Abstract
Background and aimsWe were interested in the effect of impedance to root growth on root and shoot architecture of wheat. It is known that Rht-1 semi-dwarfing alleles decrease the degree of leaf stunting due to root impedance. We compared commercial wheat cultivars containing different Rht-1 alleles to determine whether leaf stunting caused by root impedance differed between cultivars. We investigated effects of impedance to root growth on the angular spread of roots.MethodsThe wheat cultivars Avalon, Robigus and Battalion, carrying semi-dwarfing alleles of Rht-1, and cv. Cadenza, carrying the tall, wild-type allele, were grown under two levels of soil strength in a sand culture system designed to allow the mechanical impedance of the root growth environment to be adjusted independently of water and nutrient availability.ResultsImpeded roots grew more steeply than non-impeded roots: the angular spread of roots decreased from 55° to 43° from the vertical, but the genotypic effects were weak. Root impedance reduced leaf elongation and the number of tillers. Leaf area and total root length provided a common relationship across all genotype x treatment combinations. Leaf stunting in Cadenza was more severe.ConclusionOur data support the hypothesis that the severity of leaf stunting due to root impedance is related to the Rht allele. Impeded roots had a smaller angular spread.
Highlights
To be productive wheat needs uninhibited shoot growth supported by a root system that is efficient at capturing available water and nutrients
Reduced GA signalling may be implicated in stunting leaf growth due to the root impedance, very little is known about the genotypic variability in leaf stunting in commercial wheat cultivars
There were no significant effects of the interaction between impedance and wheat cultivar on these data, the interpretation depends on the main effects
Summary
To be productive wheat needs uninhibited shoot growth supported by a root system that is efficient at capturing available water and nutrients. The stunting effect of root impedance on leaf elongation is well reported (Masle and Passioura 1987; Jin et al 2013) but very little is known about the extent of any genotypic variation. In the gibberellin-insensitive (GAinsensitive) severe dwarf NIL containing the Rht-b1c allele, leaf elongation was not reduced by root impedance, whereas leaf elongation in the tall Rht-B1a and semi dwarf Rht-B1blines was reduced. Reduced GA signalling may be implicated in stunting leaf growth due to the root impedance, very little is known about the genotypic variability in leaf stunting in commercial wheat cultivars. It is known that Rht-1 semi-dwarfing alleles decrease the degree of leaf stunting due to root impedance. We compared commercial wheat cultivars containing different Rht-1 alleles to determine whether leaf stunting caused by root impedance differed between cultivars. We investigated effects of impedance to root growth on the angular spread of roots
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