Changes in desiccating seeds of temperate and tropical forest tree species
Abstract
The physiological basis of seed recalcitrance is as yet unknown. Hypotheses suggesting possible causes have been proposed but the end result is that intact recalcitrant seeds cannot be stored for long periods of time. Thus, if the seed crop of a recalcitrant species fails, nurseries will be unable to draw upon a storage reserve of seeds in order to meet the demands of growers. A series of experiments on both temperate and tropical recalcitrant-seeded tree genera were initiated with the goal of relating changes in the physiology, biochemistry, and ultrastructure of desiccating seeds to loss of viability. Two tropical species, Carapa guianensis Aubl. and Guarea guidonia (L.) Sleumer (American muskwood) and two temperate species of oak, Quercus nigra L. (water oak) and Quercus alba L. (white oak) were selected for our experiments. This paper summarizes results obtained over a 7-year period.