Influence of different nursery container media on rooting of Scots pine and silver birch seedlings after transplanting.
Scots pine (Pinus sylvestris) and silver birch (Betula pendula) seedlings were grown in containers filled with growing media based on medium-textured sphagnum peat, coarse perlite and fine sand. The seedlings were then planted into fine and coarse sandy soils in 2.2-litre pots, which were subjected to 2 water-content treatments (only one for birch). After the seedlings had grown for 5 wk in a greenhouse, rooting into the surrounding soil and shoot growth were measured. Addition of perlite and sand to peat medium slightly affected rooting, thus suggesting minor effects on seedling establishment. However, nitrogen concentration of the seedlings varied between growing media and correlated positively with rooting into the soil. The particle size and water content of the soil considerably affected rooting of the seedlings. Seedling height at the time of planting did not affect rooting or shoot growth. The fact that the fewest out-grown roots occurred in the dry fine sandy soil, suggests that dry soil together with high strength and resistance to root penetration reduce rooting and water uptake by container seedlings most and may thus cause water and nutrient stresses to seedlings after outplanting.