The effect of boron deficiency was studied in tomato plants grown hydroponically. Morphological studies showed that boron deficiency in the root system caused a cessation of root elongation, browning and thickening of root tips, the formation of branch roots close to the apex and decrease in the overall size of the root. The pyrimidine biosynthetic pathway remained intact and functional under boron limitation. The sugar nucleotide, uridine diphosphate glucose, was diminished in boron deficient medium and its level was restored to that of born sufficiency when uracil, cytosine, uridine, cytidine or orotic acid was provided.

Shortly after the discovery of the usefulness of chelating compounds by agriculturists, whereby metallic cations are supplied in available form to plants, another use was proposed. This paper is dedicated to this resulting use, namely, that certain chelates appear to have value in keeping phosphate compounds from becoming “fixed” or “tied-up” in the soil.

No description available.

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.

The microbial life in the soil is essential for providing a functioning habitat for plants to grow. A literature study was conducted to investigate the knowledge and science behind soil biology. The purpose of this study was to define what is soil health and how it is influenced by the soil microbial communities. The literature study concluded that the ability of soil biology to benefit plants includes a variety of aspects. Nutrient availability, soil structure and pest resistance are all greatly influenced by soil microbes.  To practically examine these theories, an experiment was conducted where Brandywine tomatoes where grown in three different scenarios. A commercial potting soil, Hasselfors ekojord, was used as substrate in all groups. In the control group (C) the plants were grown only in the substrate. In the second group (R), the seeds where treated with a microbial inoculum and then planted in the substrate. In the third group (RE), the same treatment as in R was done to the seeds and here, compost extract were also added to the RE group. The plants were grown in separate pots in a greenhouse and the growth rate was observed and documented as well as the total harvest. In the end of the growing season a chemical and biological analysis was done to the soil as well as a sap analysis on the leaves. The plant growth where similar among the groups although R and RE showed slightly higher growth rates in the later stages of the growing season. The harvested fruit was highest in C but not significantly. The microbial contents were high in all soils though more fungi communities in the RE and bacterial communities in C. The chemical analysis showed high nitrate concentrations in the leaves in C. In R and especially RE the nitrate conversion into amino acids and proteins where higher wish indicates that these groups are more resilient to pests like aphids. / Det mikrobiella livet i jorden är avgörande för att skapa en fungerande livsmiljö för växter. En litteraturstudie genomfördes för att undersöka nuvarande kunskap och vetenskap bakom markbiologi. Syftet med denna studie var att definiera markhälsa och hur den påverkas av det mikrobiella livet i jorden. Slutsatsen från denna litteraturstudie var att jordbiologins förmåga att gynna växter innefattar en rad olika aspekter. Näringstillgänglighet, markstruktur och skadedjursbeständighet påverkas starkt av jordmikrober.  För att praktiskt granska dessa teorier genomfördes ett experiment där Brandywine-tomater odlades i tre olika scenarier. En kommersiell plantjord, Hasselfors ekojord, användes som huvudsubstrat i alla grupper. I kontrollgruppen (C) odlades växterna endast i substratet. I den andra gruppen (R) behandlades frön med en mikrobiell ympning innan de såddes i substratet.I den tredje gruppen (RE) utfördes samma fröbehandling som i R och kompostextrakt tillsattes också till RE-gruppen. Växterna odlades i separata krukor i ett växthus och tillväxthastigheten observerades och dokumenterades liksom den totala skörden. I slutet av växtsäsongen gjordes en kemisk och biologisk analys av jorden samt en savanalys på bladen. Tillväxten var likartad bland grupperna även om R och RE visade något högre tillväxttakt i de senare stadierna av växtsäsongen. Skördad frukt per planta var högst i C, dock intesignifikant. Den mikrobiella koncentrationen var hög i alla jordar men mer svamporienterat i RE och bakterieorienterat i C. Den kemiska analysen visade högt nitratinnehåll i bladen i C. I R och särskilt i RE var nitratomvandlingen till aminosyror och proteiner högre vilket indikerar att dessa grupper är mer motståndskraftiga mot skadedjur så som bladlöss.

