, que consistiu em conversar com alguns agricultores e vendedores dos mercados de hortaliças da região para a localização dos principais agricultores que cultivam o cará e suas indicações subsequentes. Durante a pesquisa de campo, foram encontrados 48 agricultores que cultivam diversas culturas e também plantam o cará, com seu respectivos nomes populares para o gênero. Foram encontradas três espécies: Dioscorea alata, D. trifida e D. bulbifera. O preparo do solo é feito de forma rudimentar e o cultivo do cará é feito no sistema de “roça de toco”. 14% dos agricultores utilizaram algum tipo de implemento agrícola para o preparo do solo. O preparo das “sementes” varia de acordo com cada espécie, sendo que 55% são plantadas partidas e 45% inteiras. A organização e destino da produção acontecem nas comunidades, onde grande parte é destinada à alimentação familiar, e o excedente é para a venda direta para consumidores ou via intermediários / The dioscoreaceas constitute an important source of food and are distributed in tropical, subtropical and temperate all over the world. The genus Dioscorea, whose the most cultivated and wild species of the family belong to, encompassing tropical species originally from Africa, Asia and America. The objective was to survey the varieties of yams grown by farmers in order to verify the species kept by them and their diversity, popular names of the varieties and the crop production system as: preparation of tubers-seeds, crop management, soil preparation, planting, cultivation and marketing. In the field research the sampling snowball, was used, which consisted of talking to some farmers and vegetable sellers in the region for the location of the main farmers who grow yams. During the fieldwork, there were 48 farmers growing different crops and also plant the yams, their respective common names for the genus. Three species were found: Dioscorea alata, D. trifida and D. bulbifera. Soil preparation is done rudimentary and the cultivation of yams is done on a “slash and burn” system. 14% of farmers used some type of agricultural implement for soil tillage. The “seed” preparation varies with each species, 55% are planted using divided portions of the tubers and 45% using entire tubers. The organization of production and destination are done in communities where a large part is devoted to the family diet, and the surplus is for sale delivered directly to consumers or by middle-men

Master of Science / Department of Agronomy / Charles W. Rice / Declining soil health is the underlying cause of decreasing agricultural productivity and environmental degradation. To address this challenge, research was conducted to determine how: (1) cover crops affect soil health in Kansas, USA and (2) direct seeding mulch–based cropping (DMC) systems affect soil health in Nyankpala, Ghana. Soil health indicators assessed include: biomass yield (kg ha[superscript]-1), soil microbial respiration (SMR), soil microbial C and N (MBC & MBN), potentially mineralizable N (PMN), dissolved organic carbon (DOC), soil organic C (SOC), soil total nitrogen (TN), phospholipid fatty acid analysis (PLFA), water stable aggregate (WSA), bulk density, pH, N, P, K, Ca and Mg. DMC systems from Ghana yielded significantly greater biomass compared to the control. High biomass produced by DMC systems did not increase SOC and PMN relative to the control. Fertilizer application had a significant impact on biomass production, which resulted in a significant increase in SOC and PMN in the 0-5 cm soil layer. Soil pH was significantly reduced by cropping systems and fertilizer in the 0-5 cm soil layer. Microbial biomass N, TN, SMR, N, P, Ca and Mg were not affected by the DMC cropping systems. Application of mineral fertilizer increased SMR, MBN, TN, N, and P. Soil K was also significantly affected by cropping systems and mineral fertilizer. The combination of mineral fertilizer and plant residues would be needed to improve soil health and increase crop productivity in the Guinea Savanna Zone of Ghana. Liming would be required to address low soil pH. In the USA, of all the soil health indicators examined, actinomycetes, gram-positive bacteria, fungi-bacteria ratio (F:B), SMR, MBN and WSA, were those significantly influenced by cover crops. The interactive effect of cover cops and N fertilizer also affected gram-positive bacteria, total PLFA, MBN, F:B ratio and WSA. Cover crop residues contributed to the observed differences in these indicators. The low response of soil health indicators suggest further evaluations are needed to determine the effectiveness of the indicators.

