Abstract
Optimizing wheat height to maximize yield has been an important aspect which is evident from a successful example of green revolution. Dwarfing genes (Rht) are known for yield gains due to lodging resistance and partitioning of assimilates into ear. The available and commercially exploited sources of dwarfism in Indian spring wheat are Rht1 and Rht2 genes inspite of availability of over 20 dwarfing genes. Rht8 a Gibberellic acid sensitive dwarfing gene is another reduced height gene commercially exploited in some Mediterranean countries. Two F2 populations segregating for Rht1 and Rht8 genes with each comprising 398 and 379 plants were developed by crossing European winter wheat cultivars Beauchamp and Capitole with Indian spring wheat cultivar PBW 621. Different genotypic combinations for Rht1 and Rht8 genes were selected from these populations through linked molecular markers and selected F3:4 lines were evaluated for various agronomic traits in a replicated trial. Reduction in plant height with Rht8 and Rht1 averaged 2.86% and 13.3% respectively as compared to the group of lines lacking dwarfing gene. Reduction was spread along all the internodes of wheat culm and reduction was lower as progress towards the lower internode. Grain number per spike and highest yield was observed in lines carrying only Rht1 gene. Reduction in plant biomass was observed with either of the dwarfing gene. Longest coleoptile length and seedling shoot length averaged 4.4 ± 0.09 cm and 19.5 ± 0.48, respectively was observed in lines lacking any of the dwarfing gene. Negligible reduction of 6.75% and 2.84% in coleoptile length and seedling shoot length, respectively was observed in lines carrying only Rht8 gene whereas F3:4 lines with Rht1 gene showed 21.64% and 23.35% reduction in coleoptile length and seedling shoot length, respectively. Additive effect of genes was observed as double dwarfs showed 43.31% and 43.34% reduction in coleoptile length and seedling shoot length.
Highlights
To meet the escalating demand of fast growing human population, there is need of continuous increase in wheat grain production
Molecular marker assay for Rht1 and Rht8
It has been concluded that Rht1 gene is responsible for semi-dwarfing nature of spring wheat line used (PBW 621)
Summary
To meet the escalating demand of fast growing human population, there is need of continuous increase in wheat grain production. The control of plant height in wheat is known to be complex because of its polygenic nature and environmental effects. Rht is mainly commercialized in Europe and transferred through Japanese variety Akakomugi from Japan to Italy and from Italy to other parts of Europe [5] These reduced height genes are effective in reducing plant height and have been widely adopted in wheat breeding programs since their introduction in the 1950s [6]. The aim of the study was to assess the potential of Rht gene in combination with Rht gene in elite spring wheat background under Indian environmental conditions
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