Effects of acorn storage duration and parental tree on emergence and physiological status of Cork oak (Quercus suber L.) seedlings

This study was conducted to evaluate how parental trees and seed storage duration influenced subsequent seedling physiological status and growth. Seedling emergence rate was higher than 90% independently of the duration of seed storage or parental trees. Seed storage shortened significantly the time and increased the uniformity of seedling emergence. Consequently, the delayed seedling emergence from fresh seeds could be explained by epicotyl dormancy. Seed size varied with parental tree. Seedling growth rate was greatly affected by seed size, independently of storage treatment. Seedlings originating from large seeds (> 5 g) had the fastest growth rates and seedlings from the smallest seeds (< 4 g) had the slowest. Final shoot height, however, depended on the duration of seed storage. The seed size and the duration of storage had a great effect on the initial rate of leaf production, but did not affect the final number of leaves. Leaf chlorophyll concentration was reduced as the duration of seed storage increased but was independent of parental tree (i.e., seed size). Seedling biomass was positively related to seed size. The duration of seed storage reduced the shoot/root ratio, but no significant effect was observed among parental trees. The shoot/root value of seedlings from stored seed was about 1.5 and the one of seedlings from fresh seed was about 2.