Restricted-tillering wheat does not lead to greater investment in roots and early nitrogen uptake

Jairo A Palta,Ian R.P Fillery,Greg J Rebetzke

doi:10.1016/j.fcr.2007.03.015

Jairo A Palta, Ian R.P Fillery + Show 1 more

https://doi.org/10.1016/j.fcr.2007.03.015

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Improving the ability of wheat root systems to capture soil nitrate (NO 3 −) before it moves below the rooting depth offers the potential to improve crop productivity in deep sandy soils. This dictates that roots grow fast, proliferate early and profusely. The root growth characteristics and the early nitrogen (N) uptake of double haploid lines from an intervarietal cross between restricted-tillering and vigorous wheat were investigated in two glasshouse experiments. In the first experiment double haploid lines B25 and A35 were compared with the cultivar Janz and the line Vigor 18, while in the second experiment the double haploid lines F20 and F25 were compared with the same two genotypes. In each experiment the genotypes were grown in glass-walled boxes. The restricted-tillering gene reduced the number of tillers produced in the double haploid lines, but this did not necessarily result in greater root biomass, root length and root number. Furthermore, root mass per unit of root length, total root biomass and root length were not related to the number of tillers produced. No differences in the root-to-total biomass among genotypes were found so there was no evidence that a surplus of photoassimilates was invested in enlarging, expanding or thickening the root system. F20, the least restricted-tillering double haploid line, had root biomass, root length and root number as high as the vigorous line Vigor 18. It also exhibited the characteristic early and more abundant root branching of Vigor 18. These below-ground parameters were strongly correlated with leaf area, shoot biomass and N uptake, suggesting that enlarging and expanding of the root system and hence improving N capture by roots might be under the control of vigor gene(s) rather than under the control of restricted-tillering gene(s). The implications of this control on improving the acquisition of N in deep sandy soils with high-leaching potential is discussed.

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