Natural variation in the efficiency of
nitrogen use by leafy vegetable crops
Ian Burns, Paul Hand*, James Durnford, Sandy McClement, James Lynn and Dave Pink*
* now based at Harper Adams University College, Newport, Shropshire
Natural variation in physiological and genetic constraints to nitrate uptake and assimilation
can be exploited by plant breeders to produce new N-efficient varieties of vegetable crops
that accumulate less nitrate and reduce the impact of N fertilisers on the environment
Frequency
distribution
grown in soil
grown hydroponically
Studies using a subset of a mapping population of approx 350 recombinant inbred lines of
lettuce (Lactuca sativa L) have shown a wide variability in nitrate content between lines
An average of 73% of this variability was caused by
differences in nitrate uptake by the roots and only
27% by differences in N assimilation in the shoots
Slope of line = 0.73
Lettuce lines with low nitrate contents accumulate more
soluble sugars and other solutes in their shoots to help
stabilise their osmotic potential and maintain the turgor
needed for leaf expansion and growth
Quantitative trait loci analysis is being used to identify the key
regions of chromosomes that control nitrate accumulation and
related processes
This will help plant breeders devise strategies for selecting
safer low-nitrate varieties of leafy crops which use N fertiliser
more efficiently and minimise losses of nitrate from soil to the
wider environment during their production
Acknowledgement: This work was funded by
Warwick Crop Centre
www.warwick.ac.uk/go/wcc