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Cuttings of R. ponticum were treated or not with ‘Ukorzeniacz AB’ containing IBA and NAA, and placed in rooting medium (temp. 21°C). Transverse sections were made of the bases of the cuttings removed from the soil after 2; 3; 4; 5 and 6 weeks. Meaningful anatomical changes in anatomical structure of R. ponticum cuttings connected with wound-healing process could be seen during rooting. In first two weeks periderm in cortex and callus from cambium and phloem emerged as a response to wounding of cuttings. After 3 weeks initiation of wound xylem started in callus. It developed very intensively and did not depend on the way of cutting treatment. Application of auxins did not or not considerably influenced the anatomical changes in stem structure of R. Ponticum during rooting – proliferation of new xylem was similar in control cuttings and in cuttings treated with rooting stimulator ‘Ukorzeniacz AB’, although it stimulated initiation of root primordia. Adventitious root formation occurred only in cuttings treated with ‘Ukorzeniacz AB’, in which numerous root primordia could be observed after 3 and more weeks of rooting. In control cuttings there was none of them even after 6 weeks of rooting.
July and September. The most efficient regeneration and axillary multiplication were achieved on the medium supplemented with meta-topolin. The application of BAP caused a lower regeneration potency of explants and resulted in a decrease of shoot quality with every subculture. Four of the six cultivars showed growth inhibition after three months of growth on BAP-medium. The highest multiplication rate (2.7-4.7 depending on genotype) and the high quality of shoots were noted on the medium supplemented with mT (0.5-1.0 mg l-1). It is also very important to note that mT had stimulating effect on organogenesis in P. × hederaefolium and P. × hortorum cultivars over the long term. Moreover, meta-topolin had no after-effect on the growth and inhibition of rooting. Only one cultivar ("Sofie Cascade") rooted better on control medium without auxin. In case of the other cultivars, IBA added in concentrations of 0.01-0.1 mg l-1 had a stimulating effect on root production. The higher level of auxin inhibited root formation, stimulated senescence of shoots and had a negative after-effect on acclimatization in greenhouse conditions.
To study the relationship between glutathione and rooting, tomato seedling cuttings, grown on basal- or on auxin-supplemented media, were treated with the reduced (GSH) or oxidized (GSSG) form of this antioxidant. In turn, the consequences of the depletion of GSH pool on rooting were tested using L-buthionine sulfoximine (BSO), a specific inhibitor of GSH biosynthesis. Effects of the aforementioned treatments on rooting response were assessed. GSH treatment promoted root formation on cuttings grown on both basal- and auxin-supplemented media. Whereas GSSG did not affect the number of roots formed by cuttings grown on basal medium, it strongly enhanced the rooting stimulatory effect of auxin treatment. GSH depletion resulting from BSO application did not change the number of roots formed. All the tested compounds, namely GSH, GSSG, BSO and auxin, had a strong inhibitory effect on the elongation of regenerated roots. Supplementing the rooting medium with glutathione efficiently increased the GSH level in the rooting zones, while addition of BSO led to a strong decrease in endogenous GSH level. Neither of the treatments affected the level of GSSG. Exogenous auxin affect neither GSH nor GSSG levels in rooting zones; however, in the regenerated roots, GSH level was significantly higher when the organs were formed on auxin-supplemented medium. Patterns of GSH distribution in the roots regenerated on basal- and auxin-enriched media were studied using the GSH-specific dye monochlorobimane and confocal laser scanning microscopy. GSH was found in the root apical meristem and in the elongation zone. Auxin did not change the GSH distribution; however, the number of fluorescent cells was higher when roots were regenerated on auxin-supplemented medium.
On the basis of conducted experiments on the rooting of dawn redwood cuttings it was found that the application of Seradix B No 1 mixed with Kaptan Zawiesinowy 50 (1:1, v:v) increased the number of rooted cuttings by 14.5% in comparison to the control. Moreover, an advantageous effect of the growth stimulator was observed on the number of secondary roots on a cutting. However, the application of a growth promoter did not have a marked effect on their length. Incision wounding of cuttings at their base had an adverse effect on the rooting percentage and the length of secondary roots. It results from the conducted observations that at the position of the incision wounding roots are not formed. It can be seen from the performed cross-section that dawn redwood regenerates roots from the cambium (cambial ring) and not from the callus. For this reason the labour-intensive procedure of incision wounding of cuttings is not recommended in the propagation of dawn redwood. The effect of two factors, i.e. incision wounding of cuttings and the application of a growth regulator, on the rhizogenesis process in dawn redwood was investigated in this study.
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