Endurcissement au froid et réponse des semis de Juglans nigra transplantés après exposition à différentes modalités de stockage

Abstract

• Effects of overwinter storage regimes on seedling cold hardiness and physiological vigor are relatively unexplored, particularly for temperate deciduous forest tree species. • We evaluated influence of storage duration (0, 66, 119, or 175 d) on electrolyte leakage of stem and root collar tissues following exposure to a series of freeze-test temperatures in black walnut (Juglans nigra L.) seedlings sampled from cold (3 °C) or freezer (−2 °C) storage. Seedlings were subsequently transplanted into a controlled growth chamber environment for two months. • Regardless of storage temperature, mean LT50 was lowest for seedlings stored for 66 d (≤ −34 °C) and increased dramatically after 119 d (≥ −13 °C). • Root collar tissue had lower LT50 than stem tissue after 119 d for cold-stored seedlings, reflecting importance of evaluative tissue type. Days to bud break shortened with increasing storage duration up to 119 d and stabilized thereafter for both storage regimes. Root growth potential was maximized after 119 d of storage, and subsequently declined for cold-stored seedlings. Height growth increased following storage, regardless of duration. • To promote stress resistance and transplant growth response, we recommend that black walnut seedlings from this genetic source be outplanted after approximately 66–119 d of storage.