Abstract:
Potato (Solanum tuberosum L.) is one of the tuber crops produced in Ethiopia, mainly at mid and highlands of Ethiopia, due to the absence of potato varieties adaptable to lowland areas of the country. The country has large arable land in lowland areas, Thus, developing varieties adaptable to these areas is important. this research was conducted to estimate the effect of genotype x environment interaction (GEI) on morpho-agronomic traits and determine yield stability of potato genotypes across locations and seasons in mid and lowland areas of Ethiopia. Nine potato genotypes were evaluated at three locations namely at Raree research station of Haramaya University, Melkassa and Dire Dawa) during 2021 main cropping season (rainfed production) and 2022 post rainy season (irrigation production). The experiment was laid in a randomized complete block design with three replications. The analysis of variance (ANOVA) for each location and season as well as over six environments (three locations over two seasons) showed the presence of significant differences among the genotypes for tuber yield, tuber quality, and yield related traits except the genotype had nonsignificant difference for percentage tubers of medium size. The interaction of genotype by environment (G x E) and interaction of genotype by season (G x S) had significant effect on all traits except G x E had nonsignificant effect on average stem number, proportion of tubers with very small, small and large sizes, and tubers dry matter content. Genotype, location and year interacted to influence phenology and growth traits, average tuber number/plant, total, marketable and unmarketable tuber yields. The results indicated the genotypes had differential mean yields over locations and years. The ANOVA results from Additive Main Effects and Multiplicative Interaction (AMMI) model showed that genotype, environment and genotype x environment interaction had 39.8, 25 and 16.5% contribution to the total variation of marketable tuber yield, respectively. The first (IPCA1) and second ((IPCA2) Interaction Principal Component Axis accounted 72.98% to sum squares of GEI in which IPCA1had a higher contribution of 46.03% to marketable tuber yield. The three genotypes, CIP392781.1,C IP397036.7 and CIP304371.67 had significantly higher marketable tuber yield of 26.38, 22.62 and 20.71 t ha-1 , respectively, than other genotypes over six environments. Moreover, CIP397036.7, CIP392781.1 and CIP304387.39 gave 20.88, 19.81 and 18.8 t ha-1 marketable tuber yield, respectively, at Dire Dawa indicated the genotypes were better adapted to the lowland area of eastern Ethiopia. Most of the stability parameters from AMMI, Eberhart and Russell’s models identified CIP392781.1, CIP397036.7 and CIP304371.67 as relatively stable genotypes for marketable tuber yield over six environments. Therefore, the genotypes for high marketable tuber yield and stable over environments as well as genotypes produced high yield at lowland could be further evaluated.