Studies On Anatomical Characteristics Of Adventitious Root In Different Developing Phases Of Xanthoceras Sorborifolia Cutting

This research took half lignification softwood cuttings and one-year hardwood cuttings of Xanthoceras Sorborifolia for cutting propagation,then samples were collected regularly and the morphological changes of at the base of the cuttings were observed. We studied that effective accumulative temperature of inserting soil have impact on rooting process and IBA treatment have impact on rooting rate and root morphology indicators. The main findings are as fellows:(1) There is no Latent root primordium in Xanthoceras sorbifolia cutting before cuttage, and adventitious root developed from induced root primordium. Induction of root primordium arise from the parenchyma cells within the callus. Adventitious root formation of Xanthoceras sorbifolia cuttage is divided into three stages. The first stage, callus formation(0-15d). Outer skin near1-2cm incision began to divide, and some cells in phloem parenchyma firstly dedifferentiate and recovery the ability to divide, cell number and cell volume keep increasing and then form large number of parenchyma cell, the development of parenchyma cell form callus near cut. The second stage, some parenchyma cell within callus began to differentiate and formed root primordium and adventitious root formation (15～25d), On20th day of cuttings,parenchyma cells within callus began to differentiate, gradually develop into induced root primordium with obvious nucleus, concentrated cytoplasm, size uniformity. The third stage, adventitious root expression and elongation(25d-). Adventitious root primordia cells continue to divide.(2) When it obtained effective accumulated temperature, Xanthoceras sorbifolia complete morphology changes of their growth period.800mg/L IBA treatment, on15th day of cuttings, effective accumulated temperature reached185.96℃, cuttings base incision of Xanthoceras sorbifolia Bunge has formed a large amount of creamy callus; On20th day of cuttings, the effective temperature reached266.32℃, Xanthoceras sorbifolia has completed root primordium induction and adventitious root formation; cutting the25d, when the effective accumulated temperature reaches341.76℃, adventitious root of Xanthoceras sorbifolia Bunge cuttings come out from callus(3) Exogenous hormones IBA can significantly improve rooting rate and root morphological indices of Xanthoceras Sorborifolia hardwood cutting, best root and more than65%rooting rate of hardwood cuttings occurred at IBA concentration800mg/L. IBA reduced proportion of root morphological indices in small-diameter distribution, and improved the distribution ratio of large-diameter; there were significant correlations between the total root length and the total surface area, the total volume and IBA concentration, but correlation coefficient is different. Descending order are as follows:total root volume (r=.9678, p <0.01)> total root surface area (r=0.9665, p<0.05) root total root length (r=0.9627, p <0.05), the trend of regression curve is approximately the same. IBA concentration was maintained at795～820mg/L, Cuttings of Xanthoceras Sorborifolia can obtain higher root morphological indices.(4) Adventitious roots of Xanthoceras Sorborifolia softwood cuttings induced IBA treatment is better than the control treatment and ABT1treatment. Softwood cuttings rooting process are similar to hardwood cuttings. It can also be divided into three stages. The first stage, the callus formation, firstly slight expansion appeared at the base of1cm of the cuttings. With the increase of cutting days,slight expansion was more and more obvious until cracking, incision of the expansion gradually produce white callus;The second phase, root primordium induced and adventitious roots formation, the base expansion was extremely clear, adventitious roots stretched out from callus epidermis;The third stage, adventitious roots express and extend, a large number of adventitious roots stretched out from the cutting and further elongation.(5) Pathological examination confirmed the rotting of the base of the cuttings in the process of cutting propagation, pathogen is Fusarium. Xanthoceras Sorborifolia is susceptible to Fusarium species, Comprehensive measures should be taken on disease prevention, the nursery in the history of cruciferous crops in the land should be avoided;It should select a broad spectrum and absorption of the fungicide.Tebuconazole and carbendazim is the best selection. Seedbed, cuttings and surrounding environment should be sterilized regularly.