Agronomic potential of synthetic hexaploid wheat-derived populations

Wild relatives of wheat (Triticum aestivum L.) have primarily been used as sources of genes for biotic and abiotic stress resistance. A more direct ap proach to grain yield improvement has been sought by using exotic germplasm to enhance quantitative traits, including grain yield. This study was cond ucted to determine whether synthetic hexaploids, developed from artificial hybridization of durum wheat [Triticum turgidum ssp. durum (Desf.) Husn.] w ith Aegilops tauschii Coss., can enhance yield or yield components of wheat . Two hundred eighty-two BC2F2-derived lines, involving six crosses between different synthetic hexaploids and four spring wheat cultivars, were evalu ated for grain yield and its components. These synthetic-derived lines were compared with their recurrent parent in field experiments conducted during the 1995 to 1996 and 1996 to 1997 crop seasons near Ciudad Obregon, Sonora , Mexico. More than 80% of the synthetic-derived lines were significantly s uperior to their recurrent parent for kernel weight. Eight lines had signif icantly higher grain yield compared with their recurrent parent. Grain yiel ds of superior lines were up to 11% higher than those of their recurrent pa rents. A strong association between grains m(-2), biomass, spikes m(-2), an d grain and biomass production rates and grain yield was observed in all po pulations. Path coefficient analyses of yield components revealed a strong direct effect of spikes m(-2) and grains spike(-1) on grain yield. Results indicate that synthetic hexaploids can be a valuable source of alleles to i mprove kernel weight.