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Effects of different cytokinins on the shoot regeneration from apple leaves of 'Royal Gala' and 'M.26'
69-75.Views:198The effects of different types of cytokinins on the shoot regeneration from leaf explants of apple scion 'Royal Gala' and apple rootstock 'M.26' were evaluated. Regeneration media contained either thidiazuron, or 6-benzylaminopurine, or meta-topolin, or zeatin, or kinetin, or their N9-ribosides, respectively, in the concentration range 0.5 to 8.0 mg 1-1. Effects of 'these cytokinins were evaluated on the percentage of regeneration (R%) and that of vitrification (V%) and on the number of regenerated shoots per explant (SN). Organogenetic index (0I) calculated from these data was used for the evaluation of efficacy of cytokinins. The course of shoot organogenesis also was followed using stereomicroscope. Types and concentrations of cytokinins applied in the regeneration media influenced each parameter significantly and the regeneration answer was strongly genotype-dependent. The best regeneration (SN: 11.08, 01: 7.5) was achieved in `Royal Gala' by using TDZ in concentration of 0.5 mg 1-1 (2.271,1M). There was a clear relationship between the effect on the regeneration efficacy and the chemical structure of cytokinins considering classical cytokinins, namely N9-ribosides applied in less concentration than nonribosides have the same or best regeneration effects except for 6-benzylaminopurine riboside. However, similar relationship could not be detected in the case of 'M.26'. SN was the highest (3.22) using 6.5 mg 1-1 (18.2011M) 6-benzylaminopurine riboside or 8.0 mg 1-1 (21.44 µM) meta-topolin riboside (3.18). SN was not significantly lower (3.12) by using 2.0 mg 1-1 (9.08 1M) TDZ, however, OI was about half as big (0.63 compared to 1.29 or 1.74 with 6-benzylaminopurine riboside or meta-topolin riboside, respectively). 'Royal Gala' had higher organogenetic ability, than `M.26': 3.5-fold higher shoot number per explant and more than 4-fold higher organogenetic index was reached with this cultivar than with 'M.26'. Moreover, the similar developmental stage of shoots could be observed 3-5 days earlier than in 'M.26' and if explants of 'Royal Gala' were further cultured with 3 weeks, SN increased from 11.08 to 24.42 on TDZ-containing regeneration medium, which might suggest higher organogenetic ability, too.
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A study of processes active in regeneration of different sweet cherry varieties
55-57.Views:207Cherries belong to the group of fruit trees, which require little attention in pruning. The process of getting bald branches is less accentuated, which is associated with the light requirement of organs changing along with the aging process. The growing habits of the varieties (length and number of growing shoots, etc.) is closely related with the productivity of fruiting parts. The ability of regeneration and the functional effectiveness of fruiting structures are expressed by the distribution according to their age. The differences registered justify the necessity to develop pruning policies for each particular type of variety. For that purpose, we have to examine the age dependency of the processes related to regeneration, which may serve as starting point of a pruning strategy. Growth of some parts should be stimulated in order to develop or regenerate fruiting parts. Some branches need to be rejuvenated, partially, as an antidote to progressive senescence. Every intervention is aimed to strengthen the development of the most productive constructions. Reactions induced by rejuvenation should be expressed in fruiting intensity. A pruning program adapted to the particular variety as well as to the actual phase of a rotating pruning system should anticipate results.
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Comparative study of the vegetative and generative organs in pear varieties
21-25.Views:117An assortment of 17 pear varieties was examined in 2006 at Keszthely, Department of Horticulture, Georgicon Faculty of Agriculture, Veszprem University. The selected varieties were planted in 1980, grafted on seedling rootstock and represented the majority of existing pear plantations in Hungary. The main objective was the determination of suitability of the most important varieties for the purpose of intensive growing technologies even when grafted on vigorous seedling rootstock. The most important growing and fruiting characteristics of the varieties have been assessed and evaluated from the point of view of productivity. We stated that the relations of the trunk or the main axis to the lateral branches and fruiting structures are all subject to varietal effects and are valuable indices of the growing character. The quotient of the diameters of trunk and branch should be around 0.3-0.4, and the relative frequency of fruiting structures (Dárda, nyárs, vessző) meaning the ability of branching and regeneration associated with accurate pruning policies are decisive from the point of view of promising success.
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Preliminary results of renewal pruning an 18 years old sour cherry trees
41-42.Views:168Sour cherry is a light demanding fruit species. As most of the crop is developing from buds on one year old shoots and 2-yearold wood, the formation of bare wood can be seen apparently in a badly maintained canopy. The formation of „whip shoots” indicates the degree of bare wood. Unfortunately in many gardens and commercial orchards sour cherry trees resemble willow trees. Owners often decide to grub old orchards, although the useful cropping lifespan of the trees planted in a correct spacing can be 20-30 years on a move vigorous rootstock. Therefore renewal pruning can contribute to the full renewal of the orchard, but the length of its effect is depending on the growth characteristics and renewal capabilities of the cultivar. The growth characteristics of the cultivars are different. The regeneration capabilities of different aged wood are also different. These differences emphasize the need for cultivar specifi c pruning. Knowing the reactions to renewal pruning, we can ensure regular high crops with excellent quality by applying cultivar specifi c rotation pruning.