Abstract:
To reveal whether the testa and endosperm are main factors restricting the seed germination of Sinopodophyllum hexandrum,anatomical structure of seed in different germination stages(1,7,14,21 and 28d)of S.hexandrum were observed by using the tissue sectioning microscopy,and morphological characteristics of plants were investigated after the germination seeds sowing 7-210 d.The seed of S.hexandrum was composed of testa,endosperm and embryo.The testa contained episperm and endopleura,the episperm was compact and regular and it was composed of palisade cells and epidermal cells from outside to inside,and the endopleura was composed of 5-6 layers sponge cells.The endosperm accounted for most of the seed,included micropylar endosperm and outer endosperm.The embryo consisted of radicle,hypocotyl and cotyledons,surrounded by the compacted testa,multilayer-micropylar endosperm and outer endosperm.During the germination stage,the radicle and hypocotyl began to elongate from 1-7 d,two cotyledons separated from 7-14 d,the radicle broke through the micropylar endosperm and testa from 14-21 d,the radicle,hypocotyl and cotyledons continued to expand and elongate from 21-28 d.3 function leaves and 5 adventitious roots were formed on average after seeding for 210 d.The compacted testa(physical dormancy)and multilayer endosperm(mechanical dormancy)were the two main factors that restricted seed germination of S.hexandrum.