Nutrient use efficiency in crops and its genetic improvement

Genetic improvement of nutrient use efficiency has been a hotspot of plant nutrition research. However, there are still quite a few of misunderstanding on the concepts of nutrient efficiency and their physiological components, and nutrient efficient plant traits as well, which resulted in biased evaluation on the breeding efficiency for nutrient-efficient cultivars. The concepts and the meaning of nutrient use efficiencies and their components were discussed in detail. The general advances in the studies of nutrient genetic efficiencies of plants and the genetic breeding were introduced. From the point of views of crop science, plant nutrition, plant molecular biology and genetics, the physiological characteristics of efficient nutrient uptake and utilization were analyzed. In addition to the limitation of the field-level high-throughout phenotyping techniques, the lack of understanding of the physiological mechanism of efficient nutrient use at field level and the lack of a clear concept of the secondary indicator for genotype identification have been limiting the progress of breeding for nutrient efficiency. The molecular tools should be used to enhance the understanding of the physiological mechanism of nutrient use efficiency at field level. Genetic improvement on nutrient use efficiency should link nutrient uptake, allocation and reutilization with the regulation of plant growth and development. The optimum plant traits under population condition must be stressed and the selection should be conducted under true field conditions.