大果木莲种子萌发及其生理特性1）

以大果木莲种子为材料，比较赤霉素（ GA3）浸种、磨破种皮和层积40 d种子萌发特性和萌发生理代谢差异，结果表明：冷藏1个月的大果木莲种子在较佳萌发温度25℃／15℃（昼／夜）下，种子萌发率仅为21．33％；当GA3质量浓度达到800 mg· L－1时，种子萌发率均超过53％，且差异不显著，萌发率受温度的影响不大；GA3处理能有效提高在非萌发适温下种子的发芽指数，但对萌发适温下的种子发芽指数无显著促进效果。磨破种皮和层积40 d处理对提高种子萌发率无显著作用。随着萌发进程，800 mg· L－1 GA3处理能显著地提高种子内可溶性糖质量分数和过氧化氢酶（CAT）活性，清除体内的丙二醛（MDA），但对过氧化物酶（POD）活性无明显影响；层积组和对照组种子的可溶性糖质量分数、CAT和POD活性随萌发进程的变化无明显差异，仅在清除MDA的速度上，层积组要优于对照处理。在大果木莲种子萌发的生理代谢变化中，CAT活性与可溶性糖质量分数变化呈极显著正相关，可溶性糖质量分数与MDA质量摩尔浓度、CAT活性与MDA质量摩尔浓度之间均呈极显著负相关；经主成分分析，CAT、POD活性的变化对种子发芽的贡献较大。

Seed Germination and Physiological Characters of Manglietia grandis

We studied the germination characters and physiological metabolism of Manglietia grandis under the GA3-soaked, seed coat-destroyed and 40-d cold stratification treatments .The germination rate of 30-d cold storage seeds reached to 21.33%even under the appropriate temperature .Seeds soaked with GA 3 had higher germination rate which was related with its con-centration and temperature .Seed germination rates were above 53%and had no significant difference under all three tem-perature when seeds were soaked with 800 mgL-1 GA3 .Germination index could be effectively increased in no suitability temperature, but not increased significantly in an appropriate temperature .Germination rate had no significant difference under seed coat-destroyed and 40-d cold stratification treatments .Soluble sugar content and CAT activities were increased effectively and MDA was quickly cleaned under GA 3 treatment, while POD activity was kept stably .But soluble sugar con-tent, CAT and POD activity had no significant difference between cold stratification and contrast treatment , except a quick clearance of MDA in cold stratification .CAT activity had a significant positive-correlation with soluble sugar content .Other-wise, there was a negative correlation between soluble sugar content and MDA content , and between CAT and MDA .By the principle component analysis of four physiological indexes , CAT and POD activity had much more contribution rate to seed germination .