Abstract: To probe into the adaptive mechanism of apple to phosphorus deficiency, a systematic study was made, with Malus hupehensis(Pamp) Rehd adopted as materials and by means of water-culture approach, about the dynamic changes of uptake of phosphorus by roots and root architecture parameters of M. hupehensis R. under the condition of P-deficiency and re-supplied P. Our results revealed that the greatest rate of absorption (I_max) of M. hupehensis R. young seedling in P-deficiency nutrient solution was constantly higher than that of M. hupehensis R. young seedling in full Hoagland solution, and tends to be relatively stable in 120 h; Michaelis constant (K_m) went up during 0-12 h, but obviously decreased between 72 to 120 h. In contrast, the effect of root system on the phosphorus transport efficiency in not remarkable, but the phosphorus affinity decreased and gradually returned to normal from 12 h to 120 h when the plants cultivated in P-deficiency solution were transplanted into and stayed in the full Hoagland solution. In addition, the lengths of primary lateral roots in P-deficiency solution were shorter than that of primary lateral roots in full Hoagland solution on the 11th day, and obviously increased from 17th day to 26th day. The results demonstrated that the adaptation of M. hupehensis R. to the condition of phosphorus-deficiency was realized by the changes of parameters of P uptake kinetics during a short time and by the changes of root architecture during a long time.

Key words: Malus hupehensis(Pamp) Rehd., Root architecture, Phosphorus deficiency, Uptake kinetics