Many species from economically important genera remain rooting recalcitrant, prohibiting the commercialisation of many species in forestry and horticulture, and hindering genetic improvement by conventional breeding or recombinant DNA technology, where vegetative propagation is often used to preserve the genetic fidelity of elite progeny. Two cherry species (Prunus avium and P. padus) were used as models in this study to investigate the physiological and genetic manipulation of adventitious rooting. Mature trees are typically more difficult to propagate vegetatively than their juvenile counterparts. For some trees, micropropagation can circumvent certain effects of ageing and maturation, restoring shoot vigour and rooting, but the mechanism(s) involved have not been elucidated. During micropropagation, subculture interval was found not to be the predominant factor promoting the 'apparent rejuvenation' of mature P. avium tissue. 'Apparently rejuvenated' ex vitro and hedged (putatively) mature P. avium trees were treated with gibberellins predicted to have a range of structural related activities. GA, improved the rooting of cuttings from hedged (putatively) mature cherry, but not from ex vitro trees. Methodology to regenerate adventitious shoots from P. avium leaf explants was developed, (putative) transgenic P. padus plants were produced by an Agrobacterium tumefaciens mediated strategy. Auxin redistribution in planta is postulated to require a component of active transport; inhibition of the predominantly basipetal transport has profound effects on rooting. The putative function of the Arabidopsis thaliana AtAUX1 gene is that of a cellular auxin influx carrier, possibly, as described by the chemiosmotic hypothesis. This thesis examined the hypothesis that transformation with the AtAUX1 gene would enhance the delivery of the root-inducing signal to improve rooting of P. padus, a species which is rooting recalcitrant and more or less obligate on exogenous auxin for this process. However, all six, constitutively expressed, Cauliflower Mosaic Virus 35S promoter driven, 35S::AtAUX1, transgenic shoot lines had reduced rooting.

No description available.

Palyginti išauginamų sėjinukų ir sodinukų aukščio nuokrypį, lyginant su standartu; įvertinti želdinių augimą priklausomai nuo taikomų technologijų; išanalizuoti lapuočių medžių dauginimo patirtį Vainagių medelyne. / To compare the growth of different kinds of plants for sowing and planting; to evaluate plants growth depending on the technology; to analyze the experience of hardwood trees propagation in Vainagių nursery.

