The composition of the non-starch polysaccharides in sweet potato was determined and their flatulence-inducing potential evaluated. A preparative adaptation of the AOAC enzymatic method was used to isolate the insoluble and soluble non-starch polysaccharides. The insoluble non-starch fraction was mainly cellulose, but contained a substantial amount of hemicellulosic glucose, suggesting the presence of an independent glucan fraction. Relatively small amounts of xylose, galactose, arabinose, mannose, rhamnose and fucose were present. Galactose was the predominant sugar in the soluble non-starch polysaccharide fraction, although substantial quantities of arabinose and mannose were also present. Xylose, rhamnose, glucose and fucose were also present in small quantities. Uronic acids also made up a substantial portion of the soluble non-starch polysaccharides. Appreciable protein and ash were present in both the insoluble and soluble NSP fractions. The in vitro test for gas production using Clostridium perfringens as a test organism showed that both the insoluble and soluble non-starch polysaccharides are potential flatulence-inducers in sweet potato. However, the presence of the hemicellulosic glucans in the insoluble fraction make the latter a more likely candidate for flatus-inducer. / Master of Science

A study was made to determine (1) the influence of plant spacing and nitrogen fertilizer on the yield, percentage of soluble solids, the toughness of the pericarp, and protein content of embryos and kernels of hybrid sweet corn, and (2) the influence of locally on the protein content of field corn varieties. The highest yield and weight of ears of sweet corn are obtained with plants spaced 6 inches apart. Of the three varieties, the medium-late maturing Seneca Chief is more desirable from the standpoint of higher yields and weight of ears. Northern Cross had the lowest number of total ears when grown 9 inches apart, and the other two varieties with 12 inches between plants in the row. Differences in earliness, yield, the weight of ears, and the number of ears per plot are found among the varieties studied. The number of shoots or tillers of Seneca Chief is higher than that of Northern Cross or Seneca Arrow; with increases in spacing the number of shoots per plant increases. The early maturing variety Northern Cross was less desirable in that the kernels at harvest contained a lower percentage of soluble solids, had the toughest pericarp; however, it contained a higher average percentage of total protein (15.31) than either Seneca Arrow (14.50) and Seneca Chief (13.56). Northern Cross also contained a higher average percentage of total protein in the embryos (17.00) than either Seneca Chief (16.44) and Seneca Arrow (14.87). The embryo protein, considered to be more digestible than the protein of the endosperm was not influenced by spacing treatments. Under the conditions of this experiment, there was no association between the amount of nitrogen fertilizer and the percentage of soluble solids, toughness of the pericarp, protein content, and yield of sweet corn. The supply of nitrogen seemed adequate since the corn crop followed a crop of soybeans. Considering the entire experiment, regardless of variety, spacing, and fertilizer levels, the increase in yield decreased the food value of sweet corn in terms of the protein content of the kernels but did not influence the protein content of the embryos this cannot be considered conclusive because of the limited experimental period and small number of hybrid studied. lt was found that the total protein content of kernel: of three field corn varieties grown in Central America varied more between locations than between varieties grown at the same location. The average protein content of the three field corn varieties ranged from 8.44% to 12.12%. Embryos of the field corn varieties contained a higher percentage of total protein than embryos of sweet corn. Thie fact suggests that field corn, which is low in quality from the standpoint of sweetness, contained a higher digestible protein content than sweet corn. / Master of Science

