Roots at heart of barley research

Barley varieties with more effective rooting, improved water uptake and more efficient nutrient use were being singled out in research being carried out by the James Hutton Institute.

Rooting performance of a number of spring barley varieties was being tested under varying degrees of soil compaction, said Alison Karley, a research scientist for the James Hutton Institute. “Our aim is to exploit varietal differences in rooting to improve water and nutrient use efficiency.”

Initial trials growing barley varieties in tubes showed significant differences in nitrogen uptake under different conditions, she said. “With relatively small changes in soil compaction we could see that nutrient uptake and water use efficiency was reduced.”

The tests were being rolled out to a wider range of varieties and she hoped the system could single out those with the most efficient rooting systems. This information could then be passed on to breeders, she noted.

In a sister trial, root mass had been measured under differing compaction levels and showed significant differences between varieties. The trials mimicked soil conditions found in 59 Scottish fields, half of which were inhibiting root growth through a combination of factors such as compaction and water availability, said research scientist Tracy Valentine.

“Varieties responded differently to this physical stress. Root length was reduced by varying amounts and placement of these roots in the soil was affected.”

This could also have a significant affect on nutrient uptake, particularly where there were low levels, she said.

Once rooting differences were detected in the lab, the trials would be extended into the field, she added. “We are also hoping to extend this to other cereal crops, particularly wheat.”

In another rooting trial, the layer of soil which sticks on the root surface was also found to have an effect on crop durability. Known as the rhizosheath, the soil layer retained moisture and nutrients close to the root, which was particularly valuable in stressed conditions, said research scientist Tim George. “Essentially the rhizosheath is the ability of the root to form a strong bond with the soil and it is largely to do with the root hairs.”

Speaking to Farmers Weekly after the event he said varieties producing larger rhizosheaths tended to produce more plant biomass. But if they became too large they drained the crops’ resources. “There will be an optimum size which improves water and nutrient capture without other costs being too high.”

A number of glasshouse trials had already been conducted and it was hoped field trials would be carried out next year, he said. “Ultimately, we want to use markers to identify genetic controls for the optimum rhizosheath and transfer this knowledge to breeders.”

This information should be available at the end of the project in four years’ time, he noted.

Effect of nitrogen steress

Initial trials results suggest some winter barley varieties perform significantly better than others when subjected to nitrogen stress, said Luke Ramsay, a research scientist for the James Hutton Institute.

Growth, yield and grain quality were being studied under three nitrogen regimes ranging from 65kg/ha to 225kg/ha and early results indicated genotypes responded differently, he said. “But generally root systems are larger with no applied nitrogen and smaller with higher rates. This indicates greater exploration under nitrogen limiting conditions.”

The study hoped to identify lines which maintained performance at reduced nitrogen rates and identify the genes responsible, he said.