Master of Science / Agronomy / Robert Aiken / Xiaomao Lin / Productivity of water-limited cropping systems can be reduced by untimely distribution of water as well as cold and heat stress. The research objective was to develop relationships among weather parameters, water use, and grain productivity to produce production functions to forecast grain yields of grain sorghum and winter wheat in water-limited cropping systems. Algorithms, defined by the Kansas Water Budget (KSWB) model, solve the soil water budget with a daily time step and were implemented using the Matlab computer language. The relationship of grain yield to crop water use, reported in several crop sequence studies conducted in Bushland, TX; Colby, KS and Tribune, KS were compared against KSWB model results using contemporary weather data. The predictive accuracy of the KSWB model was also evaluated in relation to experimental results. Field studies showed that winter wheat had stable grain yields over a wide range of crop water use, while sorghum had a wider range of yields over a smaller distribution of crop water use. The relationship of winter wheat yield to crop water use, simulated by KSWB, was comparable to relationships developed for four of five experimental results, except for one study conducted in Bushland that indicated less crop water productivity. In contrast, for grain sorghum, experimental yield response to an increment of water use was less than that calculated by KSWB for three of five cases; for one study at Colby and Tribune, simulated and experimental yield response to water use were similar. Simulated yield thresholds were consistent with observed yield thresholds for both wheat and sorghum in all but one case, that of wheat in the Bushland study previously mentioned. Factors in addition to crop water use, such as weeds, pests, or disease, may have contributed to these differences. The KSWB model provides a useful analytic framework for distinguishing water supply constraints to grain productivity.

Made available in DSpace on 2016-06-02T18:57:49Z (GMT). No. of bitstreams: 1 5731.pdf: 10443315 bytes, checksum: 6ee3add6c6df69821536597088d1b32d (MD5) Previous issue date: 2013-12-04 / Universidade Federal de Sao Carlos / Sugarcane plantations are increasing in Brazil motivated by the demand of the sugar industry and the energetic sector. Sugarcane monocultures simplify the landscape and disconnect natural ecosystems. The inclusion of native trees in the canebrake, changing the matrices into an alley cropping system, is a new proposal that consider the environment beyond production. In order to assess the environmental effects in agroforestry was raised sugarcane productivity and development of trees in three crops (2009/10, 2010/11 and 2011/12), as well as the timber volume and carbon sequestration produced by the system at the end of the year 2012 and a bird survey during 2011 and 2012 in an experimental area of 1,957 hectares. Was found orderly development of tree species. Schizolobium parahyba present a significant mortality, but had the largest wood production thus coming to the same conclusion in relation to carbon sequestration, which are 3 times those of the Handroanthus spp. and 2 times the Cedrela fissilis. There was no change in the sugarcane productivity related to the distance line planting was the alley, with only a drop productivity in the range of 58 m cultivation. Birds are important bioindicators; trees contributed to the increased diversity of birds, being Schizolobium parahyba the arboreal species of most relevant importance. The spacing between alleys with the greatest diversity of birds was to 29 m. It is concluded that it is technically possible deployment agroecosystem proposed, without agronomic production damage of cane sugar; the 2 smaller bands cultivation (29 m and 43.5 m) are the most suitable; among tree species Schizolobium parahyba was the one with the best results in the short term, since the issue of mortality could be remedied with proper management or replanting. / O plantio de cana-de-açúcar está em franca expansão no Brasil motivado pela demanda do setor sucroenergético. Os canaviais em matrizes monoculturais simplificam a paisagem e desconectam ecossistemas naturais. A inserção de aleias com árvores nativas em canavial é uma nova proposta que contempla o ambiente além da produção. Com o objetivo de avaliar os efeitos ambientais e a produtividade agrossilvicultural nesse sistema agroflorestal, foram levantados em uma área experimental de 1,957 hectares, o rendimento da cana-de-açúcar e o desenvolvimento das árvores constituintes das aleias em 3 safras (2009/10, 2010/11 e 2011/12); bem como o volume de madeira produzido e a fixação de carbono pelo sistema ao final do ano de 2012; e a dinâmica da avifauna durante os anos de 2011 e 2012. Constatou-se um desenvolvimento regular das espécies arbóreas, observando grande taxa de mortalidade do guapuruvu (60%). Foi possível constatar a maior produção de madeira pelo guapuruvu, consequentemente chegando aos mesmos resultados em relação à fixação de carbono, sendo estes 3 vezes superiores aos do ipê e 2 vezes ao cedro. A produtividade da cana não esteve relacionada com a distância entre a linha de plantio e a aleia, apresentando queda apenas na faixa de cultivo de 58 m. A avifauna foi considerada um bioindicador consistente; o guapuruvu foi a espécie florestal com maior importância para o aumento da diversidade de aves e o espaçamento entre aleias com a maior riqueza foi o de 29 m. Conclui-se que é tecnicamente possível a implantação do agrossistema proposto, sem prejuízo agronômico da produção da cana-de-açúcar, sendo as 2 menores faixas de cultivo (29 e 43,5 m) as mais propícias e o guapuruvu a espécie arbórea com melhores resultados em curto prazo, desde que a questão da mortalidade seja sanada com replantio ou manejo adequado.

