Forest tree seedlings grown in containers must have appropriate biometric parameters essential for crop growth. Other criteria are also important, including the ability to transport seedlings with a root ball over both short and long distances. Transport of seedlings with a root ball takes place in containers and, after being pulled out in transport containers or by hand holding the seedling. It is important that the root ball, once removed from the container, is not susceptible to damage such as tearing, deformation, or scattering. A prototype station was used to simulate mechanical impacts on the root ball, reflecting transport conditions. Tests were conducted on the main forest−forming species in Poland: pine, beech, and oak seedlings, 90 for each species. The seedlings were grown in a peat−perlite substrate in containers made of polystyrene with a single cell volume of 145 cm3 Pinus sylvestris and 275 cm3 Fagus sylvatica and Quercus robur. Differences were observed in the percentage of root ball part loss depending on the species and container type. Pine root balls were the most susceptible to damage, followed by beech and then oak. Root balls from containers with a volume of 275 cm3 were less prone to damage than those from 145 cm3. A correlation was found between the percentage of root ball loss and seedling shoot height, root collar diameter, and degree of root overgrowth also for pine and beech with moisture of substrata. For pine seedlings with shoot heights under 4 cm and root collar diameters under 1.2 mm, root ball loss exceeded 30%. When producing small pine seedlings on peat perlite substrata, it is probably better to use containers with smaller cell volumes to reduce the risk of damage during transport, which is connected with the ability of a smaller root system to outgrow a smaller cell.
Kormanek et al. (Thu,) studied this question.