Abstract Generally acknowledged reduction of the interspecific hybrid fertility was utilized in evaluation of the putative hybrid swarms of Scots pine (Pinus sylvestris L.) and mountain dwarf pine (P. mugo Turra) viability under field conditions. Pollen viability and seed quality of the trees from the four contact zones of P. sylvestris and P. mugo in Slovakia were compared with the corresponding characteristics of the pure populations of these species from three reference localities. Pollen germination percentage was comparable in contact zones and control populations of the species. Statistically significant differences between the parent and hybrid groups were detected in pollen tube length only. In general, pollen tubes of the pure species populations were longer than those in contact zones. At the cone level, the individuals from contact zones possessed shorter cones than the trees of pure species populations P. mugo and P. sylvestris. This was paralleled by a lower number of seeds per cone in contact zones and higher amount of seeds per cone in the P. mugo population. Striking differences between individuals of the contact zones and reference populations were revealed also in germination potentials of their seeds. Significantly higher proportions of germinating seeds was found in the reference populations of P. mugo and P. sylvestris than in their contact zones. Contrary to seed quality parameters mentioned above, the fractions of filled but non-germinating seeds and amounts of empty seeds were higher in contact zones than in the parental species populations, indicating higher frequency occurrence of abortive embryogenesis in the former. The lower fertility characteristics of the individuals from contact zones indicate their hybrid nature.

中文翻译：

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斯洛伐克樟子松和木松假定杂交群的花粉育性和种子活力

摘要 公认的种间杂种生育力的降低被用于评估大田条件下苏格兰松 (Pinus sylvestris L.) 和山地矮松 (P. mugo Turra) 的假定杂种群的生存力。将来自斯洛伐克 P. sylvestris 和 P. mugo 的四个接触区的树木的花粉活力和种子质量与来自三个参考地点的这些物种的纯种群的相应特征进行了比较。在接触区和该物种的对照种群中，花粉发芽率相当。仅在花粉管长度上检测到亲本和杂种组之间的统计学显着差异。一般来说，纯种种群的花粉管比接触区的花粉管长。在锥体水平，来自接触区的个体比纯种种群 P. mugo 和 P. sylvestris 的树具有更短的锥体。与此平行的是接触区中每个锥体的种子数量较少，而 P. mugo 种群中每个锥体的种子数量较多。接触区个体和参考种群之间的显着差异也体现在其种子的发芽潜力上。在 P. mugo 和 P. sylvestris 参考种群中发现的发芽种子比例明显高于它们的接触区。与上述种子质量参数相反，接触区中饱满但未发芽的种子和空种子的比例高于亲本物种种群，表明前者发生失败胚胎发生的频率更高。