Investigating the scope for managing the root system of spring barley crops to improve performance on drought-prone soils

Summary

Sector:
Cereals & Oilseeds
Project code:
PR316
Date:
01 April 2000 - 31 March 2003
Funders:
AHDB Cereals & Oilseeds.
AHDB sector cost:
£205,014 from HGCA (Project No 2264)
Project leader:
I J BINGHAM and V McCABE SAC, Crop and Soil Research Group, Craibstone Estate, Bucksburn, Aberdeen, AB21 9YA With contributions from M.J. FOULKES, University of Nottingham

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pr316-final-project-report

About this project

Abstract

Water availability can significantly limit cereal yields in the UK in some regions in some years. Predictions of climate change suggest that the frequency and severity of water-limitation is likely to increase over the coming years. It is important, therefore, to develop management strategies to improve crop performance at drought prone sites. One approach is to try and modify the root system so that it can access more water. The aims of this project were to investigate the potential for managing the root system of spring barley, through variety choice and the use of plant growth regulators. A particular objective was to provide the industry with targets for the scale of change needed to a cereal root system to access more water, and the possible yield benefits that might arise. The project involved a combination of controlled environment, glasshouse and field experiments.

A range of genotypes, including several modern UK semi-dwarf varieties, an older tall variety, and wild barley from the Middle East, were screened for differences in root characteristics under well-watered conditions. There was relatively little variation amongst the different genotypes. Chalice, a modern variety had the fastest growth rate and hence produced the largest root length and mass. There was no consistent difference between the semi-dwarf varieties and the tall variety. Four 'modern' varieties were selected for further study (Chalice, Optic, Chariot and Derkado). The varieties did not differ in their response to drought, or their ability to utilize water from wet soil zones deep in the soil profile, although they did differ in their accumulation of the plant stress hormone, abscisic acid. Optic accumulated very little in its roots compared to Chalice. This raises questions about the nature of its role in controlling shoot functions under drought. From the results, there appears to be little scope at present for matching varieties of spring barley to the drought risk of a site on the basis of their root traits. A specific breeding programme is likely to be needed to make significant genetic improvements to the root system.

The effects of an anti-gibberellin plant growth regulator (trinexapac-ethyl, Moddus®, Syngenta) and a biostimulant growth promoter (Route®, Loveland Industries) on root growth and the drought response of cv Optic were studied in detail in field and outdoor lysimeter (large drums of soil) experiments. In the field experiments, there was no effect of either treatment on yield at three contrasting sites. Detailed measurements of root growth at one site revealed no effect on root number, total root length and the length and mass at any soil depth. Drought in lysimeters reduced yield by 1 t per ha, but there was no effect of Moddus or Route on water extraction and drought tolerance of the crop. There is no evidence from these experiments, and little in the scientific literature, to show that growth regulators have a significant effect on root growth of cereals and water capture from the important deep soils layers.

Simple models have been developed to predict the effects of changes in root distribution on wheat yield on different soil types and under different seasonal weather patterns. The model provides the industry with targets to work towards for making genetic improvements to the root system. Some further development is needed to consider possible interactions between water and nutrient uptake.

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