Thesis (M.Sc. (Horticulture)) -- University of Limpopo, 2020 / Most rural communities harvest different plant parts of Jatropha zeyheri for nutritional and medicinal purposes. However, the decision of choosing to harvest the plant part with desired chemical components is essential for quality purposes. Nevertheless, there is a lack of information regarding the distribution of chemical composition in different plant parts of J. zeyheri tea. Therefore, the objectives of the study were to: (1) investigate the effect of different plant parts (stems, roots and leaves) of J. zeyheri on mineral composition and, (2) determine the effect of different plant parts (stems, roots and leaves) of J. zeyheri on phytochemicals and antioxidant activity. A study was conducted with three treatments, namely stems, roots and leaves arranged in a randomised complete block design (RCBD), with 10 replications. Plant materials were collected in the wild from mature plants between June-July 2018. Leaves and stems were manually separated, while roots were cut into smaller pieces, dried at 60°C for 48 hours in an air-forced oven and later finely ground using an electric grinder. Mineral elements were determined using Inductive Coupled Plasma Emission (ICPE-9000 Shimadzu, Japan). Phytochemical tests were performed to detect the presence of flavonoids, tannins, alkaloids and saponins, whereas 2,2-Diphenyl-1-picrylhydrazyl (DPPH) antioxidant qualitative test was performed using TLC plates. Antioxidant activity and phytochemicals constituents were quantified using UV/Visible spectrophotometer. Results of this study demonstrated that plant parts had a highly significant effect on essential mineral elements, copper (Cu), iron (Fe), potassium (K), magnesium (Mg), zinc (Zn), manganese (Mn), phosphorus (P) and nickel (Ni) contributing 82, 75, 97, 88, 86, 96, 79 and 82% to total treatment variation (TTV), respectively, whereas, calcium (Ca) had a significant effect contributing 69%, while no significant effect on sulphur (S) was observed. Among the tested essential mineral elements, Ca, Zn, Cu and Ni were consistently the highest in the leaf, followed by stem whereas, the root had the lowest contents. Manganese and Mg were consistently the highest in the stem, followed by leaf whereas, the root had the lowest content. Iron was highest in the leaf followed by root and was lowest in the stem. Also, the stem had the highest content of K whereas, the leaf and the root had moderately lower content, and P was high in the leaf, whereas, stem and root had lower content. Similarly, plant parts had a highly significant effect on non-essential mineral elements, aluminium (Al), sodium (Na), cobalt (Co) and chromium (Cr) contributing 85, 72, 84 and 81% in TTV, respectively, whereas, not significant on silicon (Si). Among the tested non-essential mineral elements, the leaf had the highest content of Al, Na, Cr, and Co followed by the stem, whereas, the root had the lowest. The screening of phytochemicals showed that flavonoids, tannins, alkaloids and saponins were present within different plant parts of J. zeyheri. The results from DPPH qualitative assay of J. zeyheri plant parts showed more yellow spots in leaf and root whereas, there was lesser amount in stem indicating that the plant exhibited antioxidant activity. Plant parts had highly significant effect on total flavonoids contributing 72% in TTV, however, had a significant effect on tannins and antioxidant activity contributing 56 and 79% in TTV, respectively. In contrast, plant parts were not significant on total phenols. The leaf had the lowest of total flavonoids content, whereas root and stem reported the higher contents and root had a lower content of tannins and antioxidant activity, whereas stem and leaf reported higher contents. In conclusion, the majority of chemical properties were recorded in leaves followed by stems and lastly in the roots. The result of this study suggested that J. zeyheri tea beverage can be brewed from leaves predominantly followed by stems or alternatively they can be combined. / National Research Foundation (NRF) and Limpopo Agro-Food Technology Station (LATS)

Agricultural businesses face many internal and external factors that significantly affect their business. Aspects such as management, marketing, internal and external environments are increasingly important for agricultural businesses in the Czech Republic. This thesis analyses the external environment of the company, including PEST analysis and Porter's five forces model. Both models are explored in detail including explanations of their main role and functionality within the given environment. Also explained is the Boston matrix to define the internal environment of the company. This thesis provides a SWOT analysis- techniques focused on the evaluation of internal and external factors influencing the organization's success. The practical part of this thesis will implement the theoretical aspects previously explored within a selected agricultural business of Central Bohemia. This thesis will explain and analyse the external and internal environment of the selected agriculture business. A general overview of the models will be defined and then implemented upon the agricultural business of Klučenice a.s.

