Abstract:

The objective of this study was to explore the physiological mechanisms of phosphorus absorption and utilization in the typical wheat cultivars with different phosphorus (P) efficiencies. The results indicated that the grain yields of the cultivars with high P absorption efficiency (Ha) and high P utilization efficiency (Hu) under the P-deficient condition were higher than that with low P efficiency (L) which was related to the more P accumulation and the higher P use efficiency, respectively (Fig.1). Under P-deficient condition, the secondary root number, the radius of secondary root and the root dry weight per unit soil were the highest in Ha, the middle in Hu, and the lowest in L (Fig.2). The root TTC reductive activity, the soluble protein content of root and the activity of secreted acid phosphatase (APase) from root at the jointing, spiking and mid-filling stages were also the highest in Ha, the middle in Hu, and the lowest in L (Fig.3–5). The APase activities in the spring fourth leaf and flag leaf were increased with the leaf grow under the sufficient or deficient conditions. Under the deficient condition, the APase activities measured in whole experiment were the highest in Hu (Fig.6). It was inferred that the increase of P absorption in Ha under deficient condition was due to the improvement in root architecture and the improvement of use efficiency of insoluble phosphate in the soil enhanced by secreting APase from roots. Meanwhile, the increase of P utilization efficiency in Hu under deficient condition was mainly caused by the higher APase activities in leaves by which the mobilized transfer and reuse of P in the plant were improved.

Key words: Wheat (Triticum aestivum), High P acquisition efficiency, High P utilization efficiency, Physiological mechanism