Improving Nutrient Use Efficiency in Crops

Abstract

Optimum use of mineral nutrients (fertilisers) by crops is essential for sustainable agricultural production. With increasing world demands for food and energy, this is set to become an ever‐increasing priority. Fertilisers are costly to produce and apply, both financially and environmentally. There is an absolute requirement to maximise efficiency using both agronomic and plant breeding approaches. Nutrient use efficiency may be defined as yield per unit fertiliser input or in terms of recovery of fertiliser applied. Improving yield alone may be at the expense of mineral nutrient content and hence quality, therefore yield improvements must be matched by appropriate increases in nutrient uptake. Multiple complex processes contribute to the overall nutrient use efficiency trait, and all are multigenic and developmentally and environmentally modulated. Key breeding traits for improvement includes root characteristics to enhance acquisition, canopy functioning for yield generation, and sink tissue attributes for final yield and quality aspects. Multidisciplinary approaches involving traditional breeding and biotechnology will contribute to future improvements. Key Concepts: Optimum use of mineral fertilisers by crops is essential for sustainable agriculture. Some fertilisers are nonrenewal resources. Nutrient use efficiency may be defined as yield per unit fertiliser input or in terms of recovery of fertiliser applied. Nutrient use efficiency comprises two main traits, uptake efficiency and utilisation efficiency. Agronomic practice is an important part of nutrient use efficiency. Crop improvement may be targeted at roots, canopy or harvested material. Root systems and transporters are required for capture of nutrients to produce an effective canopy. An effective canopy will result in high yield. Efficient captures and partitioning of nutrients contributes to quality components of crops. Huge unexploited natural germplasm diversity for nutrient use efficiency exists for most crops.

The Genetics of Nitrogen Use Efficiency in Crop Plants

“…To some degree, breeders already target this strategy, given that average grain yields have increased steadily in the United States since the early 1980s without increased application rates of N fertilizer (59). Therefore, as has been noted by many researchers, if breeders select for improved yield at a constant N, by definition, NUE improves (61). Ideally, the N response curve of the future varieties will not only show N efficiency but will also be N responsive (62).…”

“…A simple example of improving NUpE would be to increase uptake with expression of more efficient transporters, or increase expression of all the transporters; however, it is unlikely that upregulating transporters only would increase N uptake (61). A second example is to target genes identified to play a part in root architecture (54,140).…”

“…The lateral roots, which occupy more than 90% of the total length of the root system, play a major role in water uptake. Despite their importance, it has proven difficult to perform field-based root phenotyping (61). To date, studies have been carried out to identify root morphological features www.annualreviews.org • The Genetics of Nitrogen 9.7 Changes may still occur before final publication online and in print such as root mass and depth, root axis length, and lateral branching related to NUE (69,110,136).…”

“…Therefore, NUE in terms of evolutionary fitness is very different from NUE in an agricultural setting. Historically, the Long Term Broadbalk experimental plots implemented in 1843 at Rothamsted in the United Kingdom have provided a wealth of data that have documented the long-term changes in crop NUE (61). These historical plots have demonstrated the importance of N-based fertilizers, the increase in yield gains from improved crop genetics, and the effect of increased N fertilization levels on N loss into the environment (61).…”

Improving Seed Potato Leaf Area Index, Stomatal Conductance and Chlorophyll Accumulation Efficiency through Irrigation Water, Nitrogen and Phosphorus Nutrient Management

“…Potato plants have a high demand on soil nutrients and their proper management is one of the most important factors required to obtain maximum tuber yield (Braun et al, 2015).Therefore, it is important to maintain high soil fertility through balanced nutrient supply (ICIPE, 2006). Optimum use of mineral fertilisers by crops is essential for sustainable agriculture and nutrient use efficiency comprises both uptake efficiency and utilisation efficiency (Hawkesford, 2012). The aim of fertiliser application is to feed the soil, which in return feeds the plant.…”