Thesis (MSc. (Horticulture)) -- University of Limpopo, 2018 / Rainwater harvesting is an old age practice used in water-scarce rainfed crop production areas. It is practiced to supplement additional water for crops with insufficient amounts of rainfall for optimum production. The aim of this study was to assess yield responses of Swiss chard under In-field rainwater harvesting techniques (IRWH) and catchment areas. The trials were conducted at two sites, University of Limpopo experimental farm (Syferkuil) and on farmer’s field at Apel. The main plots were two catchment areas (2 m (1 m runoff strip plus 1 m basin)) and (3 m (2 m runoff strip plus 1 m basin)), while the subplots were five IRWH techniques namely; Control (farmers practice), Rainfed, IRHW (without mulch + irrigation), IRWH+Mulch and IRWH+Mulch+Irrigation. The results obtained showed no significant differences in yield of Swiss chard in relation to catchment areas of 3 and 2 m respectively. However, significant differences in plant height, plant vigour, number of leaves and chlorophyll contents were obtained under different IRWH techniques. Significantly, highest average plant height of 40.75 cm was obtained in IRWH+Mulch compared to Rainfed with the lowest average 28.50 cm at Syferkuil. A similar trend was obtained at Apel. There were significant differences in number of leaves under IRWH techniques; the highest mean of 16.00 was obtained in the control (farmers practice) treatment, while the lowest mean of 9.00 was obtained in IRWH treatment at Apel. At Syferkuil, significantly highest average number of leaves was obtained in the IRWH+Mulch+irrigation treatment, while the lowest average number of leaves was obtained in the rainfed treatment. Regarding the yield of Swiss chard, the significantly highest average yield was obtained under IRWH+Mulch+irrigation and 3 m catchment treatment combination which was 84.86 t ha-1 compared to 20.66 t ha-1 in rainfed and 3 m catchment treatment combination at Syferkuil. Similar trend was found at Apel with the highest average yield recorded in IRWH+Mulch+irrigation treatment combination. Hence, IRWH technique with mulch and irrigation could be adopted by growers in a water-scarce environment like the Limpopo Province of South Africa.

Land application of biosolid or industrial compost raises concerns regarding heavy metal accumulation in soils, plants and free-ranging livestock. A strip-split plot design evaluated two levels of sewage sludge (22/44 t ha-1) and municipal solid waste (21/42 t ha-1) compared to nitrogen fertilizer and an unfertilized control. Treatments were evaluated with three levels of limestone (CaCO3 at 0, 3 and 6 t ha-1) over two years corn seeded no-till. Swiss Chard cultivated in field soil samples within a greenhouse monitored heavy metal bioavailability. Compost amended soil was incorporated into chicken feed to simulate soil ingestion in a free-range production system. Compost application increased total soil Pb over time yet decreased both available soil and corn plant Cu levels over time. No heavy metal accumulation was observed in Swiss Chard or poultry tissue. Biosolid composts containing elevated Cu or Pb levels can be safely used for crop or free-range broiler production.