Resumo: - Com o objetivo de avaliar a produtividade e rentabilidade dos consórcios de pepino, em duas densidades populacionais, com dois grupos de alface (crespa e americana), em ambiente protegido, realizados em duas épocas de cultivo, agosto a novembro de 2005 e fevereiro a maio de 2006, foram realizados oito experimentos na Unesp, Campus de Jaboticabal-SP. Cada experimento constou de nove tratamentos, resultante de quatro cultivos consorciados (estabelecidos em quatro épocas de transplante da alface em relação ao pepino: O, 10, 20 e 30 dias) e cinco monoculturas, sendo quatro com alface estabelecida nestas mesmas épocas de transplante e um com o pepino, instalado sob delineamento experimental de blocos casualizados, com quatro repetições. As cultivares utilizadas nos experimentos foram o híbrido de pepino japonês 'Hokushin', e 'Lucy Brown' e 'Verônica', respectivamente, para alface americana e crespa. A determinação do custo de produção do cultivo consorciado foi realizada com base na metodologia do custo operacional de produção, no mês de agosto de 2006. A produtividade e a classificação dos frutos de pepino em cultivo consorciado, independente da cultivar de alface, não diferem das obtidas em monocultura. As maiores produtividades comerciais e totais de pepino são obtidas nos cultivos consorciados de alface crespa, sendo indiferente a densidade populacional, e de americana com 1,11 planta m-2 de pepino, todos em cultivos na segunda época. A produtividade das plantas de alface é afetada pela época de estabelecimento do consórcio, definido pelo transplante da alface em relação ao transplante do pepino. As plantas de alface crespa e americana cultivadas em consórcio, na segunda época de cultivo, não apresentam qualidade comercial. O índice de eficiência... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In order to analyze the yield and profitability of cucumber intercropping, in two plant population densities, with two groups of lettuce (crisp and crisphead), in a protected environment, for two cultivation periods, from August to November 2005, and from February to May 2006, eight experiments were conducted at the Unesp Campus in Jaboticabal, SP. Each experiment consisted of nine treatments, resultant of four intercropping cropping (established in four times of transplant of lettuce in relation to the cucumber: O, 10, 20 and 30 days) and five monocultures, being four with established lettuce in these same transplant times and one with the cucumber, and was arranged in a randomized block design, with four replications. 'Hokushin', a hybrid of Japanese cucumber, 'Lucy Brown' and 'Veronica', for crisphead and crisp lettuce, respectively, were the cultivars used in the experiments. The operating cost of production method was used for calculating the production cost of the intercropping cultivation in August 2006. The yield and grade of cucumber fruits under intercropping cultivation, regardless of the lettuce cultivar, do not differ from those obtained through single cropping cultivation. The highest total market yields of cucumber are obtained through the intercropping cultivation with crisphead lettuce, regardless of the population density, and with crisphead lettuCe at 1.11 plant m-2 of cucumber, ali in the second cultivation period. The yield of lettuce plants is affected by the date the intercropping is established, establishment which is determined by the transplanting of lettuce in relation to the transplanting of cucumber. Crisp and crisphead lettuce plants, under intercropping and grown in the second cultivation period, do not have any market quality. The land equivalent ratio is... (Complete abstract click electronic access below) / Orientador: Arthur Bernardes Cecílio Filho / Coorientador: Maria Inez Espagnoli Geraldo Martins / Coorientador: José Carlos Barbosa / Banca: Francisco Bezerra Neto / Banca: Leilson Costa Grangeiro / Banca: Maria Madalena Zocoller Borba / Banca: Izabel Cristina Leite / Doutor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The region of the Table Lands Sergipano is characterized by intense intemperization, because the influence of the high regime of rainfall and conditions of high temperature, so that there are mainly changes in physical and chemical properties of soil. The search for productive and environmental sustainability in agroecosystems is necessary