A quantitative analysis of root distortion from contrasting wheat cropping systems
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The objective of this study was to analyse root distortion and root types in contrasting wheat cropping systems, and to determine their impact on yield.
Two field experiments with contrasting soils (structured vs poorly structured) were conducted using two tillage treatments (no-tillage, NT and conventional-tillage, CT), 4 straw mulch additions (0, 0.5, 2.5 and 5 t ha−1) and 3 N application rates (0, 25 and 100 kg ha−1). A novel methodology to describe root distortion was developed using vector geometry. Root length (RL), root distortion rate (RDR) and percentage of root types were the root parameters measured.
In structured soil, NT had lower RL (127 cm vs 184 cm), but higher RDR (36 ° cm−1 vs 26 ° cm−1) than CT, while the differences were not significant in unstructured soil. Heavy straw mulch reduced nodal roots (Nodal% 6.2 % vs 8.0 %) in both experiments. High N addition increased RL and RDR, but reduced Nodal% compared with low or no N application. RDR and Nodal% were positively correlated to grain weight, stem biomass, photosynthetic rate and stomatal conductance (r = 0.71 to 0.80).
Higher RDR in the NT system in structured soil or greater Nodal% in low/medium straw mulch in the unstructured soil positively affected photosynthesis and biomass production.
KeywordsWheat systems Root distortion No till Australia
This work was funded by the Australian Centre for International Agricultural Research project (CIM/2011/027). We thank Chris Penfold, Nigel Charman and Judith Rathjen at The University of Adelaide and Bill Davoren at CSIRO for help in establishment and maintenance of the field trials and collection of data.
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