Magnitude of G x E interaction on root yield of 25 orange and white-fleshed sweetpotato varieties in Kenya

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Heritier Mbusa
James Muthomi
Florence M'mogi Olubayo
Ngugi Eliud Kahiu
Benjamin Kivuva
Felister Mbute Nzuve


Sweetpotato genotypes vary widely in root yield, beta-carotene and root dry matter content across different agro-ecological environments. This study aimed to determine the magnitude of genotype-environment interaction (GxE) on the root yield of twenty five improved and landrace sweetpotato genotypes across two sites (Kabete and Kiboko) during two different seasons (long and short rains). Sites combined by season given four different environmental conditions. Plots of four rows for each genotype at a planting density of 90cm x 30cm were planted under a Randomized Complete Block Design (RCBD) with three replicion. Each plot was made of sixteen plant per genotype. Data were collected on fresh root yield. An Additive Main Effects and Multiplicative Interaction (AMMI) was performed using GENSTAT software (15th edition) to determine the GxE effects. Fresh root yield of the sweet potato genotypes tested ranged from 17.63 to 54.79 tha-1. There were significant (P< 0.05) genotype and site effects for fresh root yield Genotypes Ininda, Erica, Jane and Tanzania consistently produced the highest fresh root yield across sites. In addition, the findings indicated that fresh root yield mostly influenced by environmental factors (P<0.05). Genotypes, Tanzania, Cecilia and Ejumula were the most stable varieties for root yield.
Keywords: Agro-ecological, AMMI analysis, AMMI stability value, genotype

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