Climate change is expected to increase the frequency of mild winters and warm springs, which can induce premature plant development. This premature development results in a high risk of exposure of young plant tissues to cold stress leading to severe reductions in plant growth and agricultural production. Plants are associated with complex bacterial communities that can activate acclimation processes and positively affect plant performance at low temperatures. Beneficial effects of plant colonization by cold-tolerant bacteria include the modulation of cold-related genes and the reduction in cellular damage under cold stress, but scarce information is available on mechanisms stimulated by bacterial endophytes in tomato plants against cold stress. The aims of this work were i) to analyze the taxonomy and potential functions of plant-associated microbial communities in cold regions, ii) to understand metabolic changes stimulated by cold-tolerant endophytic bacteria in tomato plants exposed to cold stress, and iii) to identify possible genomic traits of cold-tolerant endophytic bacteria responsible for plant growth promotion and cold stress mitigation. The first chapter includes an introduction on cold stress and acclimation processes in plants, and the second chapter defines the aims of the project. In the third chapter, the taxonomic and functional characterization of plant-associated microbial communities of alpine, Arctic, and Antarctic regions was reviewed, highlighting the main environmental factors affecting their taxonomic structure. e. The key findings of this chapter are the functional roles of microbial communities in plant growth and survival in cold environments, and the suggestion of potential biotechnological applications of ubiquitous and endemic cold-tolerant microorganisms. In the fourth chapter, metabolic changes stimulated by cold-tolerant endophytic bacteria in tomato plants exposed to cold stress were studied by metabolomic analyses, and compounds possibly associated with cold stress mitigation were found. 14 Tomato seeds were inoculated with two bacterial endophytes isolated from Antarctic Colobanthus quitensis plants (Ewingella sp. S1.OA.A_B6 and Pseudomonas sp. S2.OTC.A_B10) or with Paraburkholderia phytofirmans PsJN, while mock-inoculated seeds were used as control. The metabolic composition of tomato plants was analyzed immediately after cold stress exposure (4°C for seven days) or after two and four days of recovery at 25°C. Under cold stress, the content of malondialdehyde, phenylalanine, ferulic acid, and p-coumaric acid was lower in bacterium-inoculated compared to mock-inoculated plants, indicating a reduction of lipid peroxidation and the stimulation of phenolic compound metabolism. The content of two phenolic compounds, five putative phenylalanine-derived dipeptides, and three further phenylalanine-derived compounds was higher in bacterium-inoculated compared to mock-inoculated samples under cold stress. Thus, the presented work suggests that psychrotolerant endophytic bacteria can reprogram polyphenol metabolism and stimulate the accumulation of secondary metabolites, like 4-hydroxybenzoic and salicylic acid, which are involved in cold stress mitigation, and phenylalanine-derived dipeptides possibly involved in plant stress responses. In the fifth chapter, functional and genomic traits of Ewingella sp. S1.OA.A_B6 and Pseudomonas sp. S2.OTC.A_B10 were studied. In the framework of the present study, Ewingella sp., Pseudomonas sp., and the bacterial consortium showed plant growth-promoting activity on tomato seedlings at low temperatures. Ammonia was produced by both bacterial isolates and their consortium, while indole-3-acetic acid and proteases were produced by Ewingella sp. and Pseudomonas sp., respectively. Ewingella sp. and Pseudomonas sp. genomes (51.57% and 60.63% guanine-cytosine, 4,148 and 5,983 predicted genes, respectively) encompassed genes related to amino acid metabolism, plant hormone metabolism (auxin, cytokinins, ethylene, and salicylic acid), nitrogen metabolism, lytic activities (amylases, cellulases, and proteases). Traits related to plant growth promotion included genes for iron transport, phosphate metabolism, potassium transport, siderophore metabolism and 15 transport, and zinc transport. Moreover, Ewingella sp. and Pseudomonas sp. encompassed genes related to cold tolerance, such as cold shock and heat shock-related proteins, lipid desaturases, and genes related to polyamine metabolism, proline metabolism, proline and glycine betaine transport, reactive oxygen species detoxification, and trehalose metabolism. Thus, in this chapter, it was discovered that Antarctic cold-tolerant endophytes include multiple genomic and functional traits to survive under cold conditions and some of them can contribute to promote the host plant growth at low temperatures. These findings indicate that plant-associated bacteria of cold regions have a great biotechnological potential to mitigate cold stress in crop plants. In particular, Antarctic bacterial endophytes encompass genomic traits responsible for plant growth promotion and protection against cold stress, and they can mitigate cold stress in tomato plants by a complex reprogramming of plant metabolism. Although further metabolomic and functional studies are required to verify compound annotations and to better clarify the role of phenylalanine-derived compounds and phenylalanine-derived dipeptides in cold stress mitigation, these results provided a better understanding of metabolic changes stimulated by psychrotolerant endophytic bacteria in cold-stressed tomato plants. Thus, the validation of cold stress mitigation activated by psychrotolerant endophytic bacteria under field conditions will pave the way for the further development of endophytic bacterial inoculants as sustainable products to protect crops against cold stress.

