Thesis (M.A. Agricultural Management (Plant Production)) -- University of Limpopo, 2015 / Tomato (Solanum lycopersicum L.) production had been ranked as the most important commodity in terms of job and wealth creation within the auspices of the National Development Plan (NDP) framework in Limpopo Province. However, soil-borne diseases including plant-parasitic nematodes preclude the successful monoculturing of this commodity and therefore inducing instability in job creation. Generally, after growing a tomato crop for one season in commercial tomato-production systems, the land is being fallowed for 3-5 years under natural grasses. Attempts are being initiated to ensure that during the 3-5 years the land be occupied by an economic alternative crop in order to level off job instability as broadly articulated in the NDP framework. The production of sweet stem sorghum (Sorghum bicolor L.) for ethanol production during the 3-5 years fallowing period could potentially be attractive to commercial tomato-producing famers. Preliminary agronomic evaluations demonstrated that sweet stem sorghum var. ndendane-X1 had attributes to fulfil the identified need. However, the degree of nematode resistance of the variety to Meloidogyne incognita race 2 and M. javanica, which are dominant in Limpopo Province, along with the compatibility of var. ndendane-X1 to phytonematicides used in tomato production had not been documented. The objectives of the study were, therefore, to determine whether sweet stem sorghum var. ndendane-X1: (1) had any degree of nematode resistance to M. incognita race 2 under both greenhouse and microplot conditions, (2) had any degree of nematode resistance to M. javanica under greenhouse conditions, and (3) would be compatible with phytonematicides used in suppression of population densities of xiv Meloidogyne species in tomato production under field conditions. In the greenhouse trials, seeds were sown in 20-cm-diameter plastic pots and each seedling inoculated with 0, 600, 1 000, 1 400, 1 800 and 2 200 eggs and second-stage juveniles (J2s) of M. incognita race 2 or M. javanica. Treatments were arranged in a randomised complete block design (RCBD), with 10 replicates (n = 60). In the microplot trial, seeds were sown in 30-cm-diameter plastic pots and buried 75% deep in a 0.30-m intra-row and 0.25-m inter-row spacing. Treatments, namely, 0, 200, 600, 1 000, 1 400, 1 800 and 2 200 J2s of M. incognita race 2 were arranged in RCBD, with 14 replications (n = 98). In a Meloidogyne-infested field trial, seeds were sown at 0.2-m inter-row and 0.3-m intra-row spacing, with treatments 0, 2, 4, 6, 8 and 10 g nemafric-BG phytonematicide/plant, arranged in RCBD, with 13 replications (n = 78). The degree of nematode resistance was measured using host-status and host-sensitivity, which provide information on reproduction of the target nematode and plant damage due to nematode infection, respectively. Nematode reproduction was measured through the reproductive factor (RF), which is a proportion of final nematode population density (Pf) to initial nematode population density (Pi), summarised as RF = Pf/Pi. In all nematode resistance trials, RF was equivalent to zero, which implied that var. ndendane-X1 was a non-host to both M. incognita race 2 and M. javanica. Additionally, in both greenhouse and microplot trials, sweet stem sorghum var. ndendane-X1 did not suffer any significant damage due to infection by Meloidogyne species. Using nematode-plant relation concepts, sweet stem sorghum var. ndendane-X1 was resistant to M. incognita race 2 and M. javanica under greenhouse and microplot conditions. Under field conditions, nemafric-BG phytonematicide reduced eggs and J2s of Meloidogyne species in root and soil samples xv by 76-85% and 24-65%, respectively, without nematode effect on plant growth, suggesting that nemafric-BG could be integrated with nematode resistance in var. ndendane-X1 to manage nematode population densities. In conclusion, pilot projects where sweet stem sorghum var. ndendane-X1 could be used during the 3-5 years fallowing period in a tomato-sweet stem sorghum crop rotation system should be established to assess: (i) the economics of the proposed cropping system, (ii) the effect of the cropping system on soil-borne diseases, including plant-parasitic nematodes, and (iii) the effect of the cropping system on soil health.

