Field trials containing 8–10 sycamore seed sources were established on ‘farm woodland’ sites in 1992 to identify the most productive and adapted seed sources for use in lowland Great Britain. Early results from these trials found little difference among provenances for growth traits. To guide the next steps of sycamore improvement in the British Isles, three of the five original trials have been revisited and assessed for variation in growth and form at 27 years, which is between one-third and half rotation age. There were large differences in growth among sites but differences among provenances were small or non-significant and showed no interaction across sites. Spring phenology evaluation from one of the trials demonstrated that timing of bud burst was negatively associated with latitude which was the only trait providing any evidence of adaptive differentiation among provenances. However, the effect was small and driven by much later flushing of French and German seed sources than British seed sources. Given the lack of clear provenance differentiation and qualitatively similar rankings across sites, we found no justification for subdividing Britain into breeding zones for sycamore at this stage, nor for excluding material from mainland Europe in planned progeny tests.

中文翻译：

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英格兰田间试验中美国梧桐（Acer pseudoplatanus L.）种源生长、形态和物候的轮作中期变化

1992 年，在“农场林地”地点建立了包含 8-10 个美国梧桐种子来源的田间试验，以确定在英国低地使用的最具生产力和适应性的种子来源。这些试验的早期结果发现，生长性状的来源之间几乎没有差异。为了指导不列颠群岛梧桐改良的下一步，重新审视了五个原始试验中的三个，并评估了 27 岁时生长和形态的变化，即三分之一到一半的轮换年龄。站点之间的增长存在很大差异，但出处之间的差异很小或不显着，并且站点之间没有相互作用。其中一项试验的春季物候评估表明，萌芽时间与纬度呈负相关，这是唯一提供任何种源间适应性分化证据的性状。然而，这种影响很小，并且是由于法国和德国种子来源的冲洗比英国种子来源晚得多。鉴于在不同地点缺乏明确的出处差异和质量相似的排名，我们发现现阶段没有理由将英国细分为梧桐的繁殖区，也没有理由在计划的后代测试中排除来自欧洲大陆的材料。