Cuticular Modifications in Colocasia esculenta (L.) Schott. and Xanthosoma maffafa (L.) Schott. Accessions Exposed to Some Oilfield Chemicals in the Niger Delta, Nigeria

Aim: To evaluate the effects of sodium thiosulphate and graphite powder on the epidermal characters of Colocasia esculenta and Xanthosoma maffafa accessions.

Study Design: The Randomized Complete Block Design was used for this study.

Place and Duration of Study: The Ecological Research Centre of the University of Port Harcourt, Nigeria between April 2015 and June 2016.

Methodology: A total of eight accessions were used for this study, five from Colocasia esculenta and three from Xanthosoma maffafa. Each accession was planted in a 10 kg soil and planted in 4 different concentrations (5, 10, 20 and 40 mg/kg) of sodium thiosulphate and graphite powder and the unpolluted soil was used as the control experiment. Epidermal sections were obtained using the hand teasing method.

Results: These test plant species were observed to be amphistomatous, and had five types of stomata: brachyparacytic, amphibrachyparachytic, brachyparatetracytic, brachyparahexacytic-monopolar and brachyparahexacytic-dipolar. The brachyparacytic type of stomata was observed to be the basic stomata type. Stomatal complex and contiguous stomata were observed on the abaxial epidermes of some accessions; while the control of NXs 003 was the only accession with contiguous stomata on the adaxial epidermis. The least stomatal index and stomatal frequency were observed in the adaxial epidermes of NCe 001 and NXs 002 while the highest stomatal index was observed in the abaxial epidermis of NCe 003 both treated with graphite powder. Accession NXs 003 had the lowest mean number of epidermal cells of all the accessions. The mean number of epidermal cells on both the adaxial and the abaxial epidermal surfaces were observed to be lowered by sodium thiosulphate treatments. The anticlinal walls were not affected by the treatments as the anticlinal walls were straight for both the control and treated accessions. Statistical analyses showed that the differences in stomatal indices and number of epidermal cells between the adaxial and abaxial epidermes were significant at 5% and these differences between accessions were also significant at 5%.

Conclusion: Different accessions of C. esculenta and X. maffafa showed sensitivity to environmental change and have unique way of adapting to ecological differences.