to measure indicators of soil quality, to determine the behavior of physical attributes, chemical and microbiological for them to develop a management systems that degrade less the environment without compromising the productivity. This work have for aim evaluate the quality soil, through indicators of quality in different management systems (no-tillage, minimum tillage and conventional tillage), using leguminous plants (plants coverage: Pea (Cajanus cajan) and Sunn hemp (Crotalaria juncea); plants commercial: Bean (Phaseolus vulgares) and Peanut (Arachis hypogea)) in succession to the cultivation of sweet corn in agroecosystem of a soil classified as Ultissol Red Yellow located on the Campus Rural of the University Federal of Sergipe. The agronomics parameters were assessed: physical (mechanical resistance to penetration, density, diameter average weighted and percentage of aggregates stable in water), chemical (cation exchange capacity, base saturation and content of phosphorus) and microbiological (microbial biomass, breath basal and ratio of breath). The system notillage went who more contributed for improve the quality of soil proportianing better conditions physical, chemical and microbiological to the soil as: lower value of resistance to penetration from the depth of 20 cm, higher value of diameter average weighted, higher percentage of aggregates stable in water, higher value of CTC (cation exchange capacity), higher value of V (base saturation), higher value on the content of phosphorus, higher microbial biomass, lower value of breath basal, lower value of ratio of breath, higher value of total organic carbon. On the cultures tested in succession there was a large variation in results, with the plots where the sun hemp (Crotalaria juncea) was grown, it was obtained lower mechanical resistance to penetration at all depths no system no-tillage. In plots where it was grown pea (Cajanus cajan) were obtained highest values of phosphorus in the system no-tillage. The highest yield of sweet corn (Zea mays L.) was obtained in the system of cultivation no-tillage in respect minimum tillage and conventional tillage, and the sunn hemp provided greater productivity of sweet corn (Zea mays L.) in minimum tillage systems and conventional. The bean (Phaseolus vulgares) provided the greatest productivity of sweet corn (Zea mays L.) cultivation system no-tillage. / A região dos Tabuleiros Costeiros Sergipano é caracterizada pela intensa intemperização, devido a influência do regime alto de precipitação e condições de alta temperatura, fazendo com que haja alterações principalmente nas propriedades físicas e químicas do solo. A busca pela sustentabilidade produtiva e ambiental nos agroecossistemas se faz necessária a mensuração de indicadores de qualidade do solo, para determinar o comportamento dos atributos físicos, químicos e microbiológicos para que possa desenvolver um sistemas de manejo que degrade menos o meio ambiente sem comprometer a produtividade. O presente trabalho tem por objetivo avaliar a qualidade do solo, através de indicadores de qualidade em diferentes sistemas de manejo (Plantio Direto, Cultivo Mínimo e Cultivo Convencional), utilizando plantas leguminosas (Plantas de cobertura: Guandu (Cajanus cajan) e Crotalária (Crotalaria juncea); Comerciais: Feijão (Phaseolus vulgares) e Amendoim(Arachis hypogea)) em sucessão ao cultivo do Milho doce em um agroecossistema de solo classificado como ARGISSOLO VERMELHO Amarelo localizado no Campus Rural da Universidade Federal de Sergipe. Os parâmetros agronômicos avaliados foram: físicos (resistência mecânica à penetração, densidade, diâmetro médio ponderado e percentagem de agregados estáveis em água), químicos (capacidade de troca catiônica, saturação por bases e Teor de fósforo) e microbiológicos (biomassa microbiana, respiração basal e quociente de respiração). O sistema de cultivo Plantio Direto foi que mais contribuiu para melhorar a qualidade do solo proporcionando melhores condições físicas, químicas e microbiológicas ao solo como: menor valor de resistência mecânica à penetração a partir da profundidade de 20 cm, maior valor de diâmetro médio ponderado, maior percentual de agregados estáveis em água, maior valor de CTC (capacidade de troca catiônica), maior valor de V (saturação por bases), maior valor quanto ao Teor de fósforo, maior valor