巴西橡胶树果皮及种皮的发育

Development of Pericarp and Seed Coat of Hevea Fruit

描述巴西橡胶树果皮和种皮在各个不同发育时期的解剖结构。（1）授粉后约120d，果皮和种皮发育成熟。（2）果皮由子房壁发育形成。授粉30d后，果皮可区分为外果皮、中果皮和内果皮三层结构。外果皮由表皮和表皮下7～8层绿色扁平细胞构成，中果皮由等径薄壁细胞构成，其上分布维管束及密集成群的初生乳管，内果皮由三层走向不同的长形细胞组成。授粉后60～70d，内果皮细胞开始木质化。果实成熟时，外中果皮革质而干燥，内果皮发育成为木化坚硬的果壳。（3）种皮由外种皮和内种皮构成。外珠被发育成薄膜状外种皮，部分表皮细胞含有色素，含色素的表皮细胞与不含色素的表皮细胞相间排列，形成外种皮上的花纹，表皮外壁有一蜡质层。内珠被发育成内种皮。授粉60d以后，内珠被细胞开始分化：内珠被外表皮细胞呈辐射状伸长并木质化，成为栅栏状厚壁组织，以后发育成坚硬的“种壳”，内珠被外表皮以内的组织发育成为疏松的薄壁组织，呈海绵状附在种壳内面。

The fruit and seed of Hevea brasiliensis mature 120 days after pollination. Pericaop of the fruit derived from ovary wall can be divided into three distinctive parts,exocarp,mesocarp and endocarp after 30 days of pollination- The exocarp consists of epidermis and 7 to 8 layers of 8reen flat cells below the epidermis. The mesocarp is made upof parenchyma where vascular bundles and clusters of primary laticifers were observed.The endocarp is composed of three layers of long cells arranged in different directions.The wall of endocarp cells begins to thicken 65-70 days after pollination. When the fruitmature,the exocarp and mesocarp become dry and leathery,while the endocarp developsinto lignified hard shell of the pericarp.The seed coat composed of outer seed coat and inner seed coat. outer seed coat isdeveloped from the outer integument. Epidermis of the outer seed coat is spotted becausesome clusters of epidermal cells contain pigment scattering between the colourless cells ofthe epidermis. The outer tangential wall of epidermal cells is coated with a waxy substance. The inner seed coat is developed from inner integument which begins to differentia te 60 days after pollination. The outer epidermal cells of inner integument are elongated along the anticlinal axis and their walls become thicker,forming palisade sclerenchyma as a result. The sclerenchyma eventually becomes a hard layer of seed coat. The cellswithin outer epidermis of inner integument develop into a loosely spongy parenchymalying under the hard seed coat.