The common tomato of our garden belongs to the natural order Solanaceae and the genus Lycopersicum. The name from lykos, a wolf, and persica a peach, is given to it because of the supposed aphrodisiacal qualities, and the beauty of the fruit. By culture and use it is a vegetable, botanically it is a fruit and among the fruits, it is a berry being indehiscent, pulpy, with one or more seeds that are not stones. Though the tomato was not recognized as a valuable food until about a century ago, its merit is now universally accepted. Often it is referred to as "the poor man's orange" for it is rich in vitamins and in malic and citric acids, possessing besides, a fine appetizing flavor. The popularity of the tomato in man's diet is due to the fact that it is a most rewarding crop for the home garden. It grows well practically everywhere, affording high nutritional values. The demand for and acceptance of fresh tomato fruit is based largely on its nutritional value, flavor, aroma, taste, and other characteristics, such as color and texture. These quality criteria are dependent primarily on the structure and chemical composition of the fruit. The importance of quality in tomatoes beyond that which can be expressed in calories per gram, or even in vitamin content, is generally accepted in the United States. In order to meet this increasing demand throughout the year tomatoes often have to be grown in the greenhouses. Therefore, in commercial greenhouses, the tomato has replaced lettuce as the principal crop and it is likely to remain as an important underglass crop. Flavor is a composite of taste and odor. Odor is produced by many aromatic substances which are present in fruit. Flavor itself is a very complex sensation. The physiological basis of flavor perception is extremely complex and not clearly understood. Flavor chemistry is a comparatively new field of research. Tomato fruit quality is determined mainly by the sugar acid ratio, pectins, color, and flavor. Among these color and flavor are probably the most useful criteria for estimating maturity of tomato fruit. Higher quality is associated with redness of color and prominence of flavor. The flavor of a fruit becomes pronounced when the sugar content is at its maximum and the color of the skin acquires the richest shade. Isolation of volatile components from natural products is often difficult. Typical flavor and aroma of tomato fruit is primarily due to its volatile components. Neither complete analysis for nor synthesis of tomato flavor has been accomplished due to the marathon of problems associated with the extraction, separation, and identification techniques. The primary aim of this investigation was to separate and identify some of the major flavor and aroma components in the developing tomato fruit and also to assess the influence of certain physiological and biochemical changes on the biosynthesis of these components during fruit growth.

Orientador: Marcos David Ferreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-18T02:12:07Z (GMT). No. of bitstreams: 1 Oliveira_SabrinaLeitede_M.pdf: 1086859 bytes, checksum: 722072b7898b25fdeae3007d0e249820 (MD5) Previous issue date: 2011 / Resumo: A grande variação no valor do tomate de mesa, do mesmo grupo varietal, mesma classificação e no mesmo dia de comercialização, registradas no mercado atacadista da Companhia de Entrepostos e Armazéns Gerais de São Paulo (CEAGESP), tem entre suas causas mais importantes a diferença de qualidade entre os atributos destes frutos. O objetivo deste trabalho foi criar uma ferramenta de avaliação dos atributos de qualidade considerados importantes para o tomate de mesa e a partir da avaliação destes atributos apontar os mais relevantes na diferença de valor praticado na comercialização no mercado atacadista de tomate da CEAGESP. Primeiramente, foram levantados a partir da entrevista com agentes de comercialização de tomate da CEAGESP os principais atributos, que determinam a qualidade do tomate de mesa. A partir desta respostas, em uma segunda etapa, foi criado um gabarito visual de avaliação da qualidade a ser utilizado como ferramenta de avaliação das causas da diferença de valor. Por fim, na terceira etapa, foram levantados os lotes de tomate de mesa do grupo Saladete, longa vida de coloração final vermelha, de preço máximo e os de preço mínimo para três classificações (graúdo, médio e miúdo) comercializados no mesmo dia e avaliados os seus atributos de qualidade por dois sistemas: sistema I - avaliação dos atributos de qualidade por meio de notas de desempenho de acordo com o gabarito visual, e o sistema II - levantamento da frequência de ocorrência de cada atributo avaliado no lote de tomate. Os atributos que determinam a qualidade do tomate, segundo os agentes de comercialização de tomate da CEAGESP, são: o tamanho (tipo ou calibre), a coloração do fruto, a ausência de defeitos, durabilidade, embalagem e sabor. Constatou-se que a diferença média entre os preços máximos e mínimos, nos