Yield and stability of groundnut ( Arachis hypogaea L.) varieties in the derived savanna areas of South-western Nigeria

Abstract

AaSTRACT Three improved and multiple disease-resistant groundnut lines (UGA 3. UGA 4 and UGA 13) and a local cultivar (Ogbomoso cultivar) were evaluated tor yield and stability on farmers' tields at Oyo, Ogbomoso and Shaki in the derived savanna areas of South-western Nigeria in 1997 and 1998. Pod yields ditler between the locations and ranged. from 0.54 to 0.74 t ha-1• The three improved varieties had similar yields ranging from 0.71 to (UG t ha-1 while Ogbomoso cv. had the lowest yield of 0.34 t ha-l Significant genotype x environment interaction intluence on pod yield was partitioned into ditlerent interaction principal component analysis (lPCA) axes by using additive main effects and multiplicative interaction model (AMMI). The first IPCA (IPCA 1) axis accounted significantly for the interaction. The biplot graph of mean yields and IPCA 1 scores showelil that UGA 3 with IPCA I score of -0.003 had a stable yield while other variety yields were unstable across the trial sites. The yield responses of the groundnut varieties to changes in environment were quantified by linear regression models: Y=0.40 0.09X" for Ogbomoso cv.; Y=0.61 + 0.30X·· tor UGA 13; Y=-0.81 + 2.44X·· for UGA 4, and Y=0.16 + 1.28X"· for UGA 3. The models indicated that a change in the environment had less impact on yields of Ogbomoso cv. and UGA 13 while an improved environment would increase the yield potential of UGA 4 and UGA 3 substantially. UGA 3 which was high yielding and stable across the ditferent sites will fit well into the' peasant farming system in South-western Nigeria.