Walnut cultivar performance of cold resistance in south central France

In south-central France, walnut exhibited freezing tolerance by acclimation in the fall and deacclimation in the spring. The cold hardiness level varied with the different cultivars and dates. Cold tolerance performances of 7 walnut fruit cultivars (Chandler, Franquette, Fernor, Fernette, Lara, Pedro, Serr) and of the hybrid Juglans regia × Juglans nigra NG38 were compared in the same location, at the INRA Center of Clermont-Ferrand. For these comparisons, an electrolyte leakage conductivity method (LT50) was used and adapted for walnut.In all cases NG38 (Juglans regia × Juglans nigra) appeared particularly cold resistant