Sweetpotato (Ipomoea batatas) is a major staple food in Africa and the rest of the world where they are discovered to be a good source of carbohydrates, vitamin A, vitamin C and protein. The maximum production potential of the crop is being hampered by severe drought which ravages most parts of Africa. The main aim of this project therefore is to screen collected accessions of sweetpotatofor drought tolerance in a quick screening method with a view to identify cultivars that can perform well under water stress conditions. Fifty selected sweetpotato accessions consisting of cultivars and breeding lines collected from the ARC-VOPI gene bank were planted for drought screening in the glass house for 6 weeks during which water was withheld to induce stress. Observations were made on number of dead plants and days to wilting point, the results were analyzed and 12 best performing cultivars were selected for field trials. The field trial was carried out in Lwamondo, Thohoyandou for 6months under rain-fed conditions. The experiment was conducted in a complete randomized block design with 6 replicates.Yield data and growth parameters were collected every 8 weeks during the trial period and the data collected was analyzed using ANOVA. The best performing cultivars were Zapallo, Tacna, Ejumula, 2004-9-2 and Ndou. They were therefore recommended for further evaluation in other drought prone areas of the country. / Agriculture and  Animal Health / M. Sc. (Agriculture)

The sweet potato (Ipomoea batatas L.) is a dicotyledonous species of Convolvulaceae family, cultivated worldwide, with a low production cost and high economic return. Can be utilized in food and feed and ethanol production. The present study aimed, morphological, agronomic and biochemical characterization of sweet potato from the Active Germplasm Bank of UFS access. The experiment was conducted at the Experimental Farm " Rural Campus " UFS, located in the municipality of São Cristóvão - SE, using a randomized block design with 73 treatments (accessions of sweet potato), and two repetitions. In morpho-agronomic characterization it was found that descriptors sheet provided the variability among accessions. It was also observed that most accessions showed resistance to soil insects. The fresh and dry weight of shoots showed results ranging from 0,45 t ha-1 to 12,16 t ha-1 and 0,17 t ha-1 to 2,71 t ha-1, respectively. For total root yield variable, the values ranged from 1,20 to 10,89 t ha-1. The accessions showed excellent results for the dry root mass averaging 30,77 %. The starch content varied between 11,56 and 27,07 % , the yield of starch per hectare ranged from 0,30 to 2,39 t ha-1 and amylose content showed values between 11,57 to 32,72 %. While the ethanol yield in L ha-1 ranged from 198-1576 L h-1, the ethanol yield on L t-1 had an average of 142,67 L t-1. The results showed that the Active Germplasm Bank of UFS presents a wide phenotypic and genotypic variability, with different skills. / A batata-doce (Ipomoea batatas L.) é uma espécie dicotiledônea da família Convolvulaceae, cultivada em todo o mundo, apresentando um baixo custo de produção e retorno econômico elevado. Pode ser aproveitada na alimentação humana e animal e na produção de etanol. O presente trabalho teve como objetivo, a caracterização morfológica, agronômica e bioquímica de acessos de batata-doce do Banco Ativo de Germoplasma da UFS. O experimento foi conduzido na Fazenda Experimental Campus Rural da UFS, localizada no município de São Cristovão SE, utilizando o delineamento em blocos casualizados, com 73 tratamentos (acessos de batata-doce), e duas repetições. Na caracterização morfo-agronômica verificou-se que os descritores de folha proporcionaram a variabilidade entre os acessos. Observou-se também que a maioria dos acessos apresentou resistência a insetos de solo. A massa fresca e seca de parte aérea apresentou resultados variando de 0,45 t ha-1 a 12,16 t ha-1 e 0,17 t ha-1 a 2,71 t ha-1, respectivamente. Para a variável produtividade total de raízes, os valores variaram de 1,20 a 10,89 t ha-1. Os acessos demonstraram resultados excelentes para o teor de massa seca de raiz com média de 30,77%. O teor de amido variou entre 11,56 e 27,07%, o rendimento de amido por hectare ficou entre 0,30 a 2,39 t ha-1 e o teor de amilose apresentou valores entre 11,57 a 32,72 %. Enquanto que o rendimento de etanol em L ha-1 variou entre 198 a 1.576 L ha-1, o rendimento de etanol em L t-1 apresentou média de 142,67 L t-1. Os resultados mostraram que o Banco Ativo de Germoplasma da UFS apresenta uma grande variabilidade fenotípica e genotípica, com diferentes aptidões.

No description available.

