Effects of Gibberellic Acid Responsive Dwarfing Gene <i>Rht9</i> on Plant Height and Agronomic Traits in Common Wheat

To explore the potential use of GA-responsive dwarfing gene Rht9 in common wheat breeding program, its effects on plant height, seedling vigor, photosynthesis and yield traits were investigated and compared in field experiments using hexaploid Rht9 dwarf lines derived from two crosses of Chinese winter wheat cultivars Xifeng 20 and Jinmai 47 with the Rht9 tetraploid donor Granaoto. Xifeng20-Rht9 dwarf lines reduced plant height on average by 25.38%, while on average by 9.39% in Jinmai47-Rht9/Rht8 dwarf lines. Compared with taller parents, coleoptile length was reduced by 19.80% in Xifeng20-Rht9 dwarf lines, while it was increased by 14.22% in Jinmai 47-Rht9/Rht8 dwarf lines. There were no adverse effects of Rht9 on root characters and flag leaf characters, though slightly increased relative leaf chlorophyll content (SPAD) observed. Grain numbers per spike was increased on average by 19.63%, and biomass per plant was slightly decreased on average by 3.37% in Xifeng 20-Rht9 dwarf lines, while, grain number per spike was decreased on average by 11.49%, and biomass per plant was increased on average by 8.57% in Jinmai47-Rht9/Rht8 dwarf lines. Compared with taller parents, Rht9 increased fertile tillers on average by 11.25% and 11.19%, grain yield on average by 10.11% and 14.10%, harvest index on average by 12.67% and 6.85%, while decreased spike length on average by 4.80% and 16.23%, slightly decreased 1000 kernels weight by 4.43% and 4.61%, in the Rht9 dwarf lines of Xifeng 20 and Jinmai 47, respectively. The results of current study could be useful for proper use of dwarfing gene Rht9 to improve lodging resistance, grain yield potential in wheat breeding programs for water limited area.