Abstract The wheat ( Triticum spp.) Reduced height‐1 ( Rht‐1 ) B1b and D1b semidwarfing alleles have been well studied since their incorporation into modern breeding populations in the 1960s. Useful alternatives to these alleles have been studied in hexaploid wheat ( Triticum aestivum L.), but less so in tetraploid durum wheat ( Triticum turgidum L. subsp. durum ). Most durum varieties are either tall or semidwarf, containing either the Rht‐B1a (tall) or Rht‐B1b (semidwarf) alleles. Because of the dosage‐dependent nature of these alleles, tetraploid semidwarf durum wheat is significantly shorter than hexaploid semidwarf wheat, meaning that in low resource environments, semidwarf durum varieties may yield less and are often too short to be effectively harvested. Thus, the identification of Rht‐1 alleles that confer intermediate height is needed. Near isogenic lines were created to test previously characterized alleles Rht‐B1b ‐E529K, Rht‐A1‐ S50F, and Rht‐A1‐ L358F in field trials to measure grain yield. The Rht‐B1b ‐E529K allele was additionally tested in greenhouse trials to evaluate emergence rates at different planting depths. Rht‐A1‐ S50F and Rht‐A1‐ L358F do slightly affect height but also may reduce yield. Rht‐B1b ‐E529K confers intermediate height, single grain weight, grain protein content, and seedling emergence when compared to lines containing the Rht‐B1a allele or the Rht‐B1b allele. Rht‐B1b ‐E529K also increased grain yield by 8.8% compared to Rht‐B1b in one of the five tested environments. The results show that the Rht‐B1b‐ E529K allele could be useful in regions where drastic decreases in height and reduction in seedling emergence conferred by Rht‐B1b can be detrimental.
Hale et al. (Thu,) studied this question.