Influence of Semidwarfism and Genetic Background on Stand Establishment of Wheat1

Abstract

The objective of this study was to determine the influence of genetic backgrounds and semidwarf plant height genes (Rht1 and Rht2) on wheat (Triticum aestivum L.) stand establishment. Final stands (FS) and emergence rate indexes (ERI) were measured in 2 test years for eight populations, each including 15 isolines of two‐gene scmidwarf, one‐gene semidwarf, and normal heights. In 62 of 64 comparisons, the FS and ERI values of two‐gene semidwarfs were significantly lower than those of their one‐gene semidwarf or normal counterparts. One‐gone semidwarfs usually had lower FS and ERI values than their normal counterparts and these differences were significant for 23 of 32 comparisons.Two‐gene and one‐gene semidwarfs and normal isolines of the eight populations averaged 38.9, 51.9 and 61.0 seedlings per plot (FS), respectively; the average ERI values of these three height classes for all populations were 89.7, 161.2, and 228.2, respectively. However, highly significant differences for both FS and ERI occurred among the eight populations during both test years. Variations due to height classes, test years, populations, and their interactions were also significant.Results indicate that the Rht1 and Rht2 genes for semi‐dwarfism either reduce stand establishment capabilities or are genetically related to genes which do. The extent to which semldwarfism influences FS and ERI was appreciably altered by different genetic backgrounds. The backgrounds of the ‘Omar’ and ‘Golden’ cultivars minimized adverse effects of semidwarfism on FS and ERI, whereas the backgrounds of ‘Brevor,’ ‘Burt,’ ‘Itana,’ and ‘Marled’ cultivars had especially adverse or erratic effects on both stand establishment traits.