Abstract

Polyploidy was induced in Corchorus olitorius L., a traditional leafy vegetable, which is also consumed by the rural community at KwaMbonambi. Corchorus seeds were treated with colchicine at four different concentrations (0.025, 0.05, 0.075 and 0.1 g/l) for 2, 4, 6, 8 and 10 h, respectively. For the control, treatment seeds were imbibed in water only. After germination in petri dishes, seedlings were transplanted to seedling trays and then to plastic pots and kept under shade cloth at the University of Zululand. There were three replicates for each treatment in a completely randomized design. Several morphological traits were measured and data were subjected to ANOVA, principal component analysis and cluster analysis. Significant (P<0.05) variation was observed among all traits measured, with all traits decreasing in value as the colchicine concentration and treatment duration increased, with the exception of stem girth. Of all traits measured, only the leaf chlorophyll content of plants treated with 0.025 g/l colchicine for two hours was significantly (P<0.05) higher than for the control treatment. The principal component analysis showed that the first two principal components (PC1 and PC2) contributed more than 80% of the total variation. The Pearson's correlation coefficients were positive and significant (P<0.05) for the majority of studied traits. Clustering pattern showed a close relationship between the C. olitorius plants treated with low colchicine concentrations and shorter treatment durations. A similar trend was also observed in the biplot. Colchicine treatment induced sufficient variability among treatments to be useful in future breeding programmes.