Cork-oak seedling production : Container capacity and substrate effect on seedling field performance

Cork oak is the second forest species in Portugal covering an area of about 721000 ha. In the context of the Common Agriculture Policy (CAP), large areas (ca. 10% of total area) were reforested between 1994-98 with low survival rates due to inappropriate nursery and establishment techniques, as well as the use of unsuitable genetic material. The main purpose of this study was to evaluate the effect of container capacity and substrate in field performance of cork oak seedling with 1 year of age during the first 3 years after plantation. Therefore 3 container capacities were tested (210, 300 and 400 cm3) in combination with 4 types of substrate: composted pine bark, composted pine bark with vermiculite 3:1(v/v), composted pine bark with peat 1:1 (v/v) and peat with vermiculite 3:1 (v/v). With the 300 cm3 container capacity 3 other substrates were also tested: F+H organic layers, F+H organic layers with composted pine bark 1:1 (v/v) and F+H organic layers with peat 1:1 (v/v). A field trial was established in the South of Portugal in April 1998. Just before plantation seedlings morphological characteristics (root and shoot biomass, leaf area, height, stem diameter, root length and root development patterns) were measured and correlated with survival and growth evaluated one, two and three years after plantation. The results showed that after three years in the field only the type of substrate had a highly significant influence in survival and early growth. Container capacity (210, 300 and 400 cm_) did not have an influence on height growth during the first 3 years, just as there was no clear influence on survival rate. Peat with vermiculite (3:1) substrate led to 30% higher survivals than other substrates. Substrate with peat favoured secondary root development (length), which seems to be an advantage in field performance.