Use of Triticum tauschii to improve yield of wheat in low-yielding environments

Triticum tauschii (Coss.) Schmal. is an ancestor of bread wheat (T aestivum). This species has been widely used as a source of simply-inherited traits, but there are few reports of yield increases due to introgression of genes from this species. Selections from F-2-derived lines of backcross derivatives of synthetic hexaploid wheats (T turgidum / T tauschii) were evaluated for grain yield in diverse environments in southern Australia. Re-selections were made in the F-6, generation and evaluated for grain yield, yield components including grain weight, and , Grain growth characters in diverse environments in southern Australia and north-western Mexico. Re-selection was effective in identifying lines which were higher yielding than the recurrent parent, except in full-irrigation environments. Grain yields of the selected derivatives were highest relative to the recurrent parent in the lowest-yielding environments, which experienced terminal moisture deficit and heat stress during grain filling. The yield advantage of the derivatives in these environments was not due to a change in anthesis date or grain-filling duration, but was manifest as increased rates of grain-filling and larger grains, indicating that T tauschii has outstanding potential for improving wheat for low-yielding, drought-stressed environments.