In this study, we investigated the influence of cold stratification on seed germination in S. × niederederi, a hybrid between the North American S. canadensis and the European S. virgaurea, using fruit samples collected in 2016 in Poland. We aimed to test the hypothesis that the low temperature exposure decreases the final percentage and speed of seed germination in the hybrid and its parental species. For each species, sets of 100 achenes in three replications were mixed with dry sand and stored in Petri dishes in darkness for 12 weeks, at -18 °C and + 4 °C, and + 25 °C. The seeds were incubated for 21 d at room temperature (+25 °C), under the 12 h photoperiod (630 lx). We showed a lack of significant differences in: (i) the final percentage of germinated seeds of studied species stored at the same conditions, (ii) the final percentage of germinated seeds between the applied stratification conditions in the hybrid and its parental species, and (iii) the mean values of Timson's index, mean germination time, and coefficient of velocity of germination between the stratification conditions in each species. The statistically significant inter-specific differences in the mean germination time parameter after the +25 °C treatment suggest that the seeds of S. × niederederi are able to germinate faster than the seeds of its parental species. However, to improve our knowledge of naturalization and invasion abilities of S. × niederederi by sexual reproduction, the seed germination and seedling survival of the hybrid should be tested in the field.

中文翻译：

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冷复层对一枝黄花（藜科）及其亲本种子萌发的影响。

在这项研究中，我们使用了2016年在波兰收集的水果样本，调查了冷分层对S.×niederederi（北美S.canadensis和欧洲S.virgaurea之间的杂种）的种子发芽的影响。我们旨在检验以下假设：低温暴露会降低杂种及其亲本物种的种子萌发的最终百分比和速度。对于每个物种，将三套重复的100株瘦果与干燥的沙子混合，并在黑暗中的陪替氏培养皿中于-18°C，+ 4°C和+ 25°C下储存12周。将种子在室温下（+25°C）在12 h光周期（630 lx）下孵育21天。我们发现以下方面没有显着差异：（i）在相同条件下存储的已研究物种的最终发芽种子百分比，（ii）杂种及其亲本物种在所应用的分层条件之间的发芽种子的最终百分比，以及（iii）每个物种的分层条件之间的Timson指数，平均发芽时间和发芽速度的平均值。+25°C处理后，平均发芽时间参数的统计上种间差异具有统计学意义，表明S.×niederederi的种子比其亲本物种的种子发芽得更快。然而，为了提高我们对有性繁殖的S.×niederederi的归化和入侵能力的了解，应该在田间测试杂种的种子发芽和幼苗存活。（iii）每个物种分层条件之间的Timson指数平均值，平均发芽时间和发芽速度系数。+25°C处理后，平均发芽时间参数的统计上种间差异具有统计学意义，表明S.×niederederi的种子比其亲本物种的种子发芽得更快。但是，为了提高我们对有性繁殖的S.×niederederi的归化和入侵能力的了解，应在田间测试杂种的种子发芽和幼苗存活。（iii）每个物种分层条件之间的Timson指数平均值，平均发芽时间和发芽速度系数。+25°C处理后，平均发芽时间参数的统计上种间差异具有统计学意义，表明S.×niederederi的种子比其亲本物种的种子发芽得更快。但是，为了提高我们对有性繁殖的S.×niederederi的归化和入侵能力的了解，应在田间测试杂种的种子发芽和幼苗存活。+25°C处理后，平均发芽时间参数的统计上种间差异具有统计学意义，表明S.×niederederi的种子比其亲本物种的种子发芽得更快。但是，为了提高我们对有性繁殖的S.×niederederi的归化和入侵能力的了解，应在田间测试杂种的种子发芽和幼苗存活。+25°C处理后，平均发芽时间参数的统计上种间差异具有统计学意义，表明S.×niederederi的种子比其亲本物种的种子发芽得更快。然而，为了提高我们对有性繁殖的S.×niederederi的归化和入侵能力的了解，应该在田间测试杂种的种子发芽和幼苗存活。