Low-temperature scanning electron microscopic observations on endosperm in imbibed and germinated lettuce seeds

Abstract

Lettuce (Lactuca sativa L.) seeds were observed using low-temperature scanning electron microscopy (LTSEM). The structure of imbibing and germinating seeds was characterized and compared with that of seeds in which these processes were inhibited by high temperature, far-red irradiation, or polyethylene glycol. Germination is not associated with general breakdown or digestion of the entire endosperm at the micropylar region. Embryos of seeds imbibed in polyethylene glycol, which inhibited germination, appeared to lack turgor and were not able to emerge from the endosperm. Thermal or far-red inhibitory treatments were associated with the appearance of complex membraneous structures in cells of the endosperm and the embryo.Key words: endosperm, germination, Lactuca sativa, lettuce, low temperature scanning electron microscopy, seed.