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The effect of impedance to root growth on plant architecture in wheat
Kemo Jin1, Jianbo Shen2, Rhys W Ashton3
1Department of Plant Nutrition, College of Resource and Environmental Sciences, China Agricultural University, Beijing, 100193 China ; Rothamsted Research, West Common, Harpenden St Albans, AL5 2JQ UK.
Background And Aims:
We 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.
Methods:
The 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.
Results:
Impeded 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.
Conclusion:
Our 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.
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