ABSTRACT

This study was carried out to ascertain the optimal growth medium for germination and seedling growth of botanic seeds of D. rotundata. Five growth media types were used. The experiment was laid in a completely randomized design with four replications. Results showed that Top Soil + Carbonized Sawdust medium (ratio 2:1) gave the highest germination percent (95%) and germination index (1.10) while Top Soil + Carbonized Rice husk medium (ratio 2:1) gave the highest seedling vigor index (1875.00). The maximum leaf number (3.68±0.46), leaf area (27.37 ± 5.63cm2), shoot.length (9.92 ± 1.33cm), root length (7.54 ± 1.45cm), seedling height (21.04 ± 2.24cm) and stem girth (0.55 ± 0.02 cm) of botanic seeds was observed in medium of Top Soil + Carbonized Rice husk. The highest shoot number was observed in Top Soil medium (2.18 ± 0.17). Carbonized Sawdust medium had the highest root number (8.40±0.93). Micro tuber weight was highest in Top Soil + Carbonized Sawdust medium (2.52 ± 2.51g). This study was also carried out to ascertain the nutritional, anti-nutritional and anatomical features of wild yam in comparison to the edible white yam using standard analytical methods. Extracts from leaves, stems, roots and tuber were used for this study. Results showed that proximate compositions of the tuber of the wild yam (D. praehensilis) had higher mean value in crude protein, crude fat, crude fibre, ash and moisture content except carbohydrate in comparison to the tuber of white yam. Average mineral elements (Ca, Fe, Mg, K and Zn but P) in the tuber were also found to be higher in the wild yam (D. praehensilis). Phytochemical compositions like phenols, oxalates and saponins except alkaloids, flavonoids and tannins were also found to be higher in the wild yam (D. praehensilis) in comparison to the tuber of white yam. The content of the oxalates in the wild yam (D. praehensilis) were not exceedingly higher (0.67 ± 0.05mg/bOg) compared to the white yam (0.45 ± 0.03mg/i 00g) but can be reduced to insignificant amount by boiling. Results from comparative morpho-anatomical features of wild yam (D. praehensilis) and white yam were almost the same in their midribs, stems and roots except their abaxial epidermal features, where epidermal cell wall of wild yam (D. praehensilis) was curvy while the white yam was sinuous. The wild yam (D. praehensilis) had higher stomatal index than the white yam. In conclusion, the study of the optimal medium for botanic seed germination and seedling growth showed that Top Soil + Carbonized Sawdust medium was the best in germination of the yam botanic seeds while Top Soil + Carbonized Rice husk was positive in the general performance of yam botanic seedling growth; The wild yam (D. praehensilis) was shown to be a good source of essential minerals and phytonutrients which possesses strong phérmacological activities and can be exploited in medicine for the treatment of ailments; and the anatomy provided evidences which may be combined with other existing lines of taxonomic evidences in arriving at a better identification and classification.