Thesis (M.Sc. (Agriculture, Plant Protection)) -- University of Limpopo, 2020 / The unavailability of environment-friendly nematicides for managing root-knot (Meloidogyne species) nematodes in crop husbandry have led to various alternative methods being sort which includes the development of cucurbitacin-containing phytonematicides. The cited phytonematicides consistently suppressed nematode numbers on different crops under greenhouse, microplot and field conditions, although there is lack of information on how the products would affect susceptible Swiss chard infected by root-knot nematodes. Swiss chard is one of most nutritious vegetables, grown throughout the year and is well adapted to different soil types. However, these products have the potential to induce phytotoxicity on various crops, if applied improperly. Phytotoxicity of phytonematicides on different crops, has been resolved by deriving Mean Concentration Stimulation Point (MCSP). The MCSP, developed using the Curve-fitting Allelochemical Response Data (CARD) computer-based model, is crop-specific, hence it should be developed for every crop. The objectives of this study were to investigate (1) whether population densities of Meloidogyne species, growth and accumulation of selected nutrient elements in Swiss chard would respond to increasing concentration of Nemarioc-AL and Nemafric-BL phytonematicides under greenhouse and microplot conditions and (2) whether the nemarioc-group and nemafric-group phytonematicides in liquid and granular formulations would affect population densities of Meloidogyne species and the productivity of Swiss chard with related accumulation of nutrient elements in leaf tissues under field conditions. Parallel experiments for Nemarioc-AL and Nemafric-BL phytonematicides were conducted concurrently under greenhouse and microplot conditions. Greenhouse experiment was prepared by arranging 25-cm-diameter plasticpods on greenhouse benches, whereas microplot experiment was prepared by digging holes and inserting 30-cm-diameter plastic pots in the field. The four-week-old Swiss chard seedlings were transplanted into the pots, filled with steam-pasteurised loam, sand and Hygromix-T at 3:1:1 (v/v) ratio. Treatments comprised 0, 2, 4, 8, 16, 32 and 64% phytonematicides arranged in randomised complete block design (RCBD), with six replications. Treatments were applied seven days after inoculation, with 3000 eggs and J2 of M. incognita race 4 under greenhouse conditions, whereas under microplot conditions were inoculated with 6000 eggs and J2 of M. javanica. Under field conditions, treatments comprised untreated control (0), 2 g Nemarioc-AG and 3% Nemarioc-AL phytonematicides (nemarioc-group) or 0, 2 g Nemafric-BG and 3% Nemafric-BL phytonematicides (nemafric-group), arranged in RCBD, each experiment with 8 replications. At 56 days after initiation of treatments, eggs in roots, J2 in roots and Pf exhibited negative quadratic relations under both greenhouse and microplot conditions. Under greenhouse conditions, dry shoot mass (R2 = 0.81), dry root mass (R2 = 0.87) and leaf number (R2 = 0.91) over Nemarioc-AL phytonematicide exhibited positive quadratic relations. In contrast, dry shoot mass (R2 = 0.78), dry root mass (R2 = 0.93) and leaf number (R2 = 0.70) over Nemafric-BL phytonematicide exhibited positive quadratic relations. Under microplot conditions, dry shoot mass (R2 = 0.95) and gall rating (R2 = 0.96) over Nemarioc-AL phytonematicide, exhibited positive quadratic relations. Dry shoot mass (R2 = 0.84) and gall rating (R2 = 0.97) versus Nemafric-BL phytonematicide exhibited positive quadratic relations. Selected nutrient elements under greenhouse conditions K (R2 = 0.96), Ca (R2 = 0.79), Mg (R2 = 0.64), Fe (R2 = 0.78) and Zn (R2 = 0.77) over Nemarioc-AL phytonematicide exhibited positive quadratic relations. In contrast, only Ca (R2 = 0.90), Mg (R2 = 0.68) and Zn (R2 = 0.84) over Nemafric-BL phytonematicide exhibited positive quadratic relations, whereas K (R2 = 0.72) and Fe (R2 = 0.63) over the product exhibited negative quadratic relations. Under microplot conditions, K (R2 = 0.82), Ca (R2 = 0.90) and Mg (R2 = 0.98) over Nemarioc-AL phytonematicide exhibited positive quadratic relations, whereas Fe (R2 = 0.91) and Zn (R2 = 0.79) over the product exhibited negative quadratic relations. In contrast, K (R2 = 0.60), Ca (R2 = 0.68) and Zn (R2 = 0.95) over Nemafric-BL phytonematicide exhibited positive quadratic relation, whereas Mg and Fe over the product did not have significant relationships. Under greenhouse conditions, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides on Swiss chard were 3.03 and 2.36%, whereas overall sensitivity (∑k) values of the crop to the product were 3 and 0 units, respectively. In contrast, MCSP values of Nemarioc-AL and Nemafric-BL phytonematicides on Swiss chard