银杏种实发育的解剖和超微结构观察

Observation on Anatomical and Ultra-Structure of Seed at Different Development Phases in Ginkgo biloba

以银杏核用主栽品种佛指、洞庭皇和龙眼为材料,通过半薄切片和扫描电镜观察,研究种实的发育过程及其结构变化。结果表明:①银杏种实单核重与纵、横径的生长变化相似,单核重的主要生长期比纵、横径多4～9 d,佛指单核重的主要生长天数比洞庭皇和龙眼分别多3和5 d。②随着种实的发育,细胞体积由Ⅰ、Ⅱ、Ⅲ到Ⅳ期不断增大,单位面积内的细胞数逐渐减少,细胞形状也发生变化。③中种皮在Ⅱ期开始木质化,在Ⅲ期细胞核趋边化时,发育速度加快,Ⅳ期深度木质化,此后种实生长开始减缓并趋于停止。其中龙眼的中种皮发育最早。④种壳管胞直径由大到小依次为龙眼、佛指、洞庭皇。中种皮的形状和木质化影响种实的发育及种壳的管胞结构。

Development process and structure changes of seed were studied by semithin slice and scanning electronic microscope (SEM) with Fozhi, Dongtinghuang and Longyan, which were the major seed-purpose cultivars in Ginkgo biloba. The results were as follows; ① Changes of increase of stone weight were similar with that of length and diameter of seed; the main growth period of stone weight was 4 to 9 d longer than that of length and diameter; and the main growth days of stone weight of Fozhi were 3 and 5 d longer than that of Dongtinghuang and Longyan respectively. ② With development of seed, size of cells expanded from phase I to IV , numbers per unit area gradually decreased, and cells shape also changed. ③ Lignification of mesocoat began at phase II, quickened at phase 1 when the nucleolus appeared moving to the edge of cells; the process was significant at phase IV , following which the growth of seed became slower and tended to stop. The mesocoat development of Longyan was the earliest. ④ The diameter of tracheid of seed chaff was Longyan>Fozhi>Dongtinghuang in order, the shape and lignification of mesocoat affected the development of seed and the tracheid structure of seed chaff.