摘要
本文对十个杨树种类（其中有无性系、变种、和种）一年生插条苗的叶、茎和根的生长及相互关系进行了研究，发现各种类生物量的高低与全株总叶面积的大小排列顺序大体相同。各种类叶面积的增长速率与高生长速率之间存在着正相关关系，绝大多数种类的相关系数在0．8－0．9左右，这表明未成熟叶片的光合产物是向上运输到顶端的，观察表明，速生种类叶片数目较少，而放叶间隔期较长，约1．7－2．2天，从生长较慢的种类为1．4－1．6天，对茎生长的研究中发现，生长期的长短不是造成高生长差异的主要原因，而速生期（即高生长速率达2．5cm/天以上）的长短及高生长速率最大值的高纸对茎生长的影响很大，最速生的品种72－170速生期长达99天，最大高生长速率达4．7cm/天，而生长差的种类小叶杨，小美12等，速生期仅17天，最大高生长速率分别为4．0cm/天和2．6cm／天。
This paper deals with leaf,stem and root growth of ten kinds (including clones,varieties and species) of one year poplar seedlings grown from cuttings.It is revealed that increases in biomass of these different kinds of poplar seedlings are arranged in an order corresponding to the order of increases in leaf areas.The correlation to the order of increases in leaf areas.The correlation coefficients between rate of leaf growth and height growth of these seedlings are all positive and most of them lie between 0.8-0.9.This suggests that photosynthates from immature leaves are transported mainly to the top of the seedlings.Fast growing seedings are shown to have fewer leaves but longer leaf plastochrons (about 1.7-2.2 days),and slow growing seedlings have shorter leaf plastochrons (only 1.4-1.6 days).From analysis of stem growth it is found that differences in height growth of the different kinds of seedlings are not due to duration of growing season,while duration of fast growing period (number of days with the height growth rate more than 2.5 cm/day),and the maximum height growth rate is the main factor to make the difference.For example,the fast growing clone '72-170' has a fast growing period of 99 days,and a maximum height growth rate of 4.7 cm/day.With some slow growing seedlings,such as Populus smonii Carr.,and P.simonii Carr.X pyramidalis-12,the fast growing period is only of 17,days,and with 4.0cm/day and 2.6cm/day as their maximum height growth rates respectively.
