大叶藻(Zostera marina L.)胚的结构和种子萌发过程的研究

Study on Embryo Structure and Seed Germination of Zostera marina L.

以采自山东荣成褚岛桑沟湾南岸成熟的大叶藻种子为材料,研究了种子的外部形态特征、胚乳成分及胚的解剖结构,并初步了解了大叶藻种子的萌发过程。结果表明,大叶藻种子是单子叶有胚乳的种子,呈暗褐色,椭圆形或长圆形,种皮革质且有17～20条纵肋,胚乳丰厚坚硬,胚乳细胞被淀粉粒充满;胚弯曲,由胚根、胚轴、胚芽和子叶组成,子叶U形棒状,其弯曲部有一裂缝,胚芽位于裂缝处,胚轴较短,其下是两个对生的胚根,有中央维管束贯穿胚根、胚轴、胚芽和子叶。在子叶出土萌发的植物类型中,大叶藻种子萌发过程是罕见的。萌发初期,子叶优先生长突破种皮而长出地面,此后胚根才开始生长并产生不定根。对大叶藻种子结构和萌发过程的研究,为探讨大叶藻种子萌发和幼苗更新的限制因素提供了一定的理论依据。

Seed morphological character, endosperm components and embryo structure of the Zostera mari- na L. were studied using the materials collected from south bank of Sanggou Bay, Rongcheng Zhudao in Shandong province. The process of the seed germination was also studied in this paper. The results showed that Zostera marina L. is monocotyledon. The testa is leathern and has17-20 longitudinal ribs. Its seed contains dark brown endosperm in ellipse or egg-shape. The endosperm is rich and hard, filled with starch grain. The embryo is curve and composed of radicle, hypocotyl, embryo bud and cotyledons. The cotyledons showed in U-shaped rod with embryo bud in its gap of the curved part. The hypocotyl is a little short and two opposite radicles were located underside. The central vascular bundle runs through the em- bryo. The seed germination process is exceptional among the epigaeous plants. In the early germination stage, the cotyledons break through the testa and grow up out of the ground, thereafter, the radicles begin to grow and produce adventitious roots. This study provided a theoretical basis for further studies on limit- ing factors of seed gemination and seedling of Zostera marina L..