M. Tech. (Biotechnology, Department of Biotechnology, Faculty of applied and computer sciences) Vaal University of Technolog / Sweetpotato (Ipomoea batatas) is an important food crop that is grown in many countries. A number of viral and fungal sweetpotato diseases have been reported worldwide. One of the major and most economic diseases of the sweetpotato is Alternaria blight which is caused by the fungal pathogen Alternaria bataticola. This disease can be managed in a short term using fungicides and cultural practices. However, a long term and inexpensive approach is through the development of resistant cultivars. A prerequisite to this approach is the knowledge of the genetic diversity of this fungal pathogen. This study assessed the genetic diversity of 25 South African isolates of A. bataticola from naturally infected leaves and stems collected from different sweetpotato growing regions in South Africa by (i) characterising the isolates based on their morphology (ii) pathogenicity tests (iii) random amplified polymorphic DNA (RAPD) (iv) variation of the ITS2 sequences and (v) prediction of the ITS2 secondary structures. The isolates revealed some variation in colony colour pigments after culturing but Koch’s postulates were confirmed by their pathogenicity tests. The analysis of RAPD and variation of the ITS2 sequences showed high levels of variation (100%) among the isolates. Dendrograms generated from these analyses had many subclusters and did not cluster the isolates according to their geographic origins. The ITS2 secondary structures were predicted and can be used to identify and distinguish the isolates. This information in addition to the genetic diversity of the A. bataticola isolates will aid plant breeders in the development of resistant sweetpotato cultivars and early management of blight disease in South Africa.

Field experiments were conducted during the 1989 dry season (July to December) at the Manggoapi Farm of the Faculty of Agriculture, Cenderawasih University in Manokwari, Irian Jaya, Indonesia. The objectives of the experiments were to determine the effects of four sweet potato cropping systems on the population density of sweet potato weevils (SPW) and on the diversity of other insects within these agroecosystems. / Fewer SPW were found in intercropped sweet potato + corn (2 weevils per kg infected tubers), sweet potato + soybean (21 weevils), sweet potato + corn + soybean (8 weevils) than in monoculture sweet potato (37 weevils); percentage of damaged tubers followed the same trend, ranging from 2.6% to 14.0% in intercropped sweet potato, to 21.9% in the sweet potato monoculture. However, the higher number of SPW and damaged tubers in the monoculture did not reduce yield below that in the intercropped plots. / Insect and spider populations were more diverse in the intercropped sweet potato systems than in monoculture. Number of arthropods increased throughout the growing season. Intercropping may reduce the population density of other insect pests associated with sweet potato and may increase the population density of natural enemies.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

Thesis (M.S.)--Mississippi State University. Department of Entomology and Plant Pathology. / Title from title screen. Includes bibliographical references.

