杨树无性系根系特征及地上与地下部分相关性研究

采用大田挖掘法，对20个杨树无性系的根系特征及地上与地下部分的相关关系进行了研究。结果表明，20个杨树无性系的根系主要集中在0～50cm土层中，根系以水平根为主，垂直根基本消失，不定根与地面的夹角较小，基本保持水平。中驻1号、NL351、T26和中驻6号的不定根总长度较大，中驻1号、中驻6号、W07和1107的不定根总数量较多，基部直径在2cm以下的不定根占不定根总数量的60％～80％。从地上和地下部分的生长情况来看，树高、冠幅、地上部干重、根重和根长存在显著相关关系；20个杨树无性系的根冠比在0．23～0．45的范围之内；单位地上部所具有的根长差异性较大，最大的为T26，最小的为中菏1号；根系生理吸收效率与根冠比、单位地上部所具有的根长呈负相关关系，即根系冗余现象。通过聚类分析，在相似系数为1．3时，可将20个杨树无性系分为3类6个亚类。研究结果可为杨树优良无性系的进一步选育和抚育管理提供理论依据。

Studies on roots characteristics and correlations between the aerial and underground parts of Populus clones

A field experiment was conducted to investigate the roots characteristics and the correlations between the aboveground and underground parts of 20 Populus clones. The results showed that their root systems are mainly concen- trated in 0 - 50 cm soil layer, the root system is given priority to with horizontal root, vertical root basic disappearance, adventitious roots of small Angle, with the ground close to the level. Zhongzhu-1, NL-351, T-26 and zhongzhu-6 had larger total length of adventitious roots and zhongzhu-1, zhongzhu-6, NL-351 and 1-107 adventitious roots in the total quantity is more which the ground diameter under 2 cm accounted for 60% - 80% of total number of adventitious roots. The growth indexes between the aerial and underground parts, exists significant correlation relationship, such as height, crown diameter, root weight and root length. The root/shoot ratio ranged from 0. 23 to 0. 45. The root length per unit shoot weight differences is bigger, the biggest for T26, the smallest for zhonghe-1. The root absorption efficiency was significantly negative correlated with the root/shoot ratio and the root length per unit shoot weigh, known as root redun- dancy. By cluster analysis, 20 Populus clones were divided into 3 groups and 6 categories at similarity coefficient 1.3. The results may provide a theoretical basis for further breeding improved clones of poplar and management.