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Aims: For an effective potato breeding strategy, knowledge of the genetic parameters of traits, such as heritabilities and genetic correlations are essential, hence the need to assess the genetic variability estimates of yield-related traits in Irish potato mutants Study Design: At M1V1 generation, there was no replication of the mutant minitubers because each does not maintain the same genetical constitution after irradiation. In M1V2 and M1V3 generation the tubers were replicated 3 times in alpha lattice design. Place and Duration of Study:Irradiation was done at the Plant Genetics and Breeding Laboratories (PGBL) at IAEA/FAO Seibersdorf, Vienna, Austria. After mutation induction, the mutant microtubers (consisting of Asante, Mpya and Sherekea) were was transported to Kenya, University of Eldoret for establishment between April 2015 and March 2017. Methodology: A total of 30 tubers each of the three potatoes was sent for irradiation. Two in-vitro radio-sensitivity tests were developed involving different tissues: Irradiation of in vitro nodal cuttings Original Research Article(without leaf) followed by in vitro shoot propagation and irradiation of in vitro nodal cuttings (with leaf) followed by direct in vitro micro-tuber production. After mutation induction, a total of 570 mutant microtubers (Asante 230, Mpya 160, Sherekea 180) were developed from the three potato varieties and was transported to Kenya, University of Eldoret for the establishment. The M1V1 microtubers were established in the greenhouse while M1V2 and M1V3 generations of mutants were planted at the at the University of Eldoret research field. Results: It showed that the highest positive heritability percentage (H 2 ) estimates in Mpya and Sherekea mutants were in plant height with 81.51% and 87.7% respectively. Conclusion: Tuber number exhibited high heritability estimates displaying that induced mutation was successful in the development of new potato genotypes which be used in future breeding programs.

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Aims: Potato (Solanum tuberosum L.) is the most important staple food in the world and plays an important role in food and nutritional security. Induced mutation generates variation within potato germplasm to widen the genetic base for breeding purposes. Polyploidy modifies both the genotype and phenotype of an organism, generating diverse changes that consequently transform the potato production. Potato has chromosomes with different ploidy levels which can be determined by counting chloroplasts in stomatal guard cells. Study Design:  The study was carried out in completely randomized block design. Place and Duration of Study: Department of Biotechnology, University of Eldoret, between February 2015 and July 2016. Methodology: The study involved 163 potato mutants developed from three commercially grown Kenyan potato varieties; Asante, Mpya, and Sherekea irradiated using gamma rays from 60Co source under different dose rates. Three middle leaves of greenhouse-grown plants were randomly selected for chloroplast counts in ten pairs of stomata guard cells on the lower surface of the leaf. Data on the number of chloroplast counts per mutant was calculated as a percentage of the parents or control and descriptive analysis. Results: The results indicate that the number of ploidy level distribution was decreasing in diploids and triploids and were increasing in tetraploids from M1V1, M1V2 to M1V3 in all the potato mutant populations. Conclusion: This shows that mutation induction generates genetic variations from which desired mutants may be selected based on the appropriate breeding strategies.

The morphological traits of induced potato plants established from irradiated microtubers with Co60 gamma rays led to the identification of solid mutants with linear leaf shape and various chimerical mutants at the M1V1 stage. Potato breeding requires genetic variation of useful traits for crop improvement. The use of induced mutations is highly effective in enhancing genetic variability. The objectives of the study were to determine dose of mutagen and effects of induced mutation on morphological traits in potato. The study involved potato clones; Kenya Sherekea, Kenya Mpya and Asante (M1V0) improved varieties as parents. Populations of 300 potato mutants were developed by irradiation of microtubers with different dose rates (0, 3, 5, 6, 9, 10, 12, 15, 20 and 30 Gray (Gy)) of gamma rays of Co60 source at Seiberdorf laboratories in Vienna, Austria. The microtubers M1V0, M1V1, M1V2 and M1V3 were established at the University of Eldoret Greenhouse. Data collected on morphology observed was computed using SAS and means separated using Fisher’s protected LSD at 95% significant level. The morphological traits results showed that, there were significant difference in genotypes and dose of mutagen at p≤0.05 for most traits studied. Exposure to higher doses of gamma irradiation (20 and 30 Gy) had significant influence (p≤0.05) on the stem number, number and weight of tubers. This suggest that mutation induction generates genetic variations from which desired mutants may be selected based on the needs and preferences and further assist breeders in developing appropriate breeding strategies to decipher potato production constraints.