dias levantados, foi maior para o tomate classificado como miúdo (196%), seguido do médio (106%) e graúdo (44%). Os atributos determinantes na explicação da variação de preços avaliados pelo sistema I são embalagens paletizáveis (caixa com dimensões externas que permitam o empilhamento em palete, 1,00 m por 1,20 m, e com furos laterais que permitam a boa circulação de ar) e embalagens que proporcionem um adequado empilhamento (encaixe perfeito das embalagens, suporte adequado do produto pela embalagem, pilha regular e firme), enquanto que, para o sistema II, estes atributos são: frutos sem danos superficiais de casca e proteção adequada da embalagem contra injúrias mecânicas. A metodologia empregada para a valoração dos atributos de qualidade de lotes de tomate de preço máximo e mínimo, com utilização do gabarito visual mostrou ser uma boa ferramenta de gestão da competitividade e de diferenciação de valor / Abstract: The large variation in the value of tomato from the same variety group, same classification and on the same day of marketing, registered by the Terminal Market of the Companhia de Entrepostos e Armazéns Gerais de São Paulo - CEAGESP, were related to the difference in quality between the attributes of those fruits. The main goal of this work was to create a tool for the evaluation of the quality attributes considered important for tomatoes and from the assessment of these attributes target the most relevants for the difference in value practiced during commercialization at CEAGESP. Firstly, based on the interview with the agents of commercialization of tomatoes at CEAGESP, the main attributes seen by them, which determines the quality of tomato were raised. Based on those answers, in a second stage, it was created a gauge visual quality assessment to be used as a differential tool in the process of decision making. In a third stage, the maximum and minimum price for three classifications (big, medium and minute) were raised for lots of tomato group Saladete, long life end red color marketed in the same day and their quality attributes were evaluated for two systems: system I the quality attributes were evaluated, based on banknotes of performance according to the loading gauge visual, and for system II - in addition to the assessment by notes according to the loading gauge visual, the frequency of occurrence of the attribute in a lot of tomato was measured. The attributes that determines the quality of tomato, according to the tomatoes commercialization agents from CEAGESP, are: size (type or size), fruit color, absence of defects, durability, packaging and flavor. It was observed that the average price difference for the three classifications raised in the days of the research was 115.3%. The prices variation was greater for tomatoes classified as small (196%), followed by medium (106%) and big (44%). It was concluded that, for the three classifications, the most important attributes to explain the variation of prices assessed by the system I are packaging that are suitable to be palletized (Box with external dimensions that allow piling in a pallet, 1,00 m 1,20 m, and with lateral holes to enable good air circulation) and packaging that provides an appropriate pile (perfect notch of packages, appropriate support of the produce e by the package, stack regular and steady of piles), on the other hand, for system II, these attributes are: fruit without superficial skin damage and adequate protection of the package against mechanical injuries. The evaluation of quality attributes of tomatoes through the use of visual gauge-assessment showed to be a very efficient tool allowing knowledge to the commercial agents of the more relevant features, and identifying those which need potential investments / Mestrado / Tecnologia Pós-Colheita / Mestre em Engenharia Agrícola

Apesar de sua elevada importância econômica mundial, o cultivo do tomateiro é classificado como de alto risco devido à infestação da cultura por um grande número de pragas e doenças. Esse problema leva tal cultura a depender amplamente da aplicação de agroquímicos que, além de elevaram o custo de produção, são potenciais causadores de danos ambientais e do aparecimento de outras pragas e doenças. Observando o problema mais detalhadamente, pode-se perceber que uma grande parcela das perdas advém dos danos causados por artrópodes herbívoros, os quais são capazes de se alimentar de diversas partes da planta, causando, geralmente, perda de produtividade. Apesar disso, o tomateiro apresenta mecanismos de defesa naturais contra tais pragas, como tricomas e aleloquímicos, que agem intoxicando os artrópodes, dificultando sua movimentação e/ou alterando varias fases de seu desenvolvimento. A busca por genótipos de tomateiro com maior densidade de tricomas e elevado teor de aleloquímicos é hoje considerado um hot spot de pesquisa, devido ao benefício que trariam como redução do custo de produção e maior produtividade. Sabese que vários hormônios vegetais