5种苏铁属极小种群植物种子生物学特性研究

Study on Seed Biological Characteristics of Five Cycas Species with Extremely Small Population Distributed

目的:探讨环境因子对5种濒危苏铁属种子发芽的影响,揭示其种子发芽特性及其濒危机制。方法:以5种苏铁种子为试验材料,研究了5种苏铁种子的形态特性以及不同温度、光照、水分、基质条件下种子发芽特征。结果:不同种类的苏铁种子性状存在一定差异,长叶苏铁种子相对较大,横径、纵径、棱径和单果重值最大。5种苏铁种子发芽率较高,但不同种类的苏铁种子发芽率存在差异,叉叶苏铁种子发芽率最高,达92.73%,长叶苏铁种子发芽率最低,为75.39%。环境条件对苏铁种子的发芽影响较大,温度过高或过低均不利于种子发芽,苏铁种子发芽的适宜温度为25~30℃;苏铁种子发芽对水分条件要求较高,随着PEG 6000浓度的增加种子发芽受到的抑制作用不断加强,在浓度为20%时达到完全限制其发芽的阈值;苏铁种子发芽需要适宜的光照,40%~60%的光照条件最有利于种子发芽;苏铁种子发芽对基质条件没严格的要求,但在土质疏松、透气性好的基质中更有利于种子发芽。结论:5种濒危苏铁属植物种子发芽对水分、温度和光照条件有一定的适应范围,适宜的水分、相对光照度40%~60%、温度25~30℃为苏铁种子萌发的最适条件。

Objective:The biological characteristics and the effects of different environmental factors on seed germination of five Cycas species with extremely small populations were explored.Methods:The morphological characteristics and germination index were determined.Moreover the seed germination characteristics were studied under different texts of temperature,light,water and growing media.Results:There were some differences in seed traits of five Cycas species.Among them,the seed of Cycas dolichophylla was the biggest,with the biggest transverse diameter,longitudinal diameter,edge diameter and seed weight.The germination rates of five Cycas species were generally high and different.The seed germination rate of Cycas bifida and Cycas dolichophylla were the highest and the lowest,92.73%and 75.39%respectively.The proper temperature for seed germination ranged from 25℃to 30℃.With the increase of PEG 6000 concentration,the inhibition of seed germination was strengthened,the seed could not germinate under the treatment of 20%concentration.The 40%to 60%of the whole light were favorable for the seed germination.Loose growing medium with good air permeability was suitable for the seed germination of Cycas.Conclusion:Five Cycas species had the specific adaptability to the ecological factors,the optimum conditions for seed germination of Cycas were suitable moisture,relative light 40%to 60%and temperature 25℃to 30℃.