Propagating methods for peach (Prumis persica L. Batsch.) are currently limited to the use of seeds or cuttings. Most of the rootstocks commonly used for establishing peach trees commercially originate from a narrow genetic base. The most commonly used peach rootstock in South Africa is 'Kakamas', which has disadvantages such as slow growth, and a high susceptibility to certain pests and diseases. 'Kakamas' is classified as a mid to late ripening cultivar, hence, its use as a rootstock is restricted in early ripening cultivars. Optimising peach seedling and cutting production may on the other hand increase more selection material that will increase genetic variability and also serve as the basis for future production and selection of rootstocks for peach nursery establishments. Hence, this study was designed to improves success of peach cutting production by increasing the rooting percentage and the survival rate of cuttings. This was firstly achieved by the application of various concentrations of IBA and several rooting-cofactors. Secondly, rooting success of cuttings taken at different seasons was studied. The response of two cutting positions to various IBA and rooting-cofactor was evaluated. Attempts were also made to overcome the requirement of peaches for a seed stratification period by using plant growth regulators. Studies to optimise the establishment and growth of embryos of early to late ripening cultivars ('Klara', 'Oom Sarel' and' Summer Giant') in vitro were undertaken to overcome the problem of small underdeveloped embryos which are often obtained from early ripening peach cultivars. The early ripening peach cultivars 'DeWet', 'Earlibelle' and 'Florida Prince' were propagated by softwood, semi-hardwood and hardwood cuttings prepared from August 1999 to July 2000. It was found that softwood cuttings prepared in October and November responded well to an IBA application of 1000 mg 1(-1), resulting in 100 % rooting in all three cultivars. In 'Florida Prince' and 'DeWet' the rooting-cofactors chlorogenic acid and phloroglucinol at the concentration of 100ug 1(-1) yielded 77 % and 81 % rooting, respectively while quercitin and rutinin gave only 46 and 44 % rooting for all cultivars. The basal portion of the cutting rooted better than the terminal portion (78 % versus 58 %). Rooting percentage differed in all treatments in response to IBA application and rooting-cofactors 74 % for 'Florida Prince', 62 % for 'DeWet' and 54 % for 'Earlibelle'. The use of IBA and Ca-EDTA proved to be beneficial for rooting of 'Florida Prince' cuttings and resulted in a rooting percentage of 86 % in wounded hardwood cuttings of this cultivar. It was also shown that the simple sugars glucose, fructose and sucrose as well as the sugar alcohols sorbitol and mannitol accumulated at the base of the cutting during adventitious base root formation if the cutting bases were treated with 1000 mg 1(-1) IBA. The concentration of these sugars and sugar alcohols were lower in untreated cuttings compared to IBA treated cuttings during the adventitious root formation process. Studies on the origin of adventitious root formation in stem cuttings of peaches were conducted using light microscopy and transmission electron microscopy. These studies revealed that adventitious roots originate (in peaches) in the vicinity of the vascular bundle tissue and in the cells around them. It was found, however, that adventitious root formation in IBA treated cuttings is associated with the formation of root primordia. These may trigger root initiation and ultimately the development of adventitious roots. In embryo culture studies the highest number of roots and greatest length of roots per embryo as well as the highest number of embryos forming roots was achieved when either the medium of Murashige and Skoog (MS) (1962) or of Steward and Hsu (SH) (1978) were employed. The Woody Plant medium (Lloyd and McCowan, 1978) and the medium after Schenk and Hildebrandt (1972) were found to be less effective when compared to MS and SH media. Addition of GA(3) (0.01 mg 1(-1)), BAP (0.2 mg 1(-1)) or GA(3) (0.01 mg 1(-1))+ BAP (0.2 mg 1(-1))+IBA (0.5 mg 1(-1)) to the media gave the best results with respect to embryos forming roots (86 %), number of roots per embryo (8.0) and total length of roots per embryo (7.57 cm). Furthermore, the following conditions for optimal rooting of peach embryos were established: pH 5.2, 1.5 g 1(-1) agar, 60 g 1(-1) sucrose and 16h light/8h darkness photo period. Further studies on the influence of the stratification temperature on germination of embryos revealed the highest germination percentage after exposure to 40 C ±2 constantly for 30 to 60 days. However, this chilling requirement can be successfully substituted by the addition of GA(3) , kinetin, zeatin, BA and thiourea to the culture media. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

High output commercial nurseries that cater for the forestry industry are continuously challenged to efficiently and cost effectively produce good quality planting stock to establish large plantations. Currently, South African commercial nurseries produce planting stock in solid compartmentalized trays. One of the major drawbacks of these containers is the susceptibility of trees to root deformation following outplanting, combined with the need for the return of empty containers to the nursery. A potential solution to these challenges is the introduction of wall-less plugs for the production of planting stock. Wall-less plugs are volumes of growing medium, usually cylindrical in shape, devoid of an impenetrable wall in which a plant can grow and establish itself. Such plugs may enable the production of planting stock with improved root systems, without the need for the return of empty containers after outplanting. In this research four prototypes of wall-less plugs were developed, produced on a small scale and tested. These were: 1) Paper-maché plugs made using the original WRIBLOK protocol whereby composted pine bark was bound together with repulped newspaper, 2) Sponge blocks, 3) Hessian bags and 4) Covetan bags. The performance of these prototype wall-less plugs was compared with the performance of four tray types used commercially by the forestry industry: 1) Poly 128 shallow, 2) Poly 98 deep, 3) Unigro 128 and 4) Sappi 49. These are polystyrene and polypropylene-based containers. Of these containers the Unigro 128 and Sappi 49 containers were of similar performance. Performance in terms of height and root collar diameter increase over ten weeks from the time of sowing of the paper-maché plugs was similar to that of the Unigro and Sappi 49 containers. The sponge block, Hessian bags and Covetan bags produced inferior quality planting stock compared to the other treatments tested. Although little progress was made in the ability to describe how one root system differs from another in terms of their branching patterns, a technique was developed to determine root surface area by image analysis software that is freely available. This method may prove useful for further research and for determining seedling quality in commercial nurseries. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.