Auxin (IAA), gibberellin (GA), phosphoenolpyruvate carboxylase (PEPC), ADP-glucosepyrophosphorylase (AGPase), phosphoribosyl pyrophosphate (PRPP), adenosine monophosphate synthetase (AMPSS) and phosphoribosyl pyrophosphate aminotransferase (PRPPAT) were extracted and assayed with a ELISA kit from Shanghai HengYuan Biological Technology Co. Ltd. (Shanghai, China). Soil available P content was extracted with 0.5 mol L 1 sodium bicarbonate solution, and the absorbance was measured by spectrophotometer afer molybdenum and antimony35. Phosphorus use efciency (PUE)=(P accumulation in P area - accumulation of P in blank area)/P application rate × 100%36.
