Genotype difference in the physiological characteristics of phosphorus acquisition by wheat seedlings in alkaline soils

Abstract

Phosphorus (P) in soils occurs predominately as insoluble inorganic P and organic P. However, key factors controlling P acquisition by wheat (Triticum aestivum L.) seedlings are unclear. In this study, the difference in the physiological characteristics of P acquisition in alkaline soils was investigated in wheat seedlings of two cultivars Aikang 58 and Zhoumai 22. The results indicated that the shoot P concentration of Aikang 58 was significantly higher than that of Zhoumai 22 when supplied with 0 and 70 kg/ha of pure P under field conditions. When cultured in sterile nutrition solutions with equimolar amounts of P corresponding to KH2PO4, Ca3(PO4)2, and Ca(H2PO4)2 for 6 days, the P concentration in the shoots and roots of the seedlings of Aikang 58 was significantly higher than that of Zhoumai 22. However, the P concentration of seedlings of Aikang 58 did not exhibit a significant difference than that of Zhoumai 22 when cultured in phytic acid solution. Further studies suggested that the proton secretion rate was higher, and the root phosphatase activity was significantly lower in Aikang 58 compared with those in Zhoumai 22. After 48 h of successive P starvation, the inorganic phosphate (Pi) uptake rate of Aikang 58 was significantly higher compared with that of Zhoumai 22. However, no significant differences existed in the root morphology between the two cultivars. Hence, the higher P acquisition in the wheat seedlings of Aikang 58 was attributed to a higher rate of proton secretion and a stronger capacity for Pi uptake.

Keywords

• p fertiliser
• p form
• calcareous soil
• utilisation efficiency
• p-efficient wheat cultivar