Acquisition or utilization, which is more critical for enhancing phosphorus efficiency in modern crops?

Phosphorus (P) is one of the major factors worldwide limiting crop growth. Enhancing P efficiency in plants can be achieved through improving P acquisition, utilization, or both. Which of these approaches is more critical for enhancing P efficiency in crops, particularly in intensive cropping systems? P availability is unevenly distributed through the soil profile. Most modern crop cultivars are selected through conventional breeding approaches for better adaptation to stratified soil P by root architectural and morphological traits that allow for more P acquisition from the P-rich soil surface zone. Conversely, most crops have relatively efficient P uptake capacity but low P translocation and remobilization. Hence, phosphorus utilization efficiency (PUE) becomes a significant bottleneck for further improvements in crop P efficiency. Furthermore, the modification of root systems requires additional carbon input, and thus crops might sacrifice carbohydrates for higher yield to meet demand for P acquisition. With the support from soybean transformation studies, we speculate that enhancement of PUE might become a potentially powerful strategy for increasing P efficiency in modern crops grown in intensive cropping systems. (C) 2010 Elsevier Ireland Ltd. All rights reserved.