科研之友
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摘要
eugenia pyriformis camb. is a tree species of medium height that produces savory fruits with large thin-coated seeds. these seeds quickly lose viability when submitted to desiccation. our aim was to investigate embryo structure in e. pyriformis seeds and the ultra-structural changes that result from drying, germination and storage. the axis was less than 1.0 mm long, while the fleshy cotyledons varied from 1.0 to 2.0 cm. the apical and radicular meristem lie in opposing positions. there is a procambium and a medulla of parenchymatous nature, rich in starch grains. leafy primordia were identified around the stem meristem and there were unicellular trichomes and stomata on the adaxial epidermis of the cotyledons. the gradual desiccation of the seeds provoked cellular structure disarrangement, which also occurred as the seeds aged. apical meristem form changed from concave to conical during germination and the radicular hypocotyl axis became elongated, with root protrusion. in this phase, the cells have structured content and hydrolysis of reserves. seed water content variation was evaluated and the physiological consequences of this change are discussed.