estão ligados a geração de caracteres anti-herbivoria, mas, atualmente, um grande foco vem sendo dado somente ao ácido jasmônico, devido ao seu claro papel na formação de tricomas, aleloquímicos, inibidores de proteases, dentre outros. Visando mostrar a importância de uma abordagem multi-hormonal nesse tipo de estudo, o presente trabalho teve como objetivo avaliar quais hormônios vegetais estão envolvidos com a formação de vários caracteres anti-herbivoria em tomateiro, como densidade de tricomas e teor de aleloquímicos e inibidores de protease. Para tal, fez-se uso da um grande número de mutantes hormonais introgredidos na cultivar Micro-Tom (a qual apresenta diversas facilidades de trabalho como porte reduzido e rápido ciclo de vida). Demonstrou-se que, apesar do ácido jasmônico ser extremamente importante na formação de tais caracteres, outros hormônios também atuam fortemente em tal papel. Etileno, giberelinas e auxina alteram de forma indireta a densidade de tricomas em tomateiro, através de alteração na área de células epidérmicas. O ácido jasmônico é um forte regulador positivo da formação de tricomas, do aleloquímico zingibereno e da formação de inibidores de protease. De forma antagônica, brassinosteróides parecem controlar negativamente a densidade de tricomas, a produção de zingibereno e inibidores de protease. Interessantemente, observou-se que esse controle negativo efetuado por brassinosteróides acontece através de um controle na via do ácido jasmônico, o qual foi comprovado pela produção de duplos mutantes. Resultados obtidos em testes com o herbívoro polífago Spodoptera frugiperda e com a praga de tomate Tuta absoluta (traça-do-tomateiro), bem como de análise de expressão gênica comprovaram a importância do ácido jasmônico, brassinosteróides e sua interação na defesa a herbivoria. Os resultados aqui apresentados sugerem que o foco para futuros estudos da formação de mecanismos anti-herbivoria em tomateiro deve ser voltado não só para o ácido jasmônico como para brassinosteroides e para suas ações antagônicas. / Even though the cultivation of tomato has a high economical importance, this culture is classified as being of elevated risk because of it common infestation by pests and diseases. This problem makes this culture greatly dependent of the application of several agrochemicals, which leads to increase in cost of production, environmental damages and also facilitating the appearance of new pests and diseases. Looking carefully to the problem, it is possible to conclude that a great part of tomato losses are caused by herbivory-arthropods, which are capable of feeding of several parts of the plant, causing, generally, losses in the productivity. However, tomato has natural defense mechanisms against those pests, for example trichomes and allelochemicals, which act poisoning the arthropods, hindering their movement through the plant and/or altering steps of their development. The search for tomato genotypes with great density of trichomes and elevated levels of allelochemicals is nowadays being considered as a hot spot of research, because of the benefits it would provide (for example: a decrease in the cost of production and also a higher productivity). Although it is believed that many plant hormones are involved in the generation of anti-herbivory traits, a great focus has been given only to jasmonic acid because of it clear action in the formation of those traits, such as trichomes, allelochemicals, proteinase inhibitors and many others. The present work objective was to evaluate which hormones are involved in the formation of anti-herbivory traits such as trichome density and allelochemicals and proteinase inhibitors content. For this reason, we made use of several hormonal mutants already introgressed in the Micro-Tom cultivar (which presents benefits as small size and fast life cycle). It was showed that jasmonic acid is an important hormone in the formation of these traits, but other phytohormones also play important roles. Ethylene, gibberellins and auxin alters trichome density indirectly, by altering the area of epidermal cells and thus cell number. Jasmonic acid is a positive regulator of trichome formation, the allelochemicals zingiberene content and also in the formation of proteinase inhibitors. However, brassinosteroids acts by negatively controlling all of those. Interestingly, we observed that this negative control happens through the control of jasmonic acid pathway, a hormonal interaction that was proved by double-mutant analysis. Results obtained in tests with the polyphagous insect Spodoptera frugiperda and the tomato specific pest Tuta absoluta (tomato pinworm) and also with qPCR showed the importance of jasmonic acid, brassinosteroid and their interaction in herbivory defense. Our data suggest that future studies about the formation of antiherbivory traits should be analyzed by focusing the functions not only of jasmonic acid but also brassinosteroid and their antagonist functions.

