Abstract

M. M. Pretorius, J. Allemann and M.F. Smith

Upland cotton (Gossypiumhirsutum L.) is considered to be the most important textile fiber crop in the world. Unpredictable weather patterns caused a need for the identification of stable genotypes that have specific adaptation to specific environments. The objective of this study was to evaluate yield performance of different cotton cultivars under irrigation in South Africa by using the AMMI model. Five genotypes were evaluated over three seasons (2003 to 2006) at six locations. The additive main effects and multiplicative interaction (AMMI) statistical model was used to investigate the cultivar x environment interaction (GEI), yield stability and adaptation to environments. AMMI analysis indicated that cotton yield showed highly significant differences (p<0.01) affected by Environments (E), genotypes (G) and genotype x environment interaction (GEI). 84.0 % of the total sum of squares was attributed to environmental fluctuations showing that the environments were diverse, with large differences among environmental means accounting for most of the variation in cotton yield. Results showed that NuOPAL was the best performing cultivar in 15 out of 18 observations in fibre yields.