under microplot conditions was successfully established at 3.71 and 3.33%, whereas the ∑k values were 2 and 1 units, respectively. Under field conditions, at 64 days after initiating the treatments, the nemarioc-group phytonematicides had highly significant effects on eggs in roots and reproductive potential (RP), contributing 79 and 77% in total treatment variation (TTV) of the respective variables. In contrast, the nemafric-group phytonematicides had highly significant effects on eggs in roots and RP, contributing 67 and 76% in TTV of the respective variables. Under field conditions, all plant growth variables were not significantly affected by the treatments. The nemarioc-group phytonematicides had significant effects on K and Mg in leaf tissues of Swiss chard, contributing nemafric-group phytonematicides had significant effects on Mg, contributing 62% in TTV of the variable. In conclusion, the products could be used on Swiss chard for managing population densities of Meloidogyne species. However, due to the sensitivity of Swiss chard to the products, it would be necessary to use the derived MCSP values to determine the application intervals of the products on the test cultigen / National Research Foundation (NRF) Agricultural Research Council (ARC)

The meat industry is always alert to consumer s requirements. Consumer s are now in search for healthier products, once they are changing their food habits. The sodium nitrite and other chemical preservatives are related to diseases such as cancer and, because of that, food products without the use of cure agents, or naturally cured, are being largely studied. From vegetable extracts and a nitrate reducing starter culture can prepare cured meat products similar to the conventionally cured. The objective of this research was to develop and evaluate the quality of Italian salami produced by natural curing, using celery and Swiss chard extracts as nitrate source, with or without a nitrate reducing starter culture. Six treatments were evaluated (T1 0,8% celery extract and pre-incubated starter culture; T2 0,8% celery extract and no incubated starter culture; T3 1,2% celery extract and pre-incubated starter culture; T4 0,3% celery extract; T5 0,3% celery extract and pre-incubated starter culture; T6 0,3% Swiss chard and pre-incubated starter culture) and a control (sodium nitrate and sodium eritorbate). Physical-chemical analysis (pH, proximate composition, water activity, sodium nitrite and nitrate, color and TBARS (thiobarbituric test)), microbiological analysis (coliforms at 45ºC, Staphylococcus coagulase-positive, Salmonella sp., sulfite-reducing Clostridium and lactic acid bacteria) and sensory evaluation were done during the maturation period at 0, 1, 4, 7, 10, 15 and 32 days. During the storage period, the oxidative activity (TBARS) and the color of the salami, at 30, 60 and 90 days were evaluated. All treatments showed a development of the typical color of cured meat products and the physical-chemical and microbiological results corresponded to the Brazilian official food regulations. In the sensorial analyses, all treatments were considered worst than control, although treatments T4, T5 and T6 were considered acceptable. The attribute considered most different by the testers was the flavor followed by the odor. During the storage period, the color of the treatments was considered similar to the control, but evaluating the a* values, no color stability was observed in the treatments that used lower extract concentrations, and these values were higher in the treatments than the ones used in the pre-incubated starter culture. Meanwhile, for the color development the pre-incubation time was not necessary. At the end of the storage period, the control showed the highest TBARS value, demonstrating that the vegetable extracts used had an anti-oxidation effect. / A indústria cárnea está sempre atenta às exigências dos consumidores, e na busca por produtos saudáveis, uma vez que consumidores estão mudando seus hábitos alimentares. O nitrito de sódio é usualmente utilizado como conservante químico e está relacionado com doenças como o câncer, por isso, produtos elaborados sem a adição desse agente de cura, ou naturalmente curados, estão tendo uma ampla atenção. A partir de extratos vegetais e uma cultura starter nitrato-redutora, podem-se obter produtos cárneos similares aos curados convencionalmente. O objetivo deste trabalho foi desenvolver e avaliar a qualidade de salames tipo Italiano produzidos por cura natural, utilizando extratos de aipo e acelga como fontes de nitrato, adicionados ou não de culturas starters nitrato-redutoras. Avaliaram-se seis tratamentos (T1 - 0,8% de extrato de aipo e cultura starter pré-incubada; T2 - 0,8% de extrato de aipo sem incubação da cultura starter; T3 - 1,2% de extrato de aipo e cultura starter