AGRONOMIC VARIABILITY IN SELECTED TRITICUM-TURGIDUM X T-TAUSCHII SYNTHETIC HEXAPLOID WHEATS

Two trials were conducted at the Mexican National Institute of Agricul tural Research Experiment Station at Yaqui Valley, Sonora, Mexico to i nvestigate the nature and extent of agronomic variation in 50 syntheti c hexaploid (SH) wheats (2n = 6x = 42, AABBDD) derived from Triticum t urgidum (2n = 4x = 28. AABB) x T. tauschii (2n = 2x = 14, DD) crosses for subsequent use in wheat improvement. Plant height, spike length, d ays to flowering, physiological maturity, grain yield, above-ground bi omass at maturity, harvest index, yield components and test weight wer e determined. Significant agronomic variation was observed among the g ermplasm evaluated. Outstanding SH genotypes were identified with high er grain yield, above-ground biomass at maturity, 1000-grain weight, a nd spikes m-2 than the bread wheat (Triticum aestivum L.) check cultiv ar Seri 82. Genotypic correlations of grain yield with other character traits show that grain m2 was the most important determinant of grain yield (r = 0.993). Data on agronomic traits subjected to complete lin kage cluster analysis resulted in classifying the genotypes into two d istinct phenotypic groups excluding Seri 82. Groups generally correspo nded to durum progenitors of the SH with significant group differences for all characters. This demonstrates use of practical numerical anal ysis procedures to describe agronomic variation in representative SH g enotypes. Clustering by quantitative traits may be valuable for identi fication of genotypes with divergent sources for breeding and agronomi c purposes.