Transplant timing affects first-season root growth of Turkish hazelnut (Corylus colurna L.)

Rapid posttransplant root growth is often a determining component of succes sful establishment. This study tested the effect of transplant timing on fi rst-season root growth dynamics of bare-root Turkish hazelnut trees. Trees were either harvested and planted in the fall (F-F), harvested in the fall and planted in the spring after holding in refrigerated storage (F-S), or h arvested and planted in the spring (S-S). All trees were transplanted into 51-L containers, adapted with root observation windows. Root growth began i n F-F and F-S trees 1-2 weeks before spring budbreak, but was delayed in S- S trees until approximate to3 weeks after budbreak. Budbreak was 6 days ear lier for fall-harvested than for spring-harvested trees. No new roots were observed before spring. Root length accumulation against observation window s (RL) was delayed for S-S trees, but rate of increase was similar to F-F a nd F-S trees soon after growth began. Seasonal height, trunk diameter growt h, and RL were similar among treatments. Surface area of two-dimensional pi ctures of entire rootballs was not correlated with seasonal RL.