西南桦自由授粉子代适应性与斑块大小、遗传多样性间的相关性

以位于广西靖西土石山生态交错区的9个西南桦斑块为研究对象,通过种子收集、种子萌发与幼苗培育试验,揭示西南桦子代适应性与斑块大小、遗传多样性间的关系.结果表明,种子重量与种子萌发率、胚根长、芽苗长呈极显著正相关(p＜0.01),而仅与移苗后2个月时的苗高及移苗后5个月时的地径呈显著正相关(p＜0.05),说明种子萌发阶段母本效应很明显,而在幼苗生长阶段母本效应逐渐减弱；种子千粒重、萌发特征、幼苗生长表现指标与斑块大小、遗传多样性指标大多呈不显著相关(p＞0.05)或呈显著负相关,而且各石山斑块跟土山大斑块间的地理距离与相应斑块的子代适应性指标大多呈负相关,说明斑块间存在强烈的花粉流,这种相关性规律是斑块大小以及斑块间地理距离等因素共同作用的结果.

Preliminary Report on Offspring Fitness in Relation to Patch Size and Genetic Diversity of Betula alnoides in A Heterogenous Landscape

Relationship between offspring fitness and patch size and genetic diversity of Betula alnoides was investigated through trials of seed germination and seedling growth with seeds collected from nine patches of this species in an ectone of two types of soils originated from limestone(site L) and granite(site G) at Jingxi County,Guangxi.The results showed that seed mass had significantly positive correlation to ratio of germinating seed,length of radicle and whole little seedling,and only to seedling height in two month and collar diameter in five month after transplanted,which inferred that maternal effect existed remarkably at stage of seed germination,while became less obvious at stage of seedling development.The majority traits of offspring fitness were not significantly related to,or remarkably negatively related to patch size and genetic diversity,and geographic distances between patches at site L and the big patch at site G were mostly negatively related to their offspring fitness,this was due to the fact that there existed strong pollen flows between patches,and this kind of relationship resulted from joint effects of many factors such as patch size,distance between patches.