College of Natural and Applied Sciences

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Browsing College of Natural and Applied Sciences by Subject "2,4-D"

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    Degradation of 2,4-Dichlorophenoxyacetic Acid (2,4-D) by Ozonation and TiO2/UV Treatment
    (2007-04) Daidai, Masakazu; Kobayashi, Fumihisa; Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    The degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was conducted by ozonation, TiO2/UV treatment only, and two-stage treatment of ozonation followed by TiO2/UV treatment. In the case of ozonation, 2,4-D could be degraded and vanished within about 10 min at pH 9 and 20°C, but the TOC value was reduced by only about 40% by 30 min ozonation. In the case of TiO2/UV treatment, about 5 d was needed for complete disappearance of 2,4-D at pH 5 and 20°C. On the other hand, when the two-stage treatment of ozonation plus TiO2/UV treatment was applied, 90% decline of TOC was achieved within about 20 h, i.e., 30 min ozonation and 20 h TiO2/UV treatment thereafter. Furthermore, 90% of chloride ions in 2,4-D were liberated by the two-stage treatment. From a bioassay test of the two-stage treated water by the use of an osteoclasts of goldfish scales or Daphnia magna, it was found that 2,4-D was degraded into harmless substances with little estrogen activity and toxicity.
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    Evaluation of Regeneration Potentials of Farmerpreferred Cassava (Manihot Esculenta Crantz) Landraces to Unlock Cassava Transformation Barriers
    (2014) Elibariki, Gladness; Lupembe, M.; Hosea, Ken M.; Ndunguru, Joseph
    Evaluation of cassava germplasms for in vitro regeneration ability is crucial for stable genetic improvement of this crop via genetic transformation systems. Methods for reliable and efficient transformation including somatic embryo regeneration and recovery of transgenic plants still need to be developed and customized for each cassava genotype. Twenty one Tanzanian farmer- preferred cassava (Manihot esculenta Crantz) landraces widely grown in major cassava growing zones were evaluated for somatic embryo induction, recovery, sustainability and plantlets regeneration to whole plants. Somatic embryogenesis was induced from cassava leaf lobes on Murashige and Skoog media supplemented with different concentrations of sucrose, Copper sulphate and 2, 4-Dichlorophenoxyacetic acid and further developed to plantlets. Frequency of somatic embryo production and subsequently regeneration stages were evaluated starting from 28 days post-inoculation. All cassava genotypes tested in this study were able to induce callus where by 62 % were able to induce somatic embryo cotyledons. Cassava landraces: Sagalato, Rangimbili, Mnazi and Kibandameno were highly responsive to somatic embryo production. The conversion rate of embryos into plantlets was variable depending on the cassava landrace, Sagalato being the most responsive and Kiroba the least. Somatic embryos from 8 cassava landraces reached plantlet stage, 5 of them being acclimatized and successfully developed to plants with normal phenotype and they rooted on soil. The regeneration potentials of farmer-preferred cassava landraces observed in this study is hoped to pave a way towards genetic improvement for both biotic and abiotic stresses via genetic engineering approaches.