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RESEARCH PRODUCT

Qualité et performance de plants de Douglas soumis à différentes contraintes hydriques

subject

description

An experiment was carried out on 12 Douglas fir seedlings lots that were 3 years old and had all originated from the same seed lot. Treatments consisted in combining stock type with three different height to diameter ratios, storage duration and method (long at 2°C or short in various conditions), and protection from desiccation (by bagging or not). Seedling lots were assessed at planting by root electrolyte leakage (REL), root moisture content (RMC) and predawn shoot water potential (Ywp). They were planted simultaneously in well-watered or water-stressed conditions. Performance level was based on survival and height growth at the end of the growing season. Slender seedlings not bagged had the lowest values of RMC, Ywp and field performance. The sturdier stock type was less sensitive to desiccation and had 100% survival, in all stress conditions. In contrast to RMC and Ywp, REL was not influenced by stock type. RMC and Ywp values were highly correlated, on a seedling basis as on a batch basis. RMC was the best predictor of the field performance parameters (survival and growth for both water regimes) which were all well correlated. Moreover, lower stock quality resulted mainly in slower growth in the well-watered field trial, and in poor survival under drought conditions.