Acid phosphatase activity in mycorrhizal and non-mycorrhizal Scots pine seedlings in relation to nitrogen and phosphorus nutrition

Mycorrhizal and control seedlings of Scots pine (Pinus sylvestris L.) were grown under axenic conditions at various concentrations of nitrogen (0.17 mM, 3.78 mM, 18.92 mM) and phosphorus (0.25 mM, 5.58 mM, 23.5 mM). Enzyme activities of soluble acid phosphatase of excised roots (surface-accessible activity) and of crude enzyme preparations of root tissue (total soluble activity) were analyzed in control and mycorrhizal seedlings. The content of P in pine shoot was also measured. The intermediate supply of nitrogen and phosphorus (N = 3.78 mM, P= 5.58 mM) was optimal for development of ectomycorrhizae. Activity of acid phosphatase was stimulated by higher levels of N in the soil and was higher in mycorrhizal than non-mycorrhizal roots. Pine roots had greater acid phosphatase activity at the reduced than at the higher P concentrations. The presence of mycorrhizae increased the activities of both surface-accessible and total soluble enzyme activities at lower P supply (0.25 mM, 5.58 mM) and decreased it significantly at the highest P concentration (23.5 mM). P content in shoots was higher in mycorrhizal than non-mycorrhizal seedlings.