Performance of cultivars, hybrids and composites of winter wheat (Triticum aestivum L. em Thell) grown at three locations

Graduation date: 1988The objective of this study was to compare three genetically\ud different groups of winter wheat for their grain yield. Experimental\ud material consisted of parental lines grown in pure stands, hybrids, and\ud 1:1 mixtures of the parental combinations. Three sites were employed to\ud evaluate possible interactions between the different groups across\ud locations. Phenotypic correlations among selected agronomic traits and\ud grain yield within each group along with the expression of heterosis\ud and heterobeltiosis in the hybrids were studied.\ud Results of this investigation support the general conclusion\ud reached by other investigators that hybrids and composites are not\ud consistently superior to the best conventional cultivars of wheat for\ud grain yield. However, at the Moro site, with the greater environmental\ud stresses, some hybrids and composites appeared to yield more than the\ud parental lines grown in pure stands. At Pendleton, the best environment\ud for yield expression, the hybrids and conventional cultivars did not\ud differ for grain yield. At this location, the best hybrids and one\ud composite did significantly outyield the commercial cultivars Stephens,\ud Malcolm and Hill, but not four advanced parental selections when grown\ud in pure stands.\ud Low to moderate values of heterosis and heterobeltiosis for grain\ud yield were found. The degree of expression being affected by the\ud specific growing site. Plant height and the number of kernels per spike\ud showed relatively higher values for heterosis and heterobeltiosis over\ud locations when compared to the other traits.\ud Phenotypic correlations suggested that a breeding program to\ud develop hybrid wheat should combine high number of kernels per spike\ud with high kernel weight. The positive correlation between grain yield\ud and plant height indicated that increases in grain yield could be\ud obtained by increasing plant height if lodging did not present a\ud problem