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在对白榆研究的实践中发现,白榆生长快慢与叶片厚度有密切的相关性:即叶厚(外观上叶脉不明显,叶背较平滑)是白榆速生性的显著标志之一。经大量实测:厚叶榆的叶片厚度比对照厚26％,生长速度比对照快37％。据定株定期观察,幼苗一年生时叶厚,二年、三年生时叶仍厚;大树叶厚其无性系子代苗叶也厚。通过切片观察,叶片厚的榆树海绵组织占整个叶片厚度的1/4,对照为1/3;栅栏组织占整个叶片厚度的1/2,对照为4/9。叶片厚的榆树生长迅速的原因是:叶片海绵组织
In the study of Ulmus pumila, it was found that the growth speed of Ulmus pumila was closely related to the leaf thickness: that is, leaf thickness (the veins of appearance is not obvious, and the leaf back is smooth) is one of the significant signs of the rapid growth of Ulmus pumila. After a large number of measured: the thickness of leaves of Ulmus pumila was 26% thicker than the control, the growth rate was 37% faster than the control. According to regular observation of fixed plants, the annual seedling leaf thick, two years, three years when the leaves are still thick; large leaves thick clonal seedlings also thick leaves. By slicing observation, the thickness of the elm sponge tissue leaves accounted for 1/4 of the thickness of the entire leaf, the control is 1/3; palisade tissue thickness of the entire leaf 1/2, the control was 4/9. The reason why elm thick leaves grow rapidly is: leaf sponge tissue