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Anatomical relations of root formation in strawberry
71-75.Views:156Anatomical relations of root formation are traced throughout the life cycle of the strawberry plant from the germinating seed up to the runners of the adult plant. Histological picture of the root changes a lot during the development of the plant. First the radicle of the germ grows to a main root, which makes branches into side roots and later adventitious roots are formed on the growing rootstock or rhizome. The anatomy of the different types of roots is also conspicuously different. First tiny branches appear relatively early after germination on the seedling's radicle, but soon the hypocotyl of the seedling thickens and develops side roots, which are already somewhat stronger. During this interval, the first true leaves are formed. The 4th or 5th of them being already tripartite, and the initiation of new roots extends into the epicotylar region of the shoot. The second years growth starts with the development of reproductive structures, inflorescences and runners starting from the axils of the new leaves. Near the tips of the runners below the small bunch of leaves, new root primordia are initiated. The tiny radicle of the germ develops a cortical region of 5-6 cell layers. Cells of the central cylinder are even smaller than the cortical parenchyma and include 3-4 xylem and 3-4 phloem elements as representatives of the conductive tissue. Roots originating from the shoot region are much more developed; their cortical zone contains 17-20 cell layers, whereas the central cylinder is about half as large. In the next year, new roots are formed at the base of the older leaves. These roots differ hardly from those of the last season in size and volume, however, they are recognised by colour and their position on the rhizome. The roots of the last year are dark, greyish-black, and grow on the lower third length of the rhizome, on the contrary, the new ones, on the upper region, are light brown. Roots starting from the shoot or rhizome are, independently from their age or sequence, mainly rather similar in size and diameter, thus being members of a homogenous root (homorhizous) system, i.e. without a main root. Plants developed and attained the reproductive phase develop in the axils of the leaves runners being plagiotropic, i.e. growing horizontally on the surface of the soil. The runners elongate intensely, become 150-200 mm, where some long internodes bear a bunch of small leaves and root primordia on short internodes and a growing tip. Runners do not stop growing, generally, further sections of 15-25 cm length are developed according to the same pattern, with small leaves on the tip. The growing tip of the runners is obliquely oriented, and small, conical root primordia are ready to start growing as soon as they touch the soil. The roots penetrate the soil, quickly, and pull, by contraction, the axis of the runner downwards, vertically, developing a new rhizome. The short internodes elongate a little and start developing adventitious roots. At the end of the growing season, the plantlets arisen on the rooted nods of runners are already similar to the original plants with homogenous root system. On the side of the adventitious roots, new branches (side-roots) are formed. The root-branches are thinner but their capillary zone is more developed being more active in uptake of water and nutrients. The usual thickening ensues later.
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Effects of activated charcoal on rooting of in vitro apple (Malus domestics Borkh.) shoots
98-101.Views:134Rooting of in vitro 'Royal Gala' shoots was studied under different conditions of root induction and root elongation phase. The rooting capacity was affected by both rooting phases. Very high rooting percentage could be reached with both liquid and solid root induction media. Raising the temperature from 22 °C to 26 °C during root induction phase increased the rooting percentage. Presence of activated charcoal in root elongation media can affect the number of roots per rooted shoots and can increase the rooting percentage, the length of roots and the rate of survival depending also on other conditions during rooting. Presence of NAA in root elongation media reduced the number and the length of roots considerably. Favourable effect of activated charcoal on rooting was mainly due to adsorption of NAA.
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Rhizogenesis in in vitro shoot cultures of passion fruit (Passiflora edulis f. flavicarpa Deg.) is affected by ethylene precursor and by inhibitors
47-54.Views:167The effects of the ethylene precursor ACC and two inhibitors, AgNO3 and AVG, on root formation were tested in in vitro shoots of passion fruit (Passiflora Midis f.flavicalpa Deg.). The organogenic response was assessed on the basis of percentage of shoot-forming. roots, root number and length. The time course of ethylene production was also monitored. ACC inhibited root formation by delaying root emergence and increasine, callus formation at the basis of the shoots. In addition, ACC caused a marked increase in ethylene production, coupled to leaf chlorosis and senescence with lower rooting frequencies, number and length of roots. IAA supplementation increased ethylene production. Both ethylene inhibitors, AgNO3 and AVG, at appropriate concentrations reduced callus formation at the basis of shoots. AVG increased the number of roots per shoot, but drastically reduced length of differentiated roots. Regarding to leaf pigments, ACC promoted a marked reduction on carotenoids and total chlorophyll, whereas AVG and AgNO3 delayed explant senescence and pigments degradation, not differing from IAA supplemented and non-supplemented control treatments. The results confirm previous reports on the beneficial effects of ethylene inhibitors on in vitro rooting and suggest its reliability to be used as an alternative approach to evaluate sensitivity of Passiflora species to ethylene.
