Dynamics of nutrient absorption in root systems of Populus×xiao zhuanica and Robinia pseudoacacia

The nutrient absorption of N,P and K in root systems of Populus×xiaozhuanica and Robinia pseudoacacia is analysed by a dynamic methodology.The results show that: 1) NH-4~+ affinity for Populus×xiaozhuanica is weaker than that for Robinia pseudoacacia;the rate of NH-4~+ flowing into Populus×xiaozhuanica is slower than that flowing into Robinia pseudoacacia;the maximum absorption rate of NH-4~+ by the root system of Populus×xiaozhuanica is much higher than that of Robinia pseudoacacia;compared with Robinia pseudoacacia,Populus×xiaozhuanica has a stronger absorbency for and resistance to a deficiency in NH~+-4.2) the rate of H-2PO-4~-flowing into Robinia pseudoacacia is higher than that of Populus×xiaozhuanica;Robinia pseudoacacia has a stronger H-2PO-4~-deficiency resistance than Populus×xiaozhuanica.3) although differences exist between Populus×xiaozhuanica and Robinia pseudoacacia in the dynamic characteristics of the ability to absorb K~+,competition does not occur when the two species are planted together.Populus×xiaozhuanica and Robinia pseudoacacia share a complementary and harmonious relation in the absorption of N and P nutrient elements.