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Dr Malcolm Hawkesford, Dr Tony Miller, Dr Jonathan Howarth and Dr Darren Wells.
Rothamsted Research.

Techniques ancient and modern are being combined to tell us more about the best ways to grow crops to get maximum yield without overuse of fertilizer. The research mix includes smart plants that can signal the farmer when they need feeding, new devices that give direct readings of the amount of plant food available in the soil and a 160-year-old experiment that is still providing valuable data on crop management.

Since 1843, the Broadbalk field experiment has been used to compare plots of wheat grown with different food inputs such as inorganic fertilisers and farmyard manure. 'Originally worked by a team of oxen, this is the oldest continually running field experiment in the world', says Malcolm Hawkesford. 'The historical archive from Broadbalk includes crop yields, soil and plant samples and analytical data.'

Wheat samples from the various plots in the field experiment experience different levels of feeding both in terms of the mix of nutrients and the absolute level of food given to the plants. 'If a plant gets stressed because it is lacking a particular nutrient the way its genes are expressed will change', says Malcolm. 'By analysing the expression profiles of wheat genes from the various plots using microarray technology we can identify some marker genes in the plant that are switched on or off when a plant needs a particular food.'

'Finding out more about the genetics of crop plant nutrition is part of a drive to enable farmers to apply fertilizer with better precision, improving farm efficiency and decreasing the potential for pollution such as nitrate run-off, which is an increasing concern,' explains Malcolm. Nitrate run-off is a particular worry for those parts of the country recently declared as 'nitrate vulnerable zones'. Run-off occurs when there is a mismatch between the demand from the plant and the supply in the soil.

Rothamsted's exhibit will highlight one possible use of the marker gene technology: genetically modified 'sentinel plants' where one of the plants' 'feed-me' genes is linked to a reporter gene which might produce a green fluorescent protein. This would allow a farmer to inspect his growing crops with an ultraviolet or blue lamp and get an immediate indication of plant demand for nutrients and whether to add fertilizer or not.

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