田菁种皮的结构及其与透性的关系

STRUCTURE OF SEEDCOAT OF SESBANIA CANNABINA AND ITS RELATION WITH PERMEABILITY

扫描电镜观察表明:成熟田菁(Sesbania cannabina)种子的种孔闭锁,种脐具有种脐沟,沟下有一网状管胞群,具贮水和通气功能;种皮的结构由外向内依次为表层、栅栏层、骨状石细胞层及薄壁细胞层。作者用多种有机溶剂浸泡、不同时间浓硫酸腐蚀和机械损伤等方法有控制地损伤种脐和/或种皮的不同层次结构,发现表层和种脐不耐腐蚀,栅栏层细胞壁厚,排列紧密有序,并具有酚类物质,是控制水分进入种皮的主要屏障。适度浓硫酸腐蚀和机械损伤是克服种子不透性,提高萌发率的有效途径。文章还讨论了影响种子透性的因素,作用机理及栅栏层中“亮线”的实质。

SEM observation shows that,the micropyle in mature seed is closed,hilum possesses hilar groove under which there is reticular tracheidal bar,which function as for water-storage and permeation.From out inwards the seedcoat includes four layers viz cuticle,palisade,osteos- clereid and parenchymatous layer The structure of hilum and/or seedcoat was damaged by treating the seed with various kinds of organic solvents and concentrated sulfuric acid in dif- ferent durations or by mechanical methods,was found that surface layer and hilum were erosion-nonresistant;the palisades had thick cell walls and were orderly arranged,and con- tain phenols.They are the main barrier controlling the entrance of water through seedcoat. Erosion with concentrated sulfuric acid and mechanical damage of seedcoat are effective me- thods for overcoming its impermeability and raising germination capacity of seeds.The factors effecting permeability of seeds and their control mechanism as well as the nature of“light line”of palisades were discussed.