Root growth in field-grown winter wheat: Some effects of soil conditions, season and genotype.

L Hodgkinson,R W Ashton,I C Dodd,R P White,W R Whalley,A Binley,C W Watts

doi:10.1016/j.eja.2017.09.014

Abstract

This work compared root length distributions of different winter wheat genotypes with soil physical measurements, in attempting to explain the relationship between root length density and soil depth. Field experiments were set up to compare the growth of various wheat lines, including near isogenic lines (Rht-B1a Tall NIL and Rht-B1c Dwarf NIL) and wheat lines grown commercially (cv. Battalion, Hystar Hybrid, Istabraq, and Robigus). Experiments occurred in two successive years under rain fed conditions. Soil water content, temperature and penetrometer resistance profiles were measured, and soil cores taken to estimate vertical profiles of pore distribution, and root number with the core-break method and by root washing. Root length distributions differed substantially between years. Wetter soil in 2014/2015 was associated with shallower roots. Although there was no genotypic effect in 2014/2015, in 2013/2014 the dwarf wheat had the most roots at depth. In the shallower layers, some wheat lines, especially Battalion, seemed better at penetrating non-structured soil. The increase in penetrometer resistance with depth was a putative explanation for the rapid decrease in root length density with depth. Differences between the two years in root profiles were greater than those due to genotype, suggesting that comparisons of different genotypic effects need to take account of different soil conditions and seasonal differences. We also demonstrate that high yields are not necessarily linked to resource acquisition, which did not seem to be limiting in the low yielding dwarf NIL.

Highlights

Wheat (Triticum aestivum L.) is a nutritionally and economically important crop grown in countries all around the world
The soil penetrometer resistance profiles before any water uptake were similar for each year (Fig. 1) and both show that even in the absence of any soil drying penetrometer resistance increases with depth
When the soil cores were taken from the field to estimate root distribution and the wheat was at heading stage, root length density decreased rapidly with depth (Figs. 6 and 7)

Summary

Introduction

Wheat (Triticum aestivum L.) is a nutritionally and economically important crop grown in countries all around the world. Within wheats that are currently grown commercially in the UK, there is recent evidence that some lines are more effective at accessing deep water than others, differences in water uptake at depth were not sufficiently large or consistent to identify extreme performers with any certainty (Ober et al, 2014). This may be partly due the impact of management on rooting depth. The field sites (i.e. soil type) had the greatest effect on the distribution of roots with depth, with one of the sites encouraging a much greater root length density at depths shallower than approximately 1 m in all of the wheat lines

Results

Discussion

Conclusion