EVALUATION OF EFFECT OF INDUCED MUTAGENESIS ON MORPHOLOGICAL AND AGRONOMIC TRAITS OF SELECTED IRISH POTATO ((Solanum tuberosum L.) VARIETIES IN KENYA.

Abstract

Potato is ranked fourth most important food crop in the world while in Kenya, it‟s the second most important food crop after maize. Although Potato has the widest genetic diversity among related wild species than any other cultivated plant, the germplasm cannot all be directly used for breeding due to a combination of ploidy level and endosperm balance number (EBN) incompatibility. Induced mutation, vegetative micro propagation and genetic engineering are a viable alternative method of improvement. The study was aimed in testing effect of induced mutagenesis on morphological and agronomical traits of Kenyan varieties of Irish potato (Solanum tuberosum L). Three Potato varieties: Kenya Mpya, Asante and Sherehekea were tested for induced soma-clonal mutation after irradiation dosages of 0, 3, 6, 10 and 12 Gy. The five levels of mutation dosages were evaluated to determine the suitable dosage level using augmented design. The LSD means separation by dosage at 5% level results indicated that the genetic variability occurred in all the mutagenic treatments and morphological traits under study showed wide range of genetic variability. All dosage levels were significant at P≤0.05, P≤0.01, and P≤0.001 for both qualitative and quantitative traits at all environments. Principal component analysis (PCA) allowed reduction of four traits into two variables (principal components), with weight of tubers contributing most in the first PCA and plant height contributing most at second PCA. Principal component analysis of the traits evaluated at both sites (Eldoret and Mau-Narok) showed similarity with weight of tubers contributing most in the first PCA and flowering period contributing most in the second PCA. The traits that form the first and second principal components show the strongest discriminatory power, which diversifies the studied accessions. Plot of first two PCoA axes from the sites separated accessions into clusters showing maximum and minimum similarities in comparison to controls. Selected varieties M81, S34 and A101 demonstrated quality traits in terms of increased yield and late blight resistance. Morphological descriptors after correlation analysis, showed positive correlation among the potato accessions in relation to parental traits magnifying genetic divergence among the accessions.