Abstract: The uptake of phosphorus in three different types of roots system (absorbing roots，growing roots and brown roots) of M. hupehensis Rehd. was affected by three kinds of organic materials and was in accordance with Michelis-Menten equation. Treatment with various kinds of organic materials changed the uptake kinetics parameters of 32P to different extent. The addition of organic materials increased Imax and decreased Km as compared with the control. The value of Imax of three kinds of roots was in the following orders: treatment with chicken manure > sheep manure > peanut straws in summer, and treatment with sheep manure> chicken manure > peanut straws in autumn (value of Km was in the opposite order). Imax and Km of the three types of roots were determined and it was found that Imax of absorbing roots was 7.4 to 8.7 times that of brown roots, and Imax of growing roots 4.7 to 5.8 time as large as that of brown roots. Km of brown roots was 1.1 to 1.5 times and 1.0 to 1.2 times those of absorbing roots and growing roots. This means that the potential P uptake efficiency and affinity in absorbing and growing root was greater than that of brown roots. The Imax was positively correlated with plant biomass in summer while showed no great significance in autumn.

Key words: Malus hupehensis Rehd., Organic material, Root system, 32P, Absorption dynamic parameter