Thesis (M. Agric. (Plant Protection)) -- University of Limpopo, 2019 / Plant extracts exhibited broad spectrum of activities against root-knot (Meloidogyne species) nematodes and had long been considered as an attractive alternative due to their being biodegradable and posing limited risk hazards to the environment, animal and human health. Additionally, the materials had been dubbed as being of low-input costs and had been viewed as being easy to apply in agricultural systems. The objective of the current study was to investigate the efficacy of paint-brush flower (Kleinia longiflora) either as fermented or granular formulations on suppression of M. javanica and their related effects on growth of tomato (Solanum lycopersicum) plants under field and greenhouse conditions. Fermented crude extracts were applied at 0, 2, 4, 8, 16, 32 and 64%, whereas granular materials were applied at 0, 2, 4, 6, 8, 10 and 12 g. Regardless of the product, the treatments were arranged in randomised complete block design (RCBD), with 12 replications. Kleinia longiflora plants were collected from the wild, chopped into pieces, oven-dried at 52⁰C and fermented in effective microorganisms (EM) for 14 days, whereas the remained were retained for use as granular formulation. Tomato seedlings cv. ꞌFloradadeꞌ were used as test plants inoculated with 2500 eggs and second-stage juveniles (J2) of M. javanica. At 56 days after the treatments, nematode and plant variables were collected, prepared using appropriate methodologies and subjected to analysis of variance using Statistix 10.0 software to generate means. Plant variables were subjected to the Curve-fitting Allelochemical Response Data (CARD) computer-based model to generate appropriate biological indices. Nematode and mineral elements variable means were subjected to lines of the best fit. Findings showed second-stage juveniles (J2) in roots, J2 in soil, eggs and Pf under increasing concentration were highly significant and exhibited negative quadratic relationship. The model explained the associations by 82, xvii 81, 74 and 76%, respectively. In granular formulation, the product had no significant effects on nematode population densities. The fermented crude extracts significantly affected and exhibited positive quadratic relations for dry fruit mass, chlorophyll content, dry shoot mass, number of flowers, plant height, number of fruit and stem diameter of tomato plants. The model explained the relationship by 97, 94, 95, 96, 94, 97 and 96%, respectively. In contrast, in granular formulation, the product had significant effects and positive exhibited quadratic relations on Chlorophyll content under field and greenhouse, plant height, dry root mass and dry shoot mass. The model explained the relationships by 52, 45, 56, 47 and 59%, respectively. Plant variables and increasing concentration of the products exhibited density-dependent growth patterns for both formulations, with overall sensitivity (∑k) values of 1 and 11, respectively. In fermented liquid and granular formulations, the Mean Concentration Stimulation Point (MCSP) values were derived at 1.97% and 2.84 g, respectively. The increasing concentration of fermented K. longiflora also had significant effects and exhibited negative quadratic relations on the accumulation of K, Na and Zn in leaf tissues of tomato plants. The model explained the associations with 87, 94 and 94%, respectively. In conclusion, the findings in the current study suggested that the nematicidal chemicals in K. longiflora could not be released through irrigation water but could be released into solution through microbial degradation. Also, at low concentration suitable for use without inducing phytotoxicity, the products in either formulation could improve the accumulation of certain nutrients in leaf tissues of tomato plants.