Yeast breads were prepared with three levels of mashed sweet potato pulp and of mung bean flour. Nine combinations of mashed sweet potato pulp (10, 20, 30 percent), and of mung bean flour (4, 8, 16 percent) substitutions for wheat flour were used to determine the acceptability of these enriched breads. Added liquid was adjusted for moisture in sweet potato pulp. Sensory evaluation data was analyzed by analysis of variance to determine the major effective factor on the acceptability of bread. Objective measurements were used to determine bread volume, percent crude nitrogen, percent ether extractable crude fat, and moisture content of the breads. The sensory evaluation results indicated that the bread quality decreased with increase in the amount of mung bean flour; mashed sweet potato pulp did not affect the bread quality except that the highest level (30 percent) has a slight adverse effect on bread texture. The characteristics of all breads made with mashed sweet potato pulp and mung bean flour varied with the amount of substitute ingredient. In general, mung bean flour affected the acceptability of bread and bread quality. Breads made with 20 percent mashed sweet potato pulp and 4 or 8 percent mung bean flour were judged to have more desirable eating quality. Volume of bread was decreased with increase in the amount of mung bean flour and of mashed sweet potato pulp. The percent crude nitrogen increased with the addition of mung bean flour and decreased with the addition of mashed sweet potato pulp. Bread enriched with 16 percent mung bean flour and 10 percent mashed sweet potato pulp increased in the amount of percent crude nitrogen approximately 16.7 percent compared with the control. Percent ether extractable crude fat content of all breads was low and was varied. Moisture content increased with addition of mung bean flour and mashed sweet potato pulp. / Master of Science

Sweet potato single-leaf cuttings of cultivars ‘Centennial,’ ‘Jewel,’ and ‘Nemagold’ were planted in plastic pots containing steam-sterilized sand. Fully opened leaves were counted from the terminal apex on stock plant stems, and leaf positions 1 to 3 and 7 to 9 were referred to as mean leaf positions 2 and 8 respectively. Dry weight and its partitioning among plant organs (leaf, stem, petiole, new shoot, fibrous roots, and stronger roots) differed among the three cultivars. ‘Centennial’ had the highest storage root dry weights in both the first (December-March) and second (April-June) experiments. The new shoots and storage root dry rates of ‘Centennial’ and ‘Jewel’ were 3 to 25 times greater at 79 days after planting (DAP) in the second experiment than at 70 DAp in the first experiment. The new shoot was the dominant sink in ‘Nemagold’ between 28 and 70 DAP in the first experiment but not in the second experiment, and the storage root never became a strong sink in either experiment. A shift from leaf dry weight increases to decrease was observed in the first experiment but not in the second experiment. Leaves in mean leaf position 2 showed higher original plant material (leaf, petiole, and stem) dry weight than mean leaf position 8, but there were no significant differences in final storage root dry weight between these two mean leaf positions in both experiments. Mean leaf positions 2 approximant net assimilation rate (NAR) values based on leaf and new shoot dry weight exceeded mean leaf positions 8 approximate NAR values in both experiments. Plants with stem attachment had higher new shoot and storage root dry weights than plants without stem attachment. Dry weight of the original leaf decreased in plants with steam attachment but not in plants without stem attachment. / M.S.

The object of this paper is to determine the optimum concentration of sulfur dioxide to be used in the commercial dehydration of the sweet potato by this process. Attention has been given to two aspects of the problem, (1) the effect of sulfur dioxide upon the extraction of water from the sweet potato by mechanical means, and (2) the effect of sulfur dioxide upon the stability of the carotene in the sweet potato over a period of several months.

Sweet potato [Ipomoea batatas (L.) Lam] is technically a perennial plant, cultivated and explored as an annual crop. Thus, the identification of the cultivation cycle and sweet potato clones is important for a better utilization of this crop, in both, human and animal nutrition, as for ethanol production. The aim of this work was to evaluate the performance of sweet potato clones grown in different cultivation cycles. The experimental design was a randomized block design, in a split-plot scheme, with three replications. We tested in the plots three cultivation cycles (3, 5 and 7 months), and in the split plots, six sweet potato clones (accessions IBP-007, IBP-038, IBP-075, IBP-079 and IBP-149, and cultivar Brazlândia Rosada). The experiment was carried out at the Research Farm "Campus Rural da UFS", located in the municipality of São Cristovão-SE. The analyzed variables were: survival, damages caused by soil insects, fresh and dry weight of the aerial part, total root yield, content of root dry matter, starch and amylose, and yield of starch and ethanol. All variables were subjected to analysis of variance with the F test, and when significant, the means were compared by the Skott-Knott test at 5% probability. The lowest survival rates occurred in the seventh month of cultivation (51.11%), together with the greatest damage