Plant behaviour insight could help arable farmers cut fertiliser use

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Some cereal crops can change their behaviour depending on whether a neighbouring plant is a friend or a foe – potentially helping farmers to cut fertiliser use and produce more stable harvests.

New research into how competition between barley plants affects enzyme activity could help producers achieve more profitable and consistent harvests because the study suggests that closely related crops work together – but work against rivals.

The research carried out between Manchester Metropolitan University and The James Hutton Institute, an interdisciplinary scientific research institute in Scotland, used two different cultivars, or varieties, of barley.

One cultivar was Scandinavian (named Tammi) and one Scottish (called Proctor), which has a slower growing time than Tammi due to the longer season and more temperate climate of its natural habitat.

Scientists looked at the rate at which the barley plants used carbohydrates released from roots to kick-start microbes to break down compounds in soil to produce nitrogen, which the plants then absorb as a form of nutrition.

It showed that plants delayed the release of these carbohydrates if a rival was near in a bid to stop the other plant ‘stealing’ the unlocked nitrogen.

Lead author Emily Schofield, a PhD student at Manchester Metropolitan University and The James Hutton Institute, said better understanding the timing and behaviours involved would help cereal crop breeders and arable farmers.

She said: “It’s to do with competition and survival, and recognising if a neighbouring plant is like you or not like you.

“When the plants were in competition the Scottish barley plant delayed its release of carbohydrates by seven days to limit microbial activity, keeping nutrients locked away in the soil.

“This may be a strategic approach to take up nutrients at the optimum time to maximise uptake by the plant and reduce the nutrients ‘stolen’ by a neighbour.

“The plants may therefore work with a closely related neighbour or to prevent the Scandinavian cultivar ‘stealing’ the nitrogen – and therefore a literal waste of energy – or both.

“Also, the Scottish barley roots seemed to grow downwards more quickly, a sort of escape response to the need to find new pockets of nitrogen.”

A barley seed is a fast grower: it can germinate in two days after sowing and sprout out of the ground in six.

Once harvested, if the grain contains the desirable right mix of nitrogen and carbon it can be sold by farmers to distilleries and breweries for use as malt.

But if the mix is wrong it can only be sold for animal feed at a much lower price.

Cereal crop growers will traditionally use two treatments of fertiliser on a barley field within the first two months of cultivation to support early growth.

Schofield said: “The amount and timing of fertiliser applied is crucial to the quality of the grain you get.

“If you’re growing a mixture of barley varieties in the same field then our research into the plant’s impact on microbial activity might help you plan better and use less fertiliser, saving you money, and producing higher quality and more stable crop, making the resulting harvest more profitable and sustainable.

“In cereal cropping there are big opportunities in the more efficient use of land using crop mixtures.

“Our research would be applicable to wheat cultivars or even inter-cropping, where you grow a cereal crop alongside peas or legumes.”

In the experiment, the researchers could track how the plants modified their microbial enzyme activity by observing on a sort of heat map the amount of activity of two classes of enzyme – leucine aminopeptidase and cellulose – present around the roots.

Measurements took place at 18, 25 and 33 days after planting.

Schofield said she found no evidence that the storing up of carbohydrate in the Proctor barley varieties caused by the delay had any adverse effect on the development of the plant itself.

The research was funded by the Scottish Government’s Rural and Environment Science and Analytical Services (RESAS) programme.

Schofield’s co-authors on the journal paper were Rob Brooker, Plant Ecologist, and Dr Eric Paterson, Root Physiologist/Biochemist, both from The James Hutton Institute; and Prof Liz Price, Head of Department of Natural Sciences; Dr Jennifer Rowntree, Senior Lecturer in Ecological Genetics and Applied Conservation, and Dr Francis Brearley, Senior Lecturer in Ecology, all at Manchester Metropolitan.

Link to the report https://www.sciencedirect.com/science/article/abs/pii/S0038071719302792?via%3Dihub

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