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BACKGROUND:Tomato leaf curl Sudan virus (ToLCSDV) is a single-stranded DNA begomovirus of tomato that causes downward leaf curl, yellowing, and stunting. Leaf curl disease results in significant yield reduction in tomato crops in the Nile Basin. ToLCSDV symptoms resemble those caused by Tomato yellow leaf curl virus, a distinct and widespread begomovirus originating in the Middle East. In this study, tomato samples exhibiting leaf curl symptoms were collected from Gezira, Sudan. The associated viral genome was molecularly characterized, analyzed phylogenetically, and an infectious clone for one isolate was constructed.FINDINGS:The complete genomes for five newly discovered variants of ToLCSDV, ranging in size from 2765 to 2767-bp, were cloned and sequenced, and subjected to pairwise and phylogenetic analyses. Pairwise analysis indicated that the five Gezira isolates shared 97-100% nucleotide identity with each other. Further, these variants of ToLCSDV shared their highest nucleotide identity at 96-98%, 91-95%, 91-92%, and 91-92% with the Shambat, Gezira, Oman and Yemen strains of ToLCSDV, respectively. Based on the high maximum nucleotide identities shared between these ToLCSDV variants from Gezira and other previously recognized members of this taxonomic group, they are considered isolates of the Shambat strain of ToLCSDV. Analysis of the complete genome sequence for these new variants revealed that they were naturally occurring recombinants between two previously reported strains of ToLCSDV. Finally, a dimeric clone constructed from one representative ToLCSV genome from Gezira was shown to be infectious following inoculation to tomato and N. benthamiana plants.CONCLUSION:Five new, naturally occurring recombinant begomovirus variants (>96% shared nt identity) were identified in tomato plants from Gezira in Sudan, and shown to be isolates of the Shambat strain of ToLCSDV. The cloned viral genome was infectious in N. benthamiana and tomato plants, and symptoms in tomato closely resembled those observed in field infected tomato plants, indicating the virus is the causal agent of the leaf curl disease. The symptoms that developed in tomato seedlings closely resembled those observed in field infected tomato plants, indicating that ToLCSDV is the causal agent of the leaf curl disease in Gezira.

Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Rhonda R. Janke / The goal of this study is to clarify the influence of organic fertilizer sources on vegetable crop yield under different production systems. This research hypothesized that organic soil amendments will produce healthy and vigorous plants with similar or higher yields while improving soil organic matter levels compared to conventional amendments. Applying organic fertilizer sources can be cost-prohibitive; moreover, synchronizing timing of crop nitrogen demand with soil plant available nitrogen is essential to maximizing yield and reducing nitrogen pollution to the environment. The objectives of this study are to evaluate yield in relation to soil fertility status at different fertility rates for organic and conventional management in field and high tunnel production systems, to measure plant nutrient status in crop petioles and compare it to available mineral N levels in soil at different growing stages, and to determine the effect of nitrogen availability of organic compared to conventional fertilization on plant available nitrogen and crop yield under both systems. A latin square experimental design was conducted from 2008 to 2010 at Kansas State University Research Center in Olathe KS to evaluate an organically managed vegetable rotation of tomato (Solanum lycopersicum L. ‘Bush Celebrity’) and pac choi (Brassica rapa L. ‘Mei Qing’) under three fertility rates; control, low (composted poultry manure), and high (composted poultry manure and fish hydrolyzate) in contrast with conventionally managed soils under two production systems (field and high tunnel). The effect of these four contrasting systems was measured on plant and soil nutrient status. All plots had cover crops of rye during the winter and buckwheat in the summer between pac choi crops. Soil nitrate-N (NO₃-N) and ammonium-N (NH₄-N) were measured, as well as petiole sap nitrate (NO₃⁻). In tomato, additional soluble fertilizers had no direct effect on yield in both field and high tunnel. Compost application had a positive effect on organic matter. In pac choi, additional liquid fertilizer helped organic field plots obtain maximum yield. Soil mineral nitrogen were affected by production system and fertility source, but statistical significance varied by crop and stage. Petiole sap reflected treatment regimens but not necessarily soil N status at each plant stage. The study also addressed long term management practices on organic and conventional available nitrogen. An incubation study on the soil at the conclusion of the field experiment explored the relationship between N mineralization from potentially mineralizable nitrogen (PMN) compared to Illinois Soil Nitrogen Test (ISNT) in control and pre-plant application fertility treatment for both field and high tunnel systems. The results indicated that ISNT concentration values for all soils were below the proposed value for corn crop suggested by (Khan, 2001). ISNT correlated with PMN with the stronger correlation being in field plots. ISNT also correlated with OM in field. Fertility rate showed a significant effect on total carbon and total nitrogen in organic systems of both field and high tunnel plots. This study supports composted poultry manure to improve the fertility status of the soil and to obtain a yield equal to that of conventionally managed soil.