caused by soil insects (4.29), where the clones IPB-038 (2.84), IPB-075 (3.01) and IPB-149 (2.88) showed resistance at the seven month cultivation cycle. Clone IPB-007 presented high values of fresh (14.07 t.ha-1) and dry weight (2.81 t.ha-1) of the aerial part in all the cultivation cycles, presenting also high yield of roots (33.16 t.ha-1), starch (6.63 t.ha-1) and ethanol (4,379 L.ha-1). For content of root dry matter (38.32%) and starch (26.70%), and ethanol yield (176.26 L.t-1), the clone IPB-149 stood out. There was no significant difference in amylose content. The starch content (13.94%) and the yield of roots (7.53 t.ha-1), starch (1.64 t.ha-1) and ethanol (1,034 L.ha-1 and 92.04 L.t-1) were lower for most of the clones evaluated with three months of cultivation. We recommend the use of the cultivation cycle of five months. / A batata-doce [Ipomoea batatas (L.) Lam.] é tecnicamente uma planta perene, plantada e explorada como anual. Sendo assim, a identificação do ciclo de cultivo e de clones de batata-doce é importante para um melhor aproveitamento dessa cultura, tanto na alimentação humana e animal, como para produção de etanol. O objetivo do presente trabalho foi avaliar o desempenho de clones de batata-doce cultivados em diferentes ciclos de cultivo. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas, com três repetições. Foram testados nas parcelas três ciclos de cultivo (3, 5 e 7 meses), e nas subparcelas, seis clones de batata-doce (acessos IBP-007, IBP-038, IBP-075, IBP-079 e IBP-149, e a cultivar Brazlândia Rosada). O experimento foi implantado na Fazenda Experimental Campus Rural da UFS , localizada no Município de São Cristovão-SE. As variáveis analisadas foram: sobrevivência, danos causados por insetos de solos, massa fresca e seca de parte aérea, produtividade total de raízes, teor de matéria seca de raiz, amido e amilose e rendimento de amido e etanol. Todas as variáveis foram submetidas à análise de variância com teste F e, quando significativa, as médias foram comparadas pelo teste de Skott-Knott ao nível de 5% de probabilidade. Os menores índices de sobrevivência ocorreram no sétimo mês de cultivo (51,11%), juntamente com os maiores danos causados por insetos de solo (4,29), onde os clones IPB-038 (2,84), IPB-075 (3,01) e IPB-149 (2,88) apresentaram resistência no ciclo com sete meses. O clone IPB-007 apresentou elevados valores de massa fresca (14,07 t.ha-1) e seca (2,81 t.ha-1) de parte aérea, em todos os ciclos de cultivo, apresentando também, alta produtividade de raiz (33,16 t.ha-1), amido (6,63 t.ha-1) e etanol (4.379 L.ha-1). Já para teor de matéria seca de raiz (38,32%) e amido (26,70%) e rendimento de etanol (176,26 em L.t-1), o clone IPB-149 se destacou. Não houve diferença significativa para o teor de amilose. O teor de amido (13,94%) e o rendimento de raiz (7,53 t.ha-1), amido (1,64 t.ha-1), e etanol (1.034 L.ha-1 e 92,04 L.t-1) foram menores para a maioria dos clones avaliados no ciclo com três meses de cultivo. Recomenda-se usar o ciclo de cultivo de cinco meses.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A cultura da melancia é uma das mais importantes no Estado de Roraima, com uma área plantada de aproximadamente 1000 ha-1 irrigados e produtividade média de 8.017 kg ha-1 de frutos. Essa produtividade é considerada baixa, levando em conta o potencial da cultura; e as razões disso são o manejo inadequado, principalmente, da adubação. Neste estudo, testaram-se três sistemas de sucessão de cultura combinados com seis doses de Nitrogênio com o objetivo de avaliar os benefícios da sucessão das culturas e doses de nitrogênio sobre a produtividade de frutos da melancia. Foram instalados dois experimentos (2010 e 2012) no delineamento de blocos ao acaso no esquema de parcelas subdivididas com quatro repetições. Nas parcelas, testaram-se as sucessões de cultura (mucuna preta, feijão-caupi e vegetação espontânea) e, nas subparcelas, as doses de nitrogênio (0 a 250 kg ha-1). A cultura cv Crimson Sweet foi irrigada por sulcos no espaçamento de 1,0m x 3,5m. Avaliou-se a produtividade de frutos comerciais na área útil das subparcelas (7 plantas), número, porcentagem de frutos, massa média de frutos, sólidos solúveis totais e relação polpa-casca. Os dados foram analisados por anova (p<0,05), e as médias referentes aos efeitos das doses de N foram estimadas por análise de regressão polinomial. As espécies de plantas de cobertura não afetaram a produtividade nem a qualidade de frutos de melancia, independentemente do ano de cultivo. As doses 114,77 e 115,49 kg ha-1 de N proporcionaram o maior número de fruto, (6.900 e 4.889 frutos ha-1) e massa média de frutos (9,49 e 13,15 kg fruto-1), no primeiro e no segundo ano decultivo, respectivamente. A porcentagem de frutos não foi influenciada pelas plantas de cobertura