Improving crop nitrogen use in dryland farming: interactions and potential trade-offs between water- and nutrient-use efficiency

Abstract

Improved nitrogen-use efficiency and water-use efficiency (WUE) of dryland farming crops are important goals for cereal breeders. There have been considerable efforts to improve these traits separately, but now there is an increasing demand for crops with improvement in both of these traits. Analysis of ecological and crop-based experimental data has identified an apparent trade-off between N-use efficiency and WUE, suggesting that the two breeding goals are not compatible. This review summarises the physiology underlying these two traits and the genetic/breeding efforts underway to improve them. It then examines the observed interaction between N-use efficiency and WUE. Understanding the nature of this interaction provides scope to maximise yields in water-limiting environments whilst minimising N losses. Strategies focussing on genetic improvement to improve both traits concurrently are then discussed.