Some plant-beneficial bacteria with biopesticide potential produce antimicrobial compounds that are tightly involved in multitrophic interactions occurring in the phytosphere among which antagonism toward a diverse range of phytopathogens. However, there is a crucial need for an accurate assessment of antibiotic production rate in this environment colonized by these bacteria. In this context, we conducted the present thesis work with the scope to better understand how two different Bacillus genus strains produce lipopeptides in the rhizosphere of plants. In the first part, one of the strains (B. amyloliquefaciens S499) was selected out of other isolates for its technological traits and in vitro inhibition growth activity of plant pathogenic fungi. We further demonstrated its biocontrol potential in tomato open-field experiments where plantings have been devastated by a local fungus preliminary identified as Fusarium semitectum. In a second part, we combined two mass spectrometry-based approaches (electrospray ionization and imaging) to analyze the pattern of surfactin, iturin and fengycin lipopeptide families produced in planta by strain S499. Our results show that rhizosphere conditions are conducive for surfactin synthesis but not for other types of lipopeptides and that the lipopeptide pattern can be markedly influenced by nutritional factors, biofilm formation and oxygen availability. In a last part, surfactin gene expression (srfA) level was evaluated in situ on tomato root using the reporter gene (LacZ) inserted in B. subtilis strain BGS3. Results showed effective expression of srfA and production of surfactin in biologically important level quantities upon establishment of bacterial population on roots. Our results also demonstrate that BGS3 developing in colonies, efficiently utilizes the main substrates from plant exudates to produce surfactins. The production may also be favored in bacteria growing slowly in the rhizosphere. Globally, this work contributes to better appreciate the impact of some environmental factors on the in situ biosynthesis of lipopeptides by strains of Bacillus which is probably an essential step for improving the level and reliability of their efficacy as biological agents for the control of plant diseases.

Thesis (M. A. Agriculture (Plant Protection)) -- University of Limpopo, 2019 / The influence of cultural practices can be modified by environmental conditions such as container-type or positioning. The objective of the study was to determine whether container-type and positioning would have an influence on the growth of tomato plants and suppression of Meloidogyne javanica exposed to biomuti (Trial 1) and Afrikelp (Trial 2). Different container-types were filled with approximately 10.4 L growing mixture comprising steam-pasteurised sandy loam soil and Hygromix-T at 3:1 (v/v) ratio. The containers were established in microplots at 0.6 m × 0.6 m spacing, with treatments being brown pot-below; brown pot-above, black pot-below, black pot-above, plastic bag-above and plastic bag-below. Tomato (Solanum lycopersicum L.) cv. 'Floradade' seedlings were each transplanted and irrigated with 500 ml chlorine-free tapwater every other day. Seven days after transplanting, each plant was inoculated with 2000 eggs and second-stage juveniles (J2) of M. javanica. Biomuti and Afrikelp, obtained from the Agricultural Research Council (ARC) Vegetable, Ornamentals and Plants (VOP), were applied in separate trials weekly at 2.5%. At 56 days after inoculation, plant growth including selected nutrient elements and nematode variables were measured. Data were subjected to analysis of variance, with separation of means achieved using Fisher’s Least Significant Difference test at the probability level of 5%. In the biomuti trial, container-type and positioning had a significant effect on plant height, fruit number, dry root mass, dry shoot mass and fruit mass, contributing 82, 48, 44, 85 and 89% in total treatment variation (TTV) of the respective variables. Relative to brown pot-below; black pot above, plastic bag-above and brown pot-above reduced plant variables, whereas treatment effects were not significant on nematode variables. In the Afrikelp trial, trends where similar to those in biomuti, treatments had highly significant effects on xvi plant height, dry root mass, dry shoot mass and gall rating, contributing 91, 88, 66 and 60% in TTV of the respective variables. Relative to brown pot-below; black pot above, plastic bag-above and brown pot-above reduced the plant variables, but had no significant effects on nematode variables. Generally, plastic bags and polyethylene pots below-ground improved most plant growth variables when compared to those in containers positioned above-ground.

