Consequences of cutting off distal ends of cotyledons of Quercus robur acorns before sowing

Abstract

Production of seedlings, especially in containers, requires simultaneous germination and emergence. Mechanical scarification often speeds up the growth of embryo axes, increases the percentage of germinating seeds and seedling emergence. Cutting off the distal ends of cotyledons is a mechanical scarification technique sometimes used in the container production of oak seedlings. However the consequences of this procedure for seedling development are little known. We wanted to determine these effects on development and metabolic changes of pedunculate oak (Quercus robur L.) seedlings. The majority of seedlings from acorns with cut cotyledons emerged two weeks earlier, more simultaneously and their total emergence (due to rejecting spoiled acorns) was ca. 20% higher. The main result is that the strong damage to cotyledons (more than one fifth of acorn mass) caused a decrease of seedling height and mass even after the second growing season. Negative consequences on seedling root/shoot ratio or on their metabolism were not observed. We conclude that this method is useful for seedling production in containers when acorn mass is reduced by one fifth.