Effect of desiccation during cold storage on planting stock quality and field performance in forest species

Abstract

Seedlings of pedunculate oak (Quercus robur L.), northern red oak (Quercus rubra L.) and Corsican pine (Pinus nigra ssp laricio var Corsicana) were lifted on November 18, January 27 and March 10. They were cold stored for 0, 2 or 4 weeks in desiccating conditions (gunny bags, 1.4°C, 87% RH). An additional treatment consisted in a cold storage for 4 weeks in sealed polythene bags. Root growth potential (RGP), fine root electrolyte leakage (REL) and seedling water status variables were measured. Simultaneously, seedlings were outplanted. The seedlings lifted in November exhibited lower survival and RGP (except in pine) than those lifted in January and March. Cold storage for four weeks in sealed polythene bags did alter water status variables in none of the species, but decreased pine survival. Storage in gunny bags led to a desiccation in all plant components but in pine buds. In pine, RGP and survival after outplanting decreased with desiccation duration. In oaks, and namely pedunculate oak, desiccation lowered RGP, survival and growth after outplanting. In oaks, poor field survival and shoot dieback were associated with low fine root water content measured at the time of planting, and with low RGP. No satisfactory predictor of field survival or growth was found in pine.