Payebo C.O, Ogburia M. N and Adeleke M.T.V
Ex-situ cytogenetic studies had been used for the determination of male fertility of clones of cultivated crops for conventional breeding and consequent production of ideotypes. The experiment consisting of seven (7) cassava cultivars in which pollen grains were excised from all the cultivars at anthesis, each treatment was replicated six (6) times and a total of two hundred (200) pollen grains were counted per cultivar. Treatments (pollen grains) were subjected to cytogenetic male fertility screening which was conducted in the Microbiology laboratory, Rivers State University. The treatments collected were arranged in Complete Randomization Design (CRD). Some baseline cytogenetic data were taken from all the cultivars such as number of stained pollen grains per cultivar, number of unstained pollen grains per cultivar, number of N-pollen grains per cultivar and number of giant pollen grains per cultivar. The Number of stained pollen grains were highest in Tms98/0505 followed by Tms96/1632 with the means 26.50 and 26.1 respectively while the least was obtained from 016/137. The highest number of unstained pollen grains were observed in cultivar 016/137 followed by 01/1368 with mean 14.83 and 14.33 respectively while the least were obtained from cultivar Tms98/0505 followed by Tms96/1632 with the mean 6.83 and 7.17 respectively. The highest number of N and giant/2N pollen grains were obtained from cultivar Tms419 Tms07/0593 respectively. Stainability/fertility percentages were calculated in which Tms98/0505 had the highest (79.5%) which showed significant difference (P>0.05) from the other cultivars except Tms96/1632 and the least was 55.5% obtained from 016/137 cultivar. The ex-situ findings of this research revealed that all the different species are fertile though their inherent fertility level/percentage varies from specie to specie as paternal parents and therefore, should be used for cassava breeding programs due to their inherent fertility as male parents especially Tms98/0505 and Tms96/1632.
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