New insights into how plants regulate their absorption of an essential nutrient could help avoid pollution caused by excess use of fertiliser, according to researchers from the University of Edinburgh.

According to the researchers, the findings could lead to the development of crop varieties that need less of the primary nutrient – nitrogen – than crops currently being grown. It could also inform how much nitrogen should be added to plant feed. This, they claim, would allow improved plant growth, while limiting nitrogen run-off from fields, which is a major source of water pollution.

Agricultural fertilisers typically contain high levels of nitrogen that boost plant growth and yield even on poor soils. This helps plants avoid the typical characteristics of nitrogen deficiency - stunted growth and pale or yellow leaves.

Working with colleagues in Brazil, the Edinburgh team examined how nitrogen is absorbed and converted into cellular building blocks in plants.

They found that when nitrogen is absorbed, plant cells produce nitric oxide, which acts as a signalling molecule. This nitric oxide fine-tunes how much nitrogen is used for growth, by signalling to the plant's cells when to limit its uptake.

The scientists said that because nitric oxide plays important roles in shaping the development of plants, and how plants respond to environmental stress, these insights highlight key considerations of how nitrogen-based fertilisers should be used in agriculture.

Dr Steven Spoel of the University of Edinburgh's School of Biological Sciences led the study. Dr Spoel explained, "Understanding nitrogen absorption better will ultimately allow us to breed crop varieties that need less fertiliser, and therefore are better for the environment."