Effects of partial removal of seed reserves on some aspects of seedling ecology of seven dune species
Greenhouse studies were conducted to determine the effects of partial removal of endosperm or cotyledons from seeds of seven dune species on seed germination, seedling emergence, seedling size, and dry matter allocation. Different proportions (0, 30, and 60%) were surgically removed from seeds of Agropyron psammophilum, Calamovilfa longifolia, Elymus canadensis, Leymus arenarius, Panicum virgatum, Lupinus perennis, and Strophostyles helvola. Partial removal of seed reserves caused a significant reduction in seedling variables 1 or 2 weeks after planting in sand. For example, seedling height, leaf area, dry weight of leaves, stem, and roots were significantly lower than control. The data suggest that the principal determinant of seedling size at an early stage was the amount of energy reserves in the endosperm or cotyledons of seeds. In addition to reduction in food reserves, partial removal of seed reserves caused some physiological damage to seedlings. In grass species, seedlings from surgically treated seeds devoted more dry matter to the roots and less to the leaves and stem than control seedlings. In dicot species, however, plants from treated seeds devoted more dry matter to the leaves and less to the roots. Key words: seed injury, seed germination, seedling size, energy allocation, dune plants.