Container effects on growth and biomass allocation in Quercus robur and Juglans regia seedlings

Abstract

Container size and shape impacts biomass allocation of nursery seedlings. Effects of different pot types on shoot and root growth and biomass allocation were evaluated in nursery cultivation of Quercus robur L. and Juglans regia L. We compared two containers currently used in Italian forest nurseries (ISSA-pot®; Plastecnic®) and two alternative types (Superoots Air-pot®; Tubex®); different pot sizes were also included: two for ISSA-pot and Plastecnic; four for Air-pot. Seedlings were evaluated during 1-year nursery growth and biomass allocation was determined on a sub-sample at the end of the growing season. For both species, seedlings grown in larger containers generally grew more and containers >4.5 l produced the largest seedlings. Root biomass was >50% of total biomass in all containers with the tap-root comprising the major root system component. Air pruning in the Air-pots inhibited seedling growth of both species in narrow deep pots, while in bigger sizes (wide and deep) it produced positive responses, especially for walnut. Container configuration differentially affected the studied species: shoot and root system development of walnut seedlings was more limited by pot diameter than depth. Q. robur had improved shoot and root system development when grown in Tubex.