周健　代松　钱存梦　苏友谊　李淑娴

(南京林业大学，南京，210037)



大花四照花种子休眠解除过程中种皮和胚乳结构变化1)

周健代松钱存梦苏友谊李淑娴

(南京林业大学，南京，210037)

摘要为探讨种皮、胚乳对大花四照花种子萌发的影响，以不同解除休眠处理后大花四照花种子为材料，开展了种皮透水性试验，并分别对其种皮和胚乳进行了扫描电镜(SEM)和透射电镜(TEM)观察。结果表明：大花四照花种皮存在透水性障碍。扫描电镜观察发现，其种皮由外到内依次为表皮层、栅栏层、薄壁细胞层以及纤维细胞层。表皮层由多层排列紧密的厚壁细胞组成。栅栏层则由单层紧密排列的长柱状大石细胞构成，栅栏层可能是阻碍种子吸水的主要原因。酸蚀和低温层积对种皮结构都会产生一定影响。低温层积处理能破坏种皮表层结构，同时还能改变内部栅栏层细胞结构，种子低温层积90 d后，种皮出现裂缝直达内部薄壁细胞层。透射电镜观察发现，低温层积过程中，胚乳细胞内大分子营养物质不断降解，细胞内物质代谢速度逐渐加快，低温层积90 d，营养物质基本降解，线粒体、内质网、高尔基体等细胞器相继出现，种子休眠解除。浓硫酸酸蚀能加快大花四照花种皮结构的改变和胚乳细胞内物质代谢，促进该种子休眠的解除。

关键词大花四照花；种子休眠；种皮；胚乳；细胞结构

分类号S722.1

Ultrastructure Changes of Seed Coat and Endosperm onCornusfloridaSeed during Dormancy Breaking//

Zhou Jian, Dai Song, Qian Cunmeng, Su Youyi, Li Shuxian

(Nangjing Forestry University, 210037 Nanjing, P. R. China)//Journal of Northeast Forestry University，2016,44(5)：34-38.

In order to investigate the effect of seed coat and endosperm on the germination ofCornusfloridaseeds, the ultrastructure of seed coat and endosperm ingredients ofC.floridaseed with different treatments was systematically investigated by using scanning electron microscope (SEM) and transmission electron microscope (TEM), combining with the study of water permeability. Results of water uptake revealed the seed coat ofC.floridcould retard water uptake. By SEM images, from the exterior to the interior, the seed coat ofC.floridconsisted of four layers: the epidermal layer, the palisade layer, the parenchymatous layer and the fibrocyte layer. The epidermal layer consisted of multilayer sclerenchymatous cell. The palisade layer consisted of a monolayer macrosclereids with thick walls elongated longitudinally, and it may be the main barrier controlling the entrance of water through seed coat. Both of cold stratification and acid etching could change the seed coat structure ofC.florid. The epidermal layer and the palisade layer ofC.floridseed coat were damaged after treated by concentrated sulphuric acid. Cold stratification could destroy the out layer ofC.floridseed coat and change the structure of palisade layer to some extent. When seeds were cold stratified at 5 ℃ for 90 d, the cracks were appearing through the epidermal layer and the palisade layer. By TEM, with theC.floridseed dormancy released, macromolecule nutrients in the endosperm gradually decomposed and metabolism boosted. When seeds were cold stratified for 90 d, nutrients in the endosperm gradually decomposed, mitochondria, endoplasmic reticulum, golgi apparatus appeared, and its dormancy was broken. In addition, proper sulfuric acid treating could accelerate the break ofC.floridseed dormancy by expediting the change of seed coat structure and the metabolism of endosperm cell.

KeywordsCornus florida; Seed dormancy; Seed coat; Endosperm; Cell structure

大花四照花(Cornusflorida)为山苵萸科(Cornacease)山茱萸属(Cornus)四照花亚属落叶乔木，又名多花梾木，多花狗木。大花四照花原产于北美洲东部，喜湿润半阴的环境，早春开花，伞形花序，野生种外面的4个苞片刚开始开放时为绿色，后逐渐变为白色，为适应观赏的需要，又培育出苞片为粉红色或大红色的品种。……