Multivariate Analyses to Display Interactions between Environment and General or Specific Combining Ability in Hybrid Crops

Abstract

Estimates of general combining ability (GCA) and specific combining ability (SCA) help plant breeders devise breeding and selection strategies. The objective of this paper was to apply two‐mode principal component analysis (PCA) to environment‐centered and normalized female (F) or male (M) × environment (E) tables and three‐mode PCA on F × M × E tables to display the variability associated with GCA, SCA, and their interactions with environments. A sunflower (Helianthus annuus L.) North Carolina Design II (4 females × 4 males) was grown in 11 environments in Argentina. Site regression (SREG2) and additive main effects and multiplicative interaction (AMMI2) models identified lines with high GCA and SCA. The two‐ and three‐mode PCAs revealed GCA × E and SCA × E interactions and were able to identify the best tester for either broad or specific adaptation. Two combinations of analyses accounted for all sources of variation. In Strategy 1 (explaining 59% of the genotype (G) + G × E interaction), two‐mode PCA displayed GCA + SCA while three‐mode PCA displayed GCA × E + SCA × E interactions. Strategy 2 (77%) used two‐mode PCA to display GCA + GCA × E interaction and three‐mode PCA to display SCA + SCA × E interaction. Both strategies were suitable approaches to understand the combining ability of the core germplasm of a hybrid crop breeding program and allowed decisions to be made about the required focus on line development within sub‐regions encompassed by the program.