Punjab Agricultural University, Ludhiana 141 004.
1 Dedicated to Professor Dr. W. Gerhard Pollmer, Stuttgart, Germany, in honour of his excellence in maize breeding, and with gratitude for his guidance and help.
Identification of environments favouring selection of superior genotypes should help plant breeders reduce the costs of multi-environment evaluations. The objectives of this study were to develop indices which measure suitability of environments for conducting selection and to apply the indices to a multi-location experiment in maize (Zea mays L.). The indices were derived using the rationale that selection in a suitable environment should lead to a high response in the target environments. The value of a selection environment was found to be a product of linear regression coefficient of the observed performance of genotypes in the target environment on the performance in the selection environment and standard deviation of the performance in the selection environment. It was termed as an index of general response to selection (GR index) when based on the performance averaged over a number of target environments. The correlation (rts) between the average performance across target environments and that in a selection environment was shown to quantify the GR index and the ratio of response to indirect vs. direct selection. The 18 locations evaluated differed for GR index, rts and discriminability (DA; linear regression of the performance of genotypes in a selection environment on the average performance across all target environments); rts was closely correlated with GR index; and some locations possessed high GR index as well as DA with respect to maize grain yield. The study gave the indices that are useful in characterizing the suitability of environments for conducting selection and in choosing environments better than others for conducting selection for grain yield in maize.
Selection environment, response to selection, discriminability, maize, grain yield
