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University of Zululand (2010)

Genetic improvement of selected indigenous Cucurbitaceae species important for food and medicinal purposes in KwaZulu-Natal, South Africa

Ntuli, Nontuthuko Rosemary

Titre : Genetic improvement of selected indigenous Cucurbitaceae species important for food and medicinal purposes in KwaZulu-Natal, South Africa

Auteur : Ntuli, Nontuthuko Rosemary

Université de soutenance : University of Zululand

Grade : Master of Science (MS) in Botany 2010

Résumé
Coccinia palmata (Cogn.) and Lagenaha sphaerica (Sond.) Naud. are indigenous Cucurbitaceae species widely distributed in pantropical to tropical regions of Southern Africa. They are widely used for food and medicinal purposes, in nature these species exist as diploids, with their basic haploid (n) chromosome numbers being 12 and 11 for C. palmata and L sphaerica respectively. However, in higher plants nuclear DNA endoreduplication often occurs during their growth and differentiation which causes polysomaty in their tissues. For both C. palmata and L sphaerica, the optimum germination conditions were 25°C under light. Growth was either in the nursery (in pots/bags) or in the field (with and without bags). Colchicine treatment of seeds before and after incubation for germination was used to induce polyploidy in both of these Cucurbitaceae species. The effectiveness of colchicine in inducing polyploidy (genetic improvement) in the roots and shoots of both species was established. In both species treated roots had higher tetraploid and octoploid ratios than leaves. Colchicine treatment lowered the germinability (germination percentage), induced dwarfism, enhanced stem branching, reduced leaf area and number of stomata, and increased guard cell length and leaf chlorophyll content in both species. In C. palmata, colchicine treatment increased root fresh and dry weight but reduced shoot fresh and dry weight. However, colchicine treatment inhibited female plants’ flowering and therefore fruiting in both species.

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