Anatomical Studies On Adventitious Root Development Of Tetraploid Robinia Pseudoacacia

The influence of insert soil temperature, cuttings processing measures, cutting season on rooting is the important content of research on rooting regulation mechanism of difficult to take root tree species cuttings. This research took tetraploid robinia of one-year shoots cuttings and one-year hard wood cuttings for materials, all optical spray and Yang Qi cutting seedlings were used respectively, then cuttings base samples were regularly collected and we made paraffin section. We observed the changes of anatomic features of cuttings rooting position, studied the effection of temperature on adventitious roots happening and rooting process of robinia tetraploid hard wood cuttings after IBA treatment and the effection of cottage season on the adventitious root happening of robinia tetraploid shoots cuttings. The main results are as follows:(1) In the Yang Qi of soil heating temperature at 26±0.5℃, the initial rooting rate (30d) and final rooting rate (50d) were significantly higher than YangQi without heating (P < 0.01). The soil temperature has a significant influence on the rooting of robinia tetraploid rooting cuttings and takes a vital place in the process of the generation of adventitious roots.(2) In the heating YangQi, the increase of soil effective accumulated temperature can significantly promote the advance of the callus induced period of hard wood cuttings, induced period of root original base and the expression and extention period of adventitious roots. Only in the case that the effective accumulated temperature was higher than 109.25℃,211.68℃å'Œ301.38℃, it can induce the occurring of callus of robinia tetraploid hard wood cuttings, root original base and the expression and extention of adventitious roots. The IBA treatment can just change the effect of rooting rate of cuttings, but it cannot promote the advance of the occurring time of every stage of the cutting rooting process.(3) In mid of May, the cuttings of all treatments started to root after 15 days, which was five days ahead of them in June and July. This indicates that cuttage season has an obvious effect on the rooting rate and rooting happening of robinia tetraploid cuttings.(4) The rooting rate of mid-may cuttings improved significantly and the rooting rate of the 35d control processing of the mid-may reached 56.66%. And those group that was added additional 1,400 mg/L IBA, the rooting rate of the mid-may group increased to 85.83 % and the mid-July ones was just 26.67 %. It indicated that there existed an extremely significant difference (P < 0.01) in the initial rooting rate (15d) and eventually rooting rate (40 d) in the mid-may group when compared with the mid-June and mid-July; the time of the cutting of robinia tetraploid played an critical role in the process of the being of adventitious roots. However, the existence of IBA only could change the result of rooting rate and was not capable of making the rooting time start in advance.(5) The root primordium of hard branch produced in the pith ray and cortex parenchyma cells, border callus and the ones not in the root of the cuttings YangQi gla produced only in original base on callus. In the aspect of anatomy of cuttings shoots, the original foundation of callus tissue produced in three different times .(6) The being of adventitious roots cuttings of tetraploid robinia shoots hard branch process can be divided into three stages. First, it was the being and growth of callus formation. In the stage, the original callus was a group of parenchyma cells, which were big, suborbicular and arranged loosely and the nucleus of the cells were not obvious too. Second, the root primitive body and original base rooting started to differentiate. The number of callus increased while their internal some cells also began to differentiate. When the cell wall was thicken ,some cells started to differentiate into root primitive cells, other cells specialized into cells that have the character of primitive root body cells. There is an obvious bound between them and the surrounding callus parenchyma cells and this group of cells generated into conducting tissue catheter tube cells, which can form their own procambium, nearly the group of cells, root tip also was aslo induced. At last, adventitious roots being and growth, the adventitious roots generated after cutting can extend.