Abstract
To explore the potential use of GA-responsive dwarfing gene <i>Rht9</i> 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 <i>Rht9</i> dwarf lines derived from two crosses of Chinese winter wheat cultivars Xifeng 20 and Jinmai 47 with the <i>Rht9</i> tetraploid donor Granaoto. Xifeng20-<i>Rht9</i> dwarf lines reduced plant height on average by 25.38%, while on average by 9.39% in Jinmai47-<i>Rht9/Rht8</i> dwarf lines. Compared with taller parents, coleoptile length was reduced by 19.80% in Xifeng20-<i>Rht9</i> dwarf lines, while it was increased by 14.22% in Jinmai 47-<i>Rht9/Rht8</i> dwarf lines. There were no adverse effects of <i>Rht9</i> 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-<i>Rht9</i> 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-<i>Rht9/Rht8</i> dwarf lines. Compared with taller parents, <i>Rht9</i> 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 <i>Rht9</i> 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.
Highlights
Wheat is grown mostly in arid and semiarid regions, taking about one fifth of all crop acreage worldwide, and is the staple food for 40% of the world’s population [1]
Rht9 dwarf lines of Xifeng20 and Jinmai47 were identified by the Polymerase chain reaction (PCR) products using the linked SSR marker BARC151 for Rht9, while the presence of Rht8 in the dwarfing lines of Jinmai47 was confirmed using WMC503, which suggested that the Rht9 dwarfing lines of Jinmai47 was under the Rht8 background (Figure 1)
Investigation revealed that lengths of peduncle and all the internodes were significantly reduced in Rht9 dwarf lines of Xifeng 20 to significantly reduce overall plant height, while, only the second and third internode length from the spike were significantly reduced in Rht9 dwarf lines of Jinmai 47
Summary
Wheat is grown mostly in arid and semiarid regions, taking about one fifth of all crop acreage worldwide, and is the staple food for 40% of the world’s population [1]. Due to the increasing global population and limited arable land, wheat production and yield improvement become more and more important. The introduction of semi-dwarfing genes into rice (Oryza sativa) and wheat (Triticum aestivum) contributes prominent yield increases during the Green Revolution [2]. High yields were associated with improved lodging resistance and the ability to tolerate higher rates of inorganic nitrogen-based fertilizers [3]. The use of dwarfing genes to reduce plant height, increase harvest index, improve lodging resistance and increase grain yield has been one of the major strategies in developing modern bread wheat cultivars. Donor of dwarfing genes Rht-B1 and Rht-D1 from Japanese origin variety Norin 10 was first introduced to United State, to CIMMYT, where new semi-dwarf wheat varieties were developed by Norman Bourlag (1968) and
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