de biomassa microbiana, menor valor de respiração basal, menor valor de quociente de respiração, maior valor de carbono orgânico total. Quanto às culturas em sucessão testadas houve uma grande variação nos resultados, sendo que nas parcelas onde foi cultivada a Crotalária (Crotalaria juncea), obteve-se menores valores de resistência mecânica à penetração em todas as profundidades no sistema de cultivo Plantio Direto. Nas parcelas onde foi cultivado o Guandu (Cajanus cajan) foram obtidos maiores valores de fósforo no sistema de cultivo Plantio direto. A maior produtividade de milho doce foi obtida no sistema de cultivo Plantio Direto em relação aos Cultivo Mínimo e Convencional, sendo que a crotalária (Crotalaria juncea) proporcionou maior produtividade de milho doce (Zea mays L.) nos sistemas de Cultivo Mínimo e Convencional. O feijão proporcionou maior produtividade de milho doce (Zea mays L.) no sistema de cultivo Plantio Direto.

Made available in DSpace on 2016-07-18T17:53:17Z (GMT). No. of bitstreams: 1 Juliana Santiago Santos.pdf: 239926 bytes, checksum: 84b7e3da790d27b6da94f61e5c44260e (MD5) Previous issue date: 2016-05-19 / The consumption of green-leafy vegetables has been incentivized given the scientific data showing the presence of nutritional characteristics associated with human health benefits. Notwithstanding the microbiological quality in green leafy vegetables has generated interest in preoccupation in researchers seeing that they transmit pathogens to humans, especially parasitical agents of zoonotic importance. The present study analyses the parasitological contamination in curly lettuce (Lactuca sativa) cultivated in different production systems (conventional, organic and hydroponic) supplied for a family garden co-operative, in Presidente Prudente, São Paulo. The harvests of collection were repeated at weekly intervals, during a period of five months, yielding 180 samples. The lettuce were washed with Extran MA 02 a 0.5% and the resulting fluid submitted to centrifuge-sedimentation and flotation techniques, in order to recover the parasites structures. Contamination enteroparasites was observed in all production systems, although more frequently in vegetables grown in hydroponic system. It was observed that 71 (39.4%) samples were contaminated with at least one parasitic structure: 34 (18.9%) of lettuce grown in the hydroponic, 20 (11.1%) in the organic and 17 (9.4%) in the conventional system. Cysts of Entamoeba spp. were the most common parasitic structures in vegetables, and the most cysts counted were those produced in the hydroponic system (p = 0.003). Other parasitic structures were observed less frequently. Eggs or Trichostrongyloid larvae were recovered in lettuce cultivated in the three systems. Strongyloides spp. eggs were found in conventional and organic systems, while a larva in a hydroponic system sample. Considering the results of this present study, the importance of controlling the hygienic and sanitary conditions in the green leafy vegetables can be verified, as well as the adequate sanitation before the raw consumption independently of the system of cultivation. / O consumo de hortaliças tem sido incentivado, visto que dados científicos mostram a presença de características nutricionais associadas a benefícios para a saúde humana. No entanto, a qualidade microbiológica das hortaliças tem despertado interesse e preocupação de pesquisadores, uma vez que hortaliças são veículos de patógenos aos humanos, especialmente agentes parasitários de importância zoonótica. O presente estudo analisou a contaminação parasitológica em alfaces crespas (Lactuca sativa) cultivadas em diversos sistemas de produção (convencional, orgânico e hidropônico), fornecidas por uma cooperativa de produtores da agricultura familiar, situada no município de Presidente Prudente, São Paulo. As coletas foram repetidas em intervalos semanais, durante o período cinco meses, totalizando 180 amostras de hortaliças. As folhas das alfaces foram lavadas com Extran MA 02 a 0.5% e o fluído resultante submetido às técnicas de sedimentação e de centrífugo-flutuação, para recuperação das estruturas parasitárias. A contaminação por enteroparasitos foi observada em todos os sistemas de cultivo, embora, com a maior frequência, em hortaliças cultivadas no sistema hidropônico. Observou-se que do total de 180 