e nem pelas doses de N, independentemente do ano de cultvo. Os sólidos solúveis totais e a relação polpa/casca do fruto de melancia não foram influenciados pelas espécies de plantas coberturas nem pelas doses de N. A maior produtividade de frutos (64,02 e 55,05 Mg ha-1) obtidas com doses de 125,11 e 155,31 kg ha-1 de N, no primeiro e no segundo ano de cultivo, respectivamente. / The watermelon crop is one of the most important in the State of Roraima, with a planted area of approximately 1000 ha-1 and yield of irrigated 8.017 kg ha-1 fruit. This productivity is considered low, taking into account the potential of the crop, and the reasons are inadequate management mainly fertilization. In this study, we tested three systems of succession culture combined with six doses of nitrogen in order to evaluate the benefits of crop succession and nitrogen on fruit yield of watermelon. Two experiments were established (2010 and 2012) in a randomized block design in a split-plot with four replications. In the plots, we tested the crop sequence (velvet bean, cowpea and spontaneous vegetation) and the subplots, the nitrogen levels (0 to 250 kg ha-1). The culture cv Crimson Sweet was irrigated by furrows spaced at 1.0 m x 3.5 m. We evaluated the Commercial fruits in the useful area of the subplots (7 plants), number, percentage of fruits, average fruit weight, soluble solids and pulp-peel. Data were analyzed by ANOVA (p <0.05), and the averages on the effects of N rates were estimated by polynomial regression analysis. The species of cover crops did not affect productivity or quality of watermelon fruits, regardless of the crop year. Doses 114,77 and 115,31 kg ha-1 N gave a higher number of fruit (6900 and 4889 fruits ha-1) and average weight of fruits (fruit 9.49 and 13.15 kg-1), the first and second decultivo years, respectively. The percentage of fruits was not influenced by cover crops and not by N, regardless of the year of cultvo. The total soluble solids and pulp / fruit rind of watermelon were not affected by plant species or coverages by N The highest fruit yield (64.02 and 55.05 Mg ha-1) obtained with doses of 125,11 and 155.31 kg N ha-1, the first and second year of cultivation, respectively.

Sweet potato (Ipomoea batatas Lam.) is ranked as the seventh most important food crop in the world and its large biomass and nutrient production give it a unique role in famine relief. However, multiple virus infection is the main disease limiting factor in sweet potato production worldwide. The main objective of this research project was to develop a transgenic sweet potato cultivar with broad virus resistance in South Africa (SA). A review of current literature assembled background information pertaining to the origin, distribution and importance of the sweet potato crop; viruses and complexes infecting sweet potato; and the strategies used in sweet potato virus detection and control. A survey to determine the occurrence and distribution of viruses infecting sweet potato (Ipomoea batatas Lam.) was conducted in major sweet potato-growing areas in KwaZulu-Natal (KZN). A total of 84 symptomatic vine samples were collected and graft inoculated onto universal indicator plants, Ipomoea setosa Ker. and Ipomoea nil Lam. Six weeks post inoculation, typical sweet potato virus-like symptoms of chlorotic flecking, severe leaf deformation, stunting, chlorotic mosaic, and distinct interveinal chlorotic patterns were observed on indicator plants. Under the transmission electron microscope (TEM), negatively stained preparations of crude leaf sap and ultra-thin sections from symptomatic grafted I.setosa plants revealed the presence of elongated flexuous particles and pinwheel type inclusions bodies‟ that are characteristic to the cytopathology of Potyviruses. Symptomatic leaf samples from graft-inoculated I. setosa and I. nil were assayed for Sweet potato feathery mottle virus (SPFMV), Sweet potato mild mottle virus (SPMMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato chlorotic fleck virus (SPCFV), Sweet potato virus G (SPVG), Sweet potato mild speckling virus (SPMSV), Sweet potato caulimo-like virus (SPCaLV), Sweet potato latent virus (SPLV), Cucumber mosaic virus (CMV), and Sweet potato C-6 virus (C-6) using the nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA). The majority of leaf samples (52%) tested positive for virus disease and showed the occurrence of SPFMV, SPMMV, SPCSV, SPCFV, SPVG, SPMSV, and SPCaLV. Of these 7 viruses, the most frequently detected were SPFMV (39%), SPVG (30%), followed by SPCSV (13%) and SPMMV (12%). SPCaLV and SPCFV at 10% and SPMSV at 7% were found exclusively in samples collected from one area. SPFMV, SPVG, SPCSV, and SPMMV were identified as the most prevalent viruses infecting sweet potato in KZN. The genetic variability