Made available in DSpace on 2015-03-26T13:30:44Z (GMT). No. of bitstreams: 1 texto completo.pdf: 301316 bytes, checksum: 99cd4e8684305bf084ac2f725463bae5 (MD5) Previous issue date: 2012-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Plants protect themselves against herbivore attacks by a combination of constitutive and induced defenses, which reduce the performance of herbivores and decrease the spread of damage. Plants under attack by herbivores release a variety of organic volatile compounds, which are involved in the attraction of natural enemies of herbivores. The natural enemies such as predatory mites and coccinellids, for example, are able to exploit these volatiles to locate their prey, using them as chemical signals for the presence of food. Thus, behavioral studies are important for understanding the interactions that occur between organisms in a food web. As well as the knowledge of the chemical compounds that mediate the location of plants infested with herbivores by natural enemies, in order to have a better understanding of insect-plant interactions mediating the third trophic level. In this study, we investigated the responses of the predators Phytoseiulus longipes, Phytoseiulus macropilis and Cycloneda sanguinea to volatiles from tomato plants infested or not infested with the phytophagous mites Tetranychus evansi or Tetranychus urticae. The main objective was to verify whether these predators are able to discriminate between sources of odors produced by the plant-herbivore complex. We also identified the volatile compounds emitted by plants infested with T. evansi, T. urticae and clean tomato plants. To access these results were used techniques of olfactometry for behavioral tests and GC-MS to identify the compounds. The results show that the tested predators are able to discriminate between volatile tomato plants infested with T. evansi or T. urticae and volatile of clean plants, showing that the plant-herbivore complex releases odors attractive to these natural enemies. But when given the choice between plants infested with T. evansi and plants infested with T. urticae, the predators are not able to discriminate between the two sources of odors produced. The identification of volatile compounds was verified that when comparing clean plants and plants infested with T. evansi or T. urticae was found and identified more volatile compounds in infested plants. When we compare plants infested with T. evansi and plants infested with T. urticae, the profile of the volatile compounds were very similar in both. As for the quantitative analysis of compounds, we found no significant difference between the concentrations of each compound emitted by plants infested with T. evansi and T. urticae. The results obtained through the identification and quantification of volatile compounds may explain the responses obtained in the olfactometer experiments. / As plantas se protegem contra o ataque de herbívoros através da combinação de defesas constitutivas e/ou induzidas que reduzem o desempenho dos herbívoros e, consequentemente, interrompem a propagação do dano. Plantas sadias ou sob o ataque de herbívoros liberam uma variedade de compostos orgânicos voláteis, os quais estão envolvidos na atração dos inimigos naturais desses herbívoros. Os inimigos naturais como ácaros predadores e coccinelídeos, por exemplo, são capazes de explorar esses voláteis para localizar suas presas, usando-os como sinais químicos da presença do alimento. Dessa forma, estudos de comportamento são importantes para o entendimento das interações que ocorrem entre os organismos em uma teia alimentar. Assim como o conhecimento dos compostos químicos que mediam a localização de plantas infestadas com herbívoros pelos inimigos naturais, para que se tenha uma melhor compreensão da interação inseto-planta influenciando o terceiro nível trófico. Diante disso, este trabalho objetivou investigar as respostas dos ácaros predadores Phytoseiulus longipes e Phytoseiulus macropilis e de joaninhas da espécie Cycloneda sanguinea aos voláteis de plantas de tomate infestadas ou não com Tetranychus evansi e Tetranychus urticae. O principal objetivo foi verificar se estes predadores são capazes de discriminar entre as fontes de odores produzidas pelo complexo planta-herbívoro. Nós também identificamos os compostos voláteis emitidos por plantas infestadas com o ácaro-vermelho T. evansi e com o ácaro rajado T. urticae e de plantas de tomate limpas. Para acessar esses resultados foram utilizadas as técnicas de olfatometria para os testes comportamentais e o GC-MS para a identificação dos compostos. Os resultados mostram que os predadores testados são capazes de discriminar entre voláteis de plantas de tomate infestadas com T. evansi ou T. urticae e voláteis de plantas limpas. Isso mostra que o complexo planta-herbívoro libera odores atraentes a estes inimigos naturais. Porém, quando dada à escolha entre plantas infestadas com T. evansi e plantas infestadas com T. urticae, os predadores não são capazes de discriminar entre as duas fontes de odores produzidas. Quanto à identificação dos compostos foi verificado que ao compararmos plantas limpas e plantas infestadas, seja com o ácaro-vermelho ou com o ácaro rajado, foram encontrados e identificados uma quantidade bastante superior de compostos voláteis nas plantas infestadas. Já quando comparamos plantas infestadas com T. evansi e plantas infestadas com T. urticae, o perfil de compostos voláteis encontrado em ambas foi bastante similar. Quanto à análise quantitativa dos compostos, observamos que não existe diferença significativa entre as concentrações de cada composto emitidos por plantas infestadas com T. evansi e T. urticae. Os resultados obtidos através da identificação e quantificação dos compostos voláteis podem explicar as respostas obtidas nos experimentos de olfatômetro.

