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 approach to grain yield improvement has been sought by using exotic germplasm to enhance quantitative traits, including grain yield. This study was conducted to determine whether synthetic hexaploids, developed from artificial hybridization of durum wheat [Triticum turgidum ssp. durum (Desf.) Husn.] with 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 evaluated 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 superior to their recurrent parent for kernel weight. Eight lines had significantly higher grain yield compared with their recurrent parent. Grain yields of superior lines were up to 11% higher than those of their recurrent parents. A strong association between grains m(-2), biomass, spikes m(-2), and grain and biomass production rates and grain yield was observed in all populations. 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 improve kernel weight.