amostras, 71 (39,4%) estavam contaminadas por pelo menos uma estrutura parasitária, sendo 34 (18,9%) das alfaces cultivadas no sistema hidropônico, 20 (11,1%) no orgânico e 17 (9,4%) no sistema convencional. Cistos de Entamoeba spp. foram as estruturas parasitárias mais frequentes nas hortaliças, com maior contagem de cistos naquelas produzidas no sistema hidropônico (p=0,003). Outras estruturas parasitárias foram observadas em menor frequência. Ovos/ larvas de trichostrongilídeos foram recuperados nos três sistemas, enquanto que ovos de Strongyloides spp. encontrados nos sistemas convencional e orgânico, e uma larva no sistema hidropônico. Considerando os resultados do presente estudo, verifica-se a importância do controle das condições higiênicos sanitárias de hortaliças, assim como a adequada higienização antes do consumo in natura , independentemente do sistema de cultivo.

This study investigates the economics of water as used by smallholder irrigation farmers in South Africa. The productivity and value of water were estimated with data from two smallholder irrigation schemes: Zanyokwe and Thabina. Production parameters such as fertilisers, seeds, pesticides, equipment, transport, labour, and water were treated as inputs. Various methodologies used to estimate water value, including cost-based approaches, were thoroughly reviewed. The aim was to select the ones with more justification for use in smallholder irrigation sector and also to compare a number of approaches. On a case study basis, three methods were applied: residual valuation method, willingness to pay and cost-based approaches (i.e. accounting costs of O&M). Water productivity and values were then evaluated as per crop, farmer, and scheme. Also, cross-section regression analysis was used to investigate the effect of some key socio-economic factors of production on gross margin and willingness to pay. The results indicated that on average, the value of water varies according to methods, crops, farmers and schemes. In the Zanyokwe scheme, water value estimated by the residual method in cabbage is higher (R1.64 per m3) than the one in dry maize (R0.35 per m3), if intensive and high yield irrigated crops are grown per year. Also, in Thabina, water value for cabbage (R1.14 per m3) outperforms water value for dry maize (R0.02 per m3. This means that there is greater potential in vegetable crops than food grain crops, although the two schemes have different irrigation systems, and such analysis is based on one-year data, which may lack accuracy. Low water valuation is ascribed to low yield and extensive cropping systems, because gross margin per hectare is very low. This signifies the need for expansion in high value crops rather than low value crops. At farm and scheme level, the results were derived by using the Smile database and simulated platform. The Smile platform is a data capturing and a calculation tool. It calculates a number of indicators, economic figures, at scheme and individual farm level, allowing for evaluation of the current situation. The results suggested that at present, the Zanyokwe scheme requires about 1 739 255 m3 of irrigation water per year. The total operational costs (accounting costs of O&M) are about R146 097.42. In other words, supplying 1 m3at farm level will cost R0.084. This implies that if irrigation charges are levied so as to cover O&M costs of the Zanyokwe scheme, the current costs (R0.084) will form only 23% of the average gross margin of R0.37 per m3 used at scheme level. Furthermore, in the Zanyokwe irrigation scheme, the results revealed that the most active and efficient farmers (specialized farmers) can make an average gross margin of R4 105 per ha per year, also achieving the highest water productivity R0.69 in gross margin per m3 consumed. However, in the Thabina scheme, the results indicated that, to supply 1 m3will cost R0.062. Thus, the current water supply costs cover about 56 % of what is earned (i.e. R0.11 per m3 used) at scheme level. Again, the most active farmers (commercially oriented pensioners) are more efficient, with average gross margin of R3 092 per ha per year, also achieving the highest water productivity (R0.53 in gross margin per m3 used). These results suggested that certain smallholder farming systems seem capable of paying for irrigation charges of their respective schemes