Variation and interrelationships of agronomic traits in Ethiopian tetraploid wheat landraces

Sixty tetraploid wheat (Triticum turgidum L.) landrace agrotypes collected from the central highlands of Ethiopia and one commercial check cultivar (Boohai) were evaluated at Akaki experimental station for grain yield and 11 other component traits. The objectives were to estimate phenotypic (PCV) and genetic (GCV) coefficients of variation, broad-sense heritability (H) and genetic advance (GA), and to determine the interrelationships among the various traits. Genotypic differences among the agrotypes were highly significant for all the traits considered. Compared to Boohai, the landrace agrotypes were later in days-to-heading (DTH) and maturity (DTM), and had shorter grain filling period (GFP), lower fertility (KS) and lower 1000-kernel weight (TKW). By contrast, they were superior to Boohai in tiller number (TN), biological yield (BY) and grain yield plant-1 (GYP). Intermediate to high order estimate combinations of GCV, H and GA (as % of the mean) were observed for TN, GYP, number of kernels spike-1 (NKS), harvest index (HI) and TKW. GYP showed a moderate heritability which was higher than GFP, BY and Plant height (PHt). DTH and DTM were strongly correlated, but both were negatively associated with the rest of the traits except PHt. The negative correlation of DTM with GYP was largely indirect via other characters. PHt had either a weak or negative association with the other traits. TN and TKW were positively correlated with GYP, and had high and intermediate direct effects, respectively. These two traits, however, were negatively correlated and showed a substantial counter-balance effect via one another. It appears that, for the short-term, improvement of the Ethiopian wheat landraces may be possible through indirect selection for TN and TKW or direct selection for grain yield per se. In the long-run, crossing programmes between indigenous and introduced germplasm may be necessary.