In central Europe, barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], has commonly been found in humid lowland areas. As a result of the introduction of new crops and farming practices, in the northwest Carpathians, E. crus-galli has spread from lowland (<200 m altitude) to highland (>400 m altitude) areas. We collected seed samples from local populations lying at a distance of approximately 5 km from each other and lined up along transects following the flows of two rivers. The rivers first flow through the valleys separated by mountain ridges and eventually flow into a common lowland. After ripening, the seeds of all populations were germinated at 25 C under long-day conditions. Only the seeds of some lowland populations germinated up to 75%. The frequency of germinated seeds decreased as the altitude where the population was collected increased, and above 200 m above sea level, germination was mostly zero. We then studied the phenological and morphological differentiation of plants from the original (lowland) and recently occupied (highland) areas. Seeds of the lowest and the highest localities lying on the transect of each river were sown in a common garden experiment. In plants from the highland localities, heading and seed dispersal were earlier, while tiller height and tiller mass were lower than in plants from the lowland localities. Seed mass produced per tiller in the lowland and highland plants was similar, and as a result, highland plants allocated a larger proportion of body mass to seed production than did lowland plants. Echinochloa crus-galli populations from highland localities thus produce their progeny earlier and at a lower energy cost than populations from lowland localities. The plasticity of phenological characters likely facilitated adaptation during E. crus-galli spread from lowlands to highlands. Similar adaptations in plant phenology may contribute to the spread of E. crus-galli in other geographic areas.

中文翻译：

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稗草（Echinochloa crus-galli）种群适应性物候性状的地理分化

在中欧，稗草 [稗草(L.) P. Beauv.]，常见于潮湿的低地地区。由于引进了新的作物和耕作方式，在喀尔巴阡山脉西北部，E. crus-galli已从低地（<200 m 海拔）蔓延到高地（>400 m 海拔）地区。我们从相距约 5 公里的当地人群中收集种子样本，并沿着两条河流的流向横断面排列。河流首先流经被山脊隔开的山谷，最终流入共同的低地。成熟后，所有种群的种子在25℃长日照条件下发芽。只有一些低地种群的种子发芽率高达 75%。种子发芽频率随着种群采集海拔的升高而降低，在海拔200米以上，发芽率大多为零。然后，我们研究了原始（低地）和最近占领（高地）地区植物的物候和形态分化。位于每条河流横断面上的最低和最高位置的种子在一个普通的花园试验中播种。高地植物抽穗和播种较早，而分蘖高度和分蘖质量低于低地植物。低地植物和高地植物每分蘖产生的种子量相似，因此，与低地植物相比，高地植物将更大比例的体重分配给种子生产。稗草因此，来自高地地区的人口比来自低地地区的人口更早地生产后代，并且能源成本更低。物候性状的可塑性可能促进了期间的适应E. crus-galli从低地蔓延到高地。植物物候学的类似适应可能有助于E. crus-galli在其他地理区域。