水分胁迫和种子大小对侧柏种子萌发的影响

以山东省石灰岩山地侧柏人工林的种子为材料,研究水分胁迫和种子大小对其萌发的影响。结果表明:随聚乙二醇(PEG)浓度增加,发芽率(Gr)、发芽指数(Gi)和活力指数(Vi)显著降低,平均发芽时间(MGT)显著增加,20%PEG处理的种子发芽率为0。种子休眠率随PEG浓度增加显著增加,死亡率是先降低再增加。胚芽长(GL)、胚根长(RAL)、胚芽/胚根、根长(RL)、根表面积(RSA)和根体积(RV)随PEG浓度增加显著降低。大种子比小种子有着低的死亡率,高的Gr、RAL和RV。PEG浓度和种子大小在发芽率、死亡率、Gi、Vi、GL、RAL、胚芽/胚根、RV有着明显的交互作用。PEG浓度越低,大种子的上述指标优势越大。GL和RAL与Gr、Vi、Gi成显著正相关,与MGT成显著负相关;与RL、RSA、RV成显著正相关。因此,水分胁迫和种子大小是侧柏人工林种子萌发的重要限制因素。

Effects of Water Stress and Seed Size on Seed Germination of Platycladus orientalis

In this study,the effects of water stress and seed size on seed germination of Platycladus orientalis in limestone mountain of Shandong province were studied.The results showed that,with the increase of PEG concentration,the germination rate(Gr),germination index(Gi)and vitality index(Vi)decreased significantly while the mean germination time(MGT)increased significantly,and the germination rate of seeds treated with 20%PEG was 0.Additioanlly,seed dormancy rate increased significantly with the increase of PEG concentration,and the mortality rate decreased first and then increased.Synchronously,the increase of PEG concentration significantly decreased the characteristics of germ length(GL),radicle length(RAL),the ratio of germ to radicle,root length(RL),root surface area(RSA)and root volume(RV).Large size seeds had lower mortality and higher Gr,RAL and RV than small size ones and there were significant interactions between PEG concentration and Gr,mortality rate,Gi,Vi,GL,RAL,the ratio of germ to radicle and RV.The lower the PEG concentration,the greater the advantage of these characteristics above in large size seeds over small ones.GL and RAL were positively correlated with Gr,Vi,Gi,RL,RSA and RV,and negatively correlated with MGT.Therefore,both water stress and seed size were important limiting factors for seed germination of P.orientalis.