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代表美洲黑杨自然分布区大部份种源的内布拉斯加东部的7年生人工林中,美洲黑杨的生长、形态学和物侯学性状的变异,遵循着从西北到东南的渐变群的式样。由于美洲黑杨群落极大的异质性,对通过选种和育种来改良存在着极大的潜力。来自北纬33度以南的无性系,90%以上死亡或严重地遭受冬季的损伤。7个生长季节以后的最高树木是密苏里起源的。俄亥俄—宾夕法尼亚的树木在直径生长上居于首位。种源之间按总高度的排列在三个生长季节以后保持大体相同。家系和无性系的幼年期和7年生时高生长相关水平是好的(0.61到0.96),早期选择是可行的。粗糙而厚的树皮,长而大的分枝,大叶片和具有大量腺点,是俄亥俄—宾夕法尼亚、印第安娜的树木的特征。伊利诺斯南部、密西西比的许多无性系与俄亥俄—宾夕法尼亚和印第安娜的无性系是类似的。明尼苏达和威斯康星起源的树木,倾向于类似内布拉斯加、堪萨斯和南达科他的树木,具有光滑的树皮,小的侧枝以及小叶片,很少或没有腺点,并有很少锯齿。始出叶和开花期高度地相关。雄性无性系和雌性无性系的数量符和1∶1的性比率,而且没有由性别决定的差异。
Among the seven-year-old plantations in eastern Nebraska, which represent most of the provenance in the natural distribution area of Populus nigra, variations in the growth, morphology and phenology of Populus nigra follows a gradual change from northwest to southeast Swarm style. Due to the great heterogeneity of Populus deltoides communities in the Americas, there is great potential for improvement through selection and breeding. From clones south of 33 degrees north latitude, more than 90% died or seriously suffered winter damage. The tallest trees after seven growing seasons were of the origin of Missouri. Ohio-Pennsylvania trees top the diameter growth. The arrangement of provenances by total height remained generally the same after three growing seasons. Relatively high levels of growth in both pedigree and clonal juveniles and 7-year-olds were good (0.61 to 0.96) and early selection was feasible. Rough and thick bark, long and large branches, large leaves and a large number of glands, are characteristic of Ohio - Pennsylvania, Indiana trees. Many clones in southern Illinois and Mississippi are similar to the clones of Ohio-Pennsylvania and Indiana. Trees of Minnesota and Wisconsin origin tend to resemble trees in Nebraska, Kansas and South Dakota, with smooth bark, small lateral branches and small leaves, with little or no glandular dots and few jaggies. The starting leaf and flowering stage are highly correlated. The number of male and female clones is proportional to the sex ratio of 1: 1 and there are no gender-specific differences.