Responses of different arabica coffee (Coffea arabica L.) clones to varied environmental conditions

Different improved coffee arabica crosseshaving resistance to coffee berry diseaseand leaf rust, plus a standard cultivar,were grown under a range of environmentalconditions in a series of field trials inKenya. The effects of location and year ofproduction and their interactions with theclones were determined for berry yield.These data were used to estimate andcompare methods of analysis of GEI. An AMMImodel, joint regression model and ANOVAwith repeated measurements were used toinvestigate these interactions. The resultsindicated the relative effects of theclones and the environmental conditions,with Meru being the location where therewas greatest discrimination between theclones, probably because it was bettersuited for coffee. Clones,environments and joint regressions combinedaccounted for 31.20% of the interaction,leaving a residual of 68.80%. Significantresidual mean squares showed therelationship between clones andenvironments not to be strictly linear,thus indicating that regression analysisdid not always provide good estimates ofindividual clonal performance acrossenvironments. High correlations wereobtained between mean yield and regressioncoefficients and between ecovalence andmean square deviations as well as thecoefficient of determination. Resultsshowed that the improved clones surpassedthe standard cultivar both in terms ofyield and stability.Different analyses of the various aspectsof genotype response enabled the 21 clonesto be classified into different similaritygroups based on their performance andphenotypic stability as measured by variousstability parameters and the use of biplotsfrom the AMMI analysis.