The use of treated waste water for irrigation of vegetable crops is on the increase in Botswana especially in the Glen Valley farms, a peri-urban settlement of Gaborone city. However, the effects of this practice on heavy metals uptake by vegetable crops are uninvestigated. Chromium and nickel have been reported to be accumulating in Gaborone crop soils and cultivating vegetables in these soils with treated waste water could potentially lead to an increased bio-availability of the heavy metals in the vegetable crops. The main aim of this study was therefore to compare the uptake of chromium and nickel in tomato plants, a vegetable grown in sludge amended Glen Valley soils, to those grown in sludge absent Glen Valley soils using treated waste water at different pH values and tap water for irrigation. The high water uptake and high water consumption rate of tomato plants made it suitable for this study. Twenty five pots each containing 2.5 kg sludge amended Glen Valley soils and 5 pots each containing 2.5 kg sludge absent soils were utilized. Fresh treated waste water in a 50 L plastic container on a need by need basis was used. For the control experiments 5 pots each containing 2.5 kg standard commercial soils and fresh tap water were used. The potted tomato plants were cultivated from early May to middle of October 2009. One leaf and one fruit from each tomato plant was harvested and tested in this study. The highest uptakes of chromium (0.819 mg/L) and nickel (0.327 mg/L) were experienced in the leaves where the tomato plant were cultivated in standard commercial soil and irrigated with tap water at pH 7.0. The least uptake of chromium (0.052 mg/L) and that of nickel (-0.030 mg/L) was found in the fruits, where the tomatoes were grown in sludge amended Glen Valley soil and irrigated with normal Glen Valley treated waste water at pH 8.5. Increasing the pH of the treated waste water from 5.0 to 6.0 caused increased bio-accumulation of chromium and nickel in the leaves and the fruits of the tomato plants. Normal treated waste water (pH 8.5) and treated waste water at pH 9.0, however, reduced the chromium and the nickel uptake by the tomato plants. Treated waste water at pH 10.0 bio-accumulate more chromium and more nickel in the leaves and fruits of tomato plants. The pH variation experiments suggested that the fruit tissues accumulated more chromium and the leaf tissues accumulated more nickel. The mean chromium uptake in the tomato plants exceeded the Food and Agriculture Organization permissible limits but the Botswana Bureau of Standards effluent limit was not exceeded. The mean nickel concentrations were below the threshold limits for both local and international standards. Statistical analysis showed no significant difference between the mean chromium and the mean nickel concentration in the leaves and the fruits of the tomatoes at the 5% significant level. It can be concluded from this study that cultivating tomatoes with sludge amended Glen Valley soil combined with normal treated waste water at pH 8.5 could reduce the uptake of chromium and nickel uptake in tomato plants. However, an increase in the uptake of chromium and nickel in the leaves and fruits of the tomato plants could be triggered at slightly low pH (pH 5.0 and pH 6.0) and high pH (pH 10.0) of the treated waste water. It is recommended that the current practices of using treated waste water combined with sludge amended Glen Valley soil to cultivate tomatoes at the Glen Valley farm is good practice and should be continued. Nonetheless, further studies need to be carried out at the farm to establish possible phytotoxicity effects of these heavy metals on tomatoes when using treated waste water combined with sludge amended and sludge absent soils. / Dissertation (MSc)--University of Pretoria, 2011. / Chemical Engineering / unrestricted