pré-incubada; T4 - 0,3% de extrato de aipo; T5 - 0,3% de extrato de aipo e cultura starter pré-incubada e T6 - 0,3% de extrato de acelga e cultura starter pré-incubada) e um controle (nitrato de sódio e eritorbato de sódio). Realizaram-se análises físico-químicas (pH, composição centesimal, atividade de água, nitrito e nitrato de sódio, cor e TBA (teste do ácido tiobarbitúrico), análises microbiológicas (coliformes a 45ºC, Staphylococcus coagulase positiva, Salmonella sp., clostrídios sulfito-redutores e bactérias lácticas) e análise sensorial. Após 30, 60 e 90 dias de armazenamento, foram avaliadas a estabilidade à oxidação lipídica (TBA) e os parâmetros de cor dos salames. Todos os tratamentos apresentaram desenvolvimento de cor típica de produto curado e os resultados físico-químicos e microbiológicos atenderam aos padrões da Legislação Brasileira. Sensorialmente todos os tratamentos foram considerados inferiores ao controle, porém, aceitáveis para os tratamentos T4, T5 e T6. O atributo mais prejudicado foi o sabor, seguido do odor. Durante o período de armazenamento, a cor dos tratamentos manteve-se de maneira semelhante à do controle, porém, avaliando os valores de a*, não apresentou estabilidade nos tratamentos com as menores concentrações de extratos, e estes valores foram superiores nos tratamentos onde houve pré-incubação da cultura starter. Entretanto, para a formação da mesma, não é necessário o tempo de pré-incubação da cultura starter. No final do armazenamento, o tratamento controle apresentou maiores valores de TBA, mostrando a eficiência dos extratos vegetais como antioxidantes.

Le travail est axé sur l'accumulation d'éléments chimiques essentiels et non essentiels avec une attention particulière pour les parties des consommées, en lien avec la qualité sanitaire des produits alimentaires. Le travail de thèse est divisé en deux grandes parties. La première porte sur une expérimentation en plein champ où des plantes de blettes et de tomates ont été cultivées du stade plantules jusqu'à la maturité pendant 5 mois avec des pratiques agricoles conventionnelles ou biologiques. Les plantes ont été récoltées à 6 stades différents de croissance et nous avons déterminé la concentration des organes végétaux pour 27 éléments chimiques. L'objectif était d'étudier la répartition des éléments entre les organes en fonction de l'âge de la plante et des pratiques culturales.La seconde partie de la thèse a été consacrée à la compréhension et à la modélisation de la répartition du cadmium (Cd) chez le tournesol aux stades reproducteurs. Des plantes ont été cultivées du stade plantule jusqu'à la maturité, en solution nutritive avec une faible concentration en Cd cohérente avec les expositions aux champs. Durant la phase reproductive, cinq échantillonnages ont été effectués pour comprendre la répartition du Cd entre les organes ainsi que l'origine du Cd des graines (prélèvement racinaire versus remobilisation à partir d'autres organes). Au stade du bouton floral et pendant le remplissage des graines, le devenir du Cd récemment absorbé par les racines a été suivi et modélisé par traçage isotopique avec du 111Cd. Les rôles de la transpiration et de l'allométrie entre organes ont été plus particulièrement examinés. / This work is focuded on the accumulation of essential and non-essential elements, paying a special attention to the dible part of the plants, in terms of food safety and human health. The thesis work has been divided in two main parts. The first one is related to a field expeiment performed in open-air plots, where Swiss chards and tomato plants were grown from seedlings to maturity in a natural soil during five months, using organic or conventional agricultural practices. Plants were harvested at six different growth satges and the total concentrations of 27 elements were measured in all plants organs. The objective was to study the partitioning of elements between the plant organs, depending on the plant age on the cultivation practice. The second part of the thesis is devoted to the understanding and modelling of the partitioning of cadmium (Cd) in sunflowers at the reproductive stages. Sunflowers wre grown in nutrient solution at low Cd availability consistent with thaht found in the field, from germination toi maturity. During the reproductive period, five samplings were carried out to investigate the partitioning of the total Cd between plant organs and the origin of the Cd allocated to seeds (root uptake vs; remobilization from other plant organs). At the flower bud and grain filling stages, the partitioning of the Cd recently taken up between the different plant organs was followed and modelled by exposing several plants for the three days to a 111Cd enriched nutrient solution. The roles of the transpiration and of the plant allometry were specially investigated.