关键词: 小麦, 显性矮秆基因, 弱致矮力显性矮源, 近等基因系, 矮化育种

Abstract: Using near isogenic lines, 12 dominant and semi-dominant dwarfing genes were incorporated into 4 medium or tall statured wheat varieties (F1B4 recurrent paternal parents), thus establishing 4 sets of near isogenic lines of dwarfing genes. A two-factor comparative experiment with these near isogenic lines was conducted in non-competitive populations to study the effects of dwarfing genes and the genetic background of the recurrent paternal parents on the main agronomic characters of these near isogenic lines. The results showed that while reducing the plant height of the recurrent paternal parents, the dominant and semi-dominant dwarfing genes delayed their heading and slightly reduced their 1000-seed-weight. Dwarfing sources (genotypes) with a plant height of less than 50 cm are difficult to be directly used in plant breeding due to their low biomass production, and the utilization of the genetic background of medium or tall statured recurrent paternal parents had only limited results of enhancing the phenotypic plant height of the dwarfing varieties, the range of height increment being less than 10 cm. However, the present study has demonstrated again that dominant dwarfing genes, which are ultra-dwarfing, are liable to develop by mutation into a group of multiple alleles with plant height enhanced to different extents and some may have a height close to the ideal plant height for wheat breeding. As a major mutation occurs in the dominant dwarfing genes accompanied by enhanced plant height, the agronomic characters improved accordingly. Grain weight per plant increased by 0.19 g when plant height increased by 1 cm. When the plant height of a semi-dominant dwarfing variety increased to about 60 cm, its grain yield per plant may be similar to or event higher than the per-plant yield of the medium or tall statured recurrent paternal parents. Hence they can be directly used as innovative dwarfing sources in dwarfing breeding of wheat. Based on an evaluation of the genetic resources, we recommend that SW07, SW05, YD-Dwarf, SW02 and Rht21 selected in our experiment as innovative dwarfing sources be directly employed in wheat breeding. It is argued that strengthening the study and utilization of semi-dominant dwarfing sources will facilitate wheat gene design and dwarfing breeding in the post-green revolution era.