Intercropping is an important cultural practice commonly used in pest management. It is based on the principle that the reduction of insect pest populations in the crop may occur due to the increase of agro-ecosystem diversity. The study was carried out aiming to assess the impact of colored fiber cotton-cowpea intercropping on both Aphis gossypii Glover, 1877 and Aphis craccivora Koch, 1854 (Hemiptera: Aphididae) aphid populations and their predators, especially Cycloneda sanguinea (Linnaeus, 1763) (Coleoptera: Coccinellidae). The study also aimed to evaluate the biomass production and the dispersion behavior of the aphids and their predators in this context. Experiments were carried out in laboratory, greenhouse and field conditions. Amino acids were extracted from cotton and cowpea plants. Under greenhouse conditions two wingless aphid species (A. gossypii and A. craccivora) and one predator species (C. sanguinea) were used to evaluate the dispersion, crop preference as well as predator progeny establishment. The influence of abiotic factors (temperature and relative humidity) in aphid dynamics was also analyzed. In field conditions the occurrence of arthropods found in sole or cotton and cowpea intercropped was evaluated. Mathematical models were developed to evaluate the aphid dynamics over time and statistical models were used to compare productivity in plants, dispersion, progeny and reproductive success of predator. Computational simulations were performed to compare the insect occurrence and to evaluate the best cropping system to pest reduction, natural enemy increase and plant productivity. Amino acid asparagine (ASP) was the most detected in the samples. Positive correlations were found between aphids and temperature. Negative correlations were found between aphids and relative humidity. Mathematical models described the dynamics behavior of aphids in arrangements studied. In all cropping systems an asymptotic growth was observed, with population peak and decrease in aphid population. Under greenhouse conditions, the sole cropping exhibited higher number of aphids than intercropping systems. The natural enemy dispersion was similar in both cropping system. However, the progeny abundance and cotton productivity were higher in treatment t1 (intercropping designed with cotton plants : cowpea plants in a row, started and ended with cotton plants). Simulations based in field experiments and literature showed that some cropping arrangements provided temporal dynamics stable in arthropods. However, Toxomerus watsoni (Curran, 1930) (Diptera: Syrphidae) exhibited temporal dynamics unstable and less abundance in arrangements of sole organic cotton or cotton-cowpea intercropping t1 that received insecticide for sucking pest control. Computational simulations confirmed that biomass production was higher in some cotton-cowpea intercropped than in sole cropping systems. / Consórcios são importantes práticas culturais comumente utilizadas no manejo de pragas. Baseiam-se no princípio de que a redução de populações de insetos-praga nos cultivos pode ocorrer devido ao aumento na diversidade do agroecossistema. O estudo foi conduzido objetivando avaliar o impacto que o consórcio entre algodão com fibra colorida e o caupi pode causar nas populações dos pulgões Aphis gossypii Glover, 1877, Aphis craccivora Koch, 1854 (Hemiptera: Aphididae) e seus predadores, especialmente Cycloneda sanguinea (Linnaeus, 1763) (Coleoptera: Coccinellidae). Objetivou-se também avaliar a produção de biomassa e comportamentos de dispersão dos pulgões e seus inimigos naturais nos cultivos. Experimentos foram conduzidos em condições laboratoriais, casa de vegetação e campo. Realizaram-se extrações de aminoácidos oriundos de plantas de algodão e feijão. Em casa de vegetação, ápteros de duas espécies de pulgões (A. gossypii e A. craccivora) e um predador (C. sanguinea) foram utilizados para avaliar a dispersão, preferência pelo hospedeiro bem como o estabelecimento da progênie do predador. A influência de fatores abióticos (temperatura e umidade relativa) na dinâmica dos pulgões também foi analisada. Em condições de campo, avaliou-se a ocorrência de artrópodes encontrados no algodoeiro e caupi solteiros e consorciados. Modelos matemáticos foram desenvolvidos para avaliar a dinâmica de pulgões ao longo do tempo e modelos estatísticos foram utilizados para comparar produtividade em plantas, dispersão, progênie e sucesso reprodutivo do predador. Simulações computacionais foram utilizadas para comparar a ocorrência de insetos e avaliar o melhor sistema de consórcio que reduza a população de pragas, aumentando a população de inimigos naturais e produtividade do cultivo. O aminoácido asparagina (ASP) foi predominante na maioria das amostras. Correlações positivas foram encontradas entre pulgões e temperatura. Correlações negativas foram encontradas entre pulgões e umidade relativa. Modelos matemáticos descreveram o comportamento dinâmico dos pulgões nos arranjos estudados. Em todos os esquemas de cultivos foi observado um crescimento assintótico, com picos populacionais e decréscimos na população dos pulgões. Em casa de vegetação, os cultivos solteiros propiciaram números de pulgões maiores do que os arranjos de cultivos consorciados. A dispersão do inimigo natural foi similar nos sistemas de cultivos solteiros e consorciados. Entretanto, a abundancia de sua progênie e produtividade de algodão foi maior no tratamento t1 (Consórcio delineado com plantas de algodão : plantas de feijão, cada linha iniciou e terminou com plantas de algodão). Simulações baseadas nos experimentos em condições de campo e literatura demonstram que alguns sistemas de cultivos propiciaram dinâmica temporal estável nos artrópodes estudados. Porém, Toxomerus watsoni (Curran, 1930) (Diptera: Syrphidae) apresentou dinâmica temporal instável e menor abundância nos arranjos de algodão solteiro orgânico ou no consórcio de algodão e feijão t1, que recebeu inseticida para controle das pragas sugadoras. Simulações computacionais confirmaram que a produção de biomassa foi maior em alguns consórcios de algodão com caupi do que em cultivos solteiros.