A quantitative analysis of root distortion from contrasting wheat cropping systems

Abstract

Aims: 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. Methods: 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. Results: 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). Conclusions: 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.