Abstract

Ekanem, A.M. and Osuji, J.O.*

Mitotic index studies were carried out on three cultivars of Xanthosoma and four cultivars of Colocasia. Young healthy roots (about 15 mm) were collected at 2 hourly intervals from 6:00 am to 8:00 pm. Root tips were fixed in 1:3 ethanol : acetic acid for 24 h and stored in 70% ethanol prior to squashing in FLP orcein. Microscopic counts showed that the dynamics of mitosis varied slightly between the two groups of cultivars. The peak of metaphase remained between 12:00 noon and 2:00 pm for most of cultivars but one (NCY 00Sa), which had its metaphase rising to a peak between 2:00 and 4:00 pm. This suggests that the best time to harvest root samples for optimum metaphase is immediately before 12:00 noon.