pH influence on root growth and nutrient uptake of Pinus pinaster seedlings

Two-week old Pinus pinaster seedlings were grown at four pH values ranging from 3.5 to 6.5. Root elongation rate progressively decreased with the duration of treatment at 3.5 and 6.5 pH. After 4 weeks 3.5 pH gron roots showed the lowest lenth and the highest biomass because of their marked thickening. The pH of the culture solution did not influence lateral root initiation, whereas it affected their length, that was highest at 3.5 pH and lowest at 6.5 pH. Mineral nutrition was affected by the pH of the culture solution. The P, Fe and Al concentration in roots was higher in the 3.5 pH and 4.5. pH solutions. On the contrary a lower K, Ca, Mg and especially Mn content of roots was measured in the 3.5 pH grown seedlings. These results suggest that P pinaster is able to grow on a wide range of acidic soils changing the morphology of the root system in relation to soil conditions.