Orientador: Cláudio Cabello / Banca: Fernando Broetto / Banca: Paulo Cesar Razuk / Banca: Ivo Mottin Demiate / Banca: Celia Maria Landi Franco / Resumo: As maltodextrinas sao produtos da hidrolise parcial do amido e tem sido largamente usadas nas industrias de alimentos em muitos tipos de alimentos processados. Maltodextrinas sao classificadas de acordo com o grau de hidrolise do amido, que e expressa em dextrose equivalente (DE). Varias propriedades funcionais, como docura, solubilidade e viscosidade variam de acordo com a degradacao enzimatica e a fonte botanica do amido, e somente a caracterizacao pela dextrose equivalente (DE) se tornou inadequada para orientar a utilizacao das maltodextrinas em varias aplicacoes. Levando em consideracao a importancia das maltodextrinas para o mercado de alimentos, o presente trabalho teve como objetivo realizar estudos sobre o processo de producao e o comportamento das maltodextrinas de mandioca e batata-doce e tambem de compara-las com produtos comerciais. Os amidos das referidas tuberosas foram analisados quanto as suas caracteristicas fisico-quimicas, difracao de raios-X e microscopia optica e eletronica de varredura. Suspensoes de amidos de mandioca e batata-doce, a concentracao de 30%, foram submetidas a hidrolise enzimatica pela enzima ¿-amilase em um reator a diferentes tempos de hidrolise e diferentes niveis de agitacao. Em seguida, foram secas em gspray dryerh e analisadas quanto as suas propriedades fisicas e quimicas, funcionais, reologicas e por difracao de raios-X, alem de serem observadas em microscopio eletronico de varredura. A analise das variaveis do processo indicou maior influencia do tempo de hidrolise na dextrose equivalente (DE) das maltodextrinas de mandioca e batata-doce, sendo que a interacao, tempo de hidrolise e agitacao influenciou na sua solubilidade e viscosidade. As maltodextrinas de mandioca e batata-doce apresentaram DE que variaram de 5,5 a 11,3 e 17,0 a 22,9, respectivamente. As maltodextrinas apresentaram alta solubilidade em... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Maltodextrins are obtained from partial hydrolysis of the starch, and have been widely used in industries due to their broad usage in processed food. Maltodextrins are classified by degree of hydrolysis of starch, which is expressed by dextrose equivalent (DE). Many of their functional properties, like sweetness, solubility and viscosity vary according to enzymatic degradation and botanic source of the starch. Due to the wide uses, dextrose equivalent becomes inadequate to predict the efficiency of maltodextrins in many applications. Considering the importance of maltrodextrins for the food market, the objective of this work was to study the production process and the behavior of cassava and sweet potato maltodextrins, as well as compare them with commercial products. Starches of each tuber were analyzed as to their physiochemical characteristics, X-ray diffraction and optic and scanning electron microscopy. Cassava and sweet potato starches suspensions at 30% concentration underwent enzymatic hydrolysis by an á-amylase enzyme in a reactor considering different times of hydrolysis and levels of agitation. Next, starches were spray dried and analyzed as to their physiochemical, functional, rheological properties and X-ray diffraction, as well as scanning electron microscopy observation. Process variables analysis indicated higher influence of the hydrolysis time in the dextrose equivalent (DE) of sweet potato and cassava maltodextrins, the interaction of between hydrolysis time and agitation influencing in the solubility and viscosity. Cassava and sweet-potato maltodextrins presented DE varying from 5.5 to 11.3 and 17.0 to 22.9, respectively. Maltodextrins presented water solubility in all studied conditions and viscosity was influenced by the hydrolysis level and concentration of the solution. A Newton behavior has been observed in cassava and sweet potato maltodextrins... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2014-06-11T19:31:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-01-06Bitstream added on 2014-06-13T21:02:45Z : No. of bitstreams: 1 coutinho_apc_dr_botfca.pdf: 1436935 bytes, checksum: c72f0d2f7b757dff306112676604e8cc (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As maltodextrinas sao produtos da hidrolise parcial do amido e tem sido largamente usadas nas industrias de alimentos em muitos tipos de alimentos processados. Maltodextrinas sao classificadas de acordo com o grau de hidrolise do amido, que e expressa em dextrose equivalente (DE). Varias propriedades funcionais, como docura, solubilidade e viscosidade variam de acordo com a degradacao enzimatica e a fonte botanica do amido, e somente a caracterizacao pela dextrose equivalente (DE) se tornou inadequada para orientar a utilizacao das maltodextrinas em varias aplicacoes. Levando em consideracao a importancia das maltodextrinas para o mercado de alimentos, o presente trabalho teve como objetivo realizar estudos sobre o processo de producao e o comportamento das maltodextrinas de mandioca e batata-doce e tambem de compara-las com produtos comerciais. Os amidos das referidas tuberosas foram analisados quanto as suas caracteristicas fisico-quimicas, difracao de raios-X e microscopia optica e eletronica de varredura. Suspensoes de amidos de mandioca e batata-doce, a concentracao de 30%, foram submetidas a hidrolise enzimatica pela enzima ¿-amilase em um reator a diferentes tempos de hidrolise e diferentes niveis de agitacao. Em seguida, foram secas em gspray dryerh e analisadas quanto as suas propriedades fisicas e quimicas, funcionais, reologicas e por difracao de raios-X, alem de serem observadas em microscopio eletronico de varredura. A analise das variaveis do processo indicou maior influencia do tempo de hidrolise na dextrose equivalente (DE) das maltodextrinas de mandioca e batata-doce, sendo que a interacao, tempo de hidrolise e agitacao influenciou na sua solubilidade e viscosidade. As maltodextrinas de mandioca e batata-doce apresentaram DE que variaram de 5,5 a 11,3 e 17,0 a 22,9, respectivamente. As maltodextrinas apresentaram alta solubilidade em... / Maltodextrins are obtained from partial hydrolysis of the starch, and have been widely used in industries due to their broad usage in processed food. Maltodextrins are classified by degree of hydrolysis of starch, which is expressed by dextrose equivalent (DE). Many of their functional properties, like sweetness, solubility and viscosity vary according to enzymatic degradation and botanic source of the starch. Due to the wide uses, dextrose equivalent becomes inadequate to predict the efficiency of maltodextrins in many applications. Considering the importance of maltrodextrins for the food market, the objective of this work was to study the production process and the behavior of cassava and sweet potato maltodextrins, as well as compare them with commercial products. Starches of each tuber were analyzed as to their physiochemical characteristics, X-ray diffraction and optic and scanning electron microscopy. Cassava and sweet potato starches suspensions at 30% concentration underwent enzymatic hydrolysis by an á-amylase enzyme in a reactor considering different times of hydrolysis and levels of agitation. Next, starches were spray dried and analyzed as to their physiochemical, functional, rheological properties and X-ray diffraction, as well as scanning electron microscopy observation. Process variables analysis indicated higher influence of the hydrolysis time in the dextrose equivalent (DE) of sweet potato and cassava maltodextrins, the interaction of between hydrolysis time and agitation influencing in the solubility and viscosity. Cassava and sweet-potato maltodextrins presented DE varying from 5.5 to 11.3 and 17.0 to 22.9, respectively. Maltodextrins presented water solubility in all studied conditions and viscosity was influenced by the hydrolysis level and concentration of the solution. A Newton behavior has been observed in cassava and sweet potato maltodextrins... (Complete abstract click electronic access below)