不同切根处理对林木幼苗根系侧根生长的影响

Effects of different root-cutting treatments on seedling lateral root development

在基质栽培和营养液栽培条件下，对侧柏、刺槐和白榆幼苗主根分别进行切除1／3，1／2和不切除试验，以研究不同切根比例对一级侧根数量、一级侧根总长度以及一级侧根发生位置的影响．结果表明，对苗木进行主根切断，抑制了主根的生长，促进了一级侧根的发生，使切根处理后的幼苗在一级侧根的数量和总长度上均大于全根苗．一级侧根发生的数量以及生长量与主根切断比例有关，1／3切根的增加幅度大于1／2切根处理，说明一级侧根的发生随着主根伤害程度的增加而有所减小．一级侧根的发生位置比全根苗更接近于根基．3树种全根苗一级侧根的发生位置主要集中分布在2～5cm，而1／3切根苗的一级侧根主要分布在2～4cm，1／2切根苗的一级侧根主要分布在2～3cm．

Under the substrate culture and solution culture conditions, taproots of Platycladus orientalis, Robinia pseudoacacia and Ulmus pumila were cut off 1/3 and 1/2, the lateral root number, lateral root total length and the emerging position of seedlings with different root-cutting ratio were investigated compared to controls with intact roots. The results showed that root-cutting prohibited taproot growth, promoted lateral root development, and consequently, seedlings after root-cutting had a greater lateral root number and total length than the controls. The degree of lateral root development had a significant relationship with root-cutting ratio, and 1/3 root-cutting developed more lateral roots than 1/2 root- cutting, indicating that the stimulative effect of root-cutting is diminished with the increasing of root- cutting ratio. The lateral root of root-cut seedlings emerged closer to rootneck than the controls. The lateral root emerging position of seedling with intact roots distributed maily in 2- 5 cm, and in contrast, 1/3 root-cutting in 2 -4 cm and 1/2 root-cutting in 2 -3 cm.