if they are obliged to do so. As far as willingness to pay (WTP) and cost-based approaches (CBA) are concerned, the results clearly show that the active farmers in the Zanyokwe scheme have lower WTP per m3 (R0.03) than the GM of output (R0.69) per m3 of water used. Also, the accounting cost (R0.084 per m3 of water used) is lower than the GM gained. However, in the Thabina scheme, the situation is quite different. The active farmers are willing to pay R0.19 per m3 of water used. This implies that, if farmers are to pay for the charges in order to cover O&M costs, the farmers in Thabina are ready to pay as much as three times the proposed costs of O&M (R0.062 per m3 of water used), although both the WTP and the accounting cost are lower than GM gained. In these results, it is significant that both the accounting cost and the willingness to pay are lower than the GM per m3 of water used at least in the Zanyokwe scheme. Even though the data were drawn from a sample for one year only, this finding on the perception of farmers has implications for extension and training to improve future productive use. Regarding the findings from cross-section regression analysis, the results for GM (as dependent variable) in general indicated that in the Zanyokwe scheme, only credit affects output positively and significantly. Production costs have significant effect on output, but with a negative correlation. It is striking that all the other factors of production including hired labour show negative and insignificant effects on output. In the Thabina scheme, the most important factors of production in the model are land size (hectare) and production costs (Rand per ha). These two variables influence output positively and significantly. As far as WTP (as dependent variable) is concerned, the results indicated that in the Zanyokwe scheme, it is striking that in all the investigated factors, only credit affects WTP positively and significantly. All other factors are insignificant. Also, gross margin of output per m3, unexpectedly, has displayed a negative and insignificant effect on output. In the Thabina scheme, the results show that the land size per hectare, and gross margin of output per m3 affect WTP positively and significantly. Such results are consistent with the assumptions made in the conceptual framework that a farmer with high gross margin gained at farm level is more likely to pay for water costs than those with poor gross margin. On the basis of these findings, the following recommendations were formulated. Specific policies should include promotion of high value crops and improved varieties of seed for food grain crops (e.g. maize) and vegetables (e.g. cabbage). While improved agronomic practices remain important, there is also potential to increase productivity and profitability of the crops by improving water management practices at the canal-system level, such as better timing of water delivery and increased overall canal-water supplies at the farm level. Finally, from a cost recovery point of view, government should develop a program of cost sharing for capital costs of irrigation development. With regard to inter-sectoral competition, these results highlight that, if inter-sectoral competition is left to uncontrolled market forces may result in smallholder farmers' selling their water rights to sectors which value water at higher levels. To avoid a “liberal trap” such as in the example of Chile (where smallholder farmers "en masse" sold their water rights, resulting ultimately in deeper rural poverty), some form of control/management of water rights transaction involving smallholder farmers is necessary. Finally, the findings of this study can be used in various ways. Since, these values determine the farmer’s ability to pay for water now or in the future, the incentive to use water judiciously will be governed by these values. Secondly, the results can be used to evaluate whether the costs estimated and gross margin per m3 gained at farm level, are in line with the farmers’ willingness to pay. Further work is recommended to clarify these conclusions and provide more policy clarification on the better use of water by smallholder irrigation farmers in South Africa. / Dissertation (MInst.Agrar)--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

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