of the three major viruses infecting sweet potato (Ipomoea batatas Lam.) in KZN was determined in this study. A total of 16 virus isolates originating from three different locations (Umbumbulu, Umfume and Umphambanyomi River) in KZN were analyzed. These comprised of 10 isolates of Sweet potato feathery mottle virus (SPFMV), five isolates of Sweet potato virus G (SPVG) and one isolate of Sweet potato chlorotic stunt virus (SPCSV). The phylogenetic relationships of the SPFMV, SPVG and SPCSV isolates from KZN relative to isolates occurring in SA and different parts of the world were assessed. The division of SPFMV into four genetic groups (strains) according to the phylogenetic analysis of coat protein encoding sequences revealed mixed infections of the O (ordinary) and C (common) strains in sweet potato crops from KZN. All SPFMV isolates showed close lineage with isolates from South America, East Asia and Africa. The SPVG isolates showed high relatedness to each other and close lineage with other isolates, especially those from China and Egypt. Analysis of the partial sequence of the Heat shock protein 70 homologue (Hsp70h) gene indicated that the SPCSV isolate from KZN belongs to the West African (WA) strain group of SPCSV and showed close relatedness to an isolate from Argentina. The knowledge of specific viral diversity is essential in developing effective control measures against sweet potato viruses in KZN. Multiple virus infections of Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus G (SPVG) and Sweet potato mild mottle virus (SPMMV) cause a devastating synergistic disease complex of sweet potato (Ipomoea batatas Lam.) in KZN. In order to address the problem of the multiplicity and synergism of sweet potato viruses in KZN, this study aimed to develop transgenic sweet potato cv. Blesbok with broad virus resistance. An efficient and reproducible plant regeneration protocol for sweet potato (Ipomoea batatas Lam.) cultivar Blesbok was also developed in this study. The effect of different hormone combinations and type of explants on shoot regeneration was evaluated in order to optimize the regeneration protocol. Coat protein (CP) gene segments of SPFMV, SPCSV, SPVG and SPMMV were fused to a silencer DNA, the middle half of the nucleocapsid (N) gene of Tomato spotted wilt virus (TSWV) and used as a chimeric transgene in a sense orientation to induce gene silencing in the transgenic sweet potato. Transformation of apical tips of sweet potato cv. Blesbok was achieved by using Agrobacterium tumefaciens strain LBA4404 harboring a modified binary vector pGA482G carrying the plant expressible neomycin phosphotransferase ll gene (nptll), the bacterial gentamycin-(3)-N-acetyl-transferase gene and the expression cassette. A total of 24 putative transgenic plants were produced from the transformed apical tips via de novo organogenesis and regeneration into plants under 50mg/L kanamycin and 200 mg/L carbenicillin selection. Polymerase chain reaction (PCR) and Southern blot analyses showed that six of the 24 putative transgenic plants were transgenic with two insertion loci and that all plants were derived from the same transgenic event. The six transgenic sweet potato plants were challenged by graft inoculation with SPFMV, SPCSV, SPVG and SPMMV- infected Ipomoea setosa Ker. Although virus presence was detected using NCM-ELISA, all transgenic plants displayed delayed and milder symptoms, of chlorosis and mottle of lower leaves when compared to the untransformed control plants. These results warrant further investigation under field conditions. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

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)

Sweet sorghum has potential as an energy crop in the Southwest since, compared to corn, it requires less fertilizer and water, is cheaper to grow, and requires less energy to process into ethanol. The purpose of this study is to determine the feasibility of obtaining two crops of sweet sorghum from a single seeding. Two cultivars of sweet sorghum were seeded at early and late dates at the Maricopa Agricultural Center in 2006. Two crops of sweet sorghum were obtained in our study with a short season cultivar Bundle King, but not with the longer season cultivar MMR 327/36. The ethanol yield of Bundle King of 213 gal/acre from two crops planted on April 7 was not significantly greater statistically than the ethanol yield of 162 gal/acre from a single crop planted on June 1. Bundle King is an inherently low yielding variety, as are most short season sweet sorghum cultivars that may be used for double cropping. Thus, the problem with double cropping is identifying a suitable cultivar along with increased harvest costs, despite the advantage of providing a more even supply of feedstock to an ethanol plant.