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Stimulating effect of distilled water
47-49.Views:119It is an early observation that plants in poor soil are developing roots quicker and more abundantly than on rich one. There is a similar correlation between the nutrient status of medium and adventitious root formation.
In order to throw more light on the background of this strange phenomenon we started a systematic experimental program in which the biological effects of distilled water as model factor was investigated.
The experiments proved that the root formation of Pinto bean (Phaseolus vulgaris L.) cuttings with 3 cm long hypocotyls was promoted by distilled water.
The phenomenon above accompanied with slower decline and faster recovery of total and also water-soluble protein content, more intensive efflux of amino acids, greater amount of tryptophane and increased uptake of water compared to those in control hypocotyls. From other data obtained we may suspect that some additional active substance unknown for us also contributes to the stimulation of root initiation in distilled water.
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Effects of indole-3-butyric acid levels and activated charcoal on rooting of in vitro shoots of apple rootstocks
25-28.Views:249Rooting responses of rootstocks cvs. JTE-F1, M. 26 and MM. 106 were studied to different concentration of IBA in root induction media and to presence of activated charcoal in root elongation media. High rooting rate (>90%) could be achieved in cvs. JTE-H and M. 26, while cv. MM. 106 showed weak rooting ability at each IBA level tested. Increasing IBA content depressed the rooting only in cv. M. 26. Presence of activated charcoal decreased considerable the rooting rate in cv. M. 26 and decreased the number of roots in cvs. JTE-H and M. 26. These cultivars developed longer roots on media containing activated charcoal, while cv. MM. 106 did not showed any reaction for it.
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Organogenesis in eggplant (Solanum melongena L. cv. Embu) as affected by antibiotics and growth regulators
76-82.Views:213The influence of antibiotics (cefotaxime, timentin, kanamycin and hygromycin) and growth regulators (indolacetic acid and 6-benzylaminopurine) was evaluated on eggplant organogenesis. Solanum melongena hypocotyl segments (6 to 10 mm length), taken from 16 to 20-days in vitro grown seedlings, were used as explants. The basic medium was composed by MS salts, Gamborg vitamins and 2% sucrose, solidified with agar 0.8% and pH adjusted to 5.7±0.2. Morphogenesis was impaired at 50 to 100 mg L-I kanamycin and 7.5 mg L-1 hygromycin. Both Timentin and cefotaxime reduced the frequency of regenerating explants meanwhile hyperhydricity was not affected. A decrease in root regeneration was observed with increasing cefotaxime concentrations, although, timentin had no effect on root regeneration, as compared to the control treatment. Interestingly, the number of adventitious roots was more noticeable at 0.25 mg L-I IAA plus 0.5 mg L-1 BAP. However, if just IAA was added led to higher number of regenerated roots compared to other treatments.
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Post-effects of cytokinins and auxin levels of proliferation media on rooting ability of in vitro apple shoots (Malus domestica Borkh.) 'Red Fuji'
26-29.Views:206Rooting ability of in vitro apple shoots of 'Red Fuji' grown on proliferation media with different hormone content were tested at three IBA levels in root induction media. Rooting percentage could be slightly increased with an increase in IBA concentration in proliferation media. The highest IBA concentration (3.0 mg 1-1) in root induction media showed strong inhibitory effect on rooting capacity of in vitro shoots. The highest rooting percentage (95%) could be achieved by shoots grown on proliferation media containing TOP or BA+KIN as cytokinins before rooting.
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The effect of timing and IBA treatments on the rooting of plum rootstock hardwood cuttings
7-10.Views:214In propagation of plum by hardwood cuttings, the success of rooting is affected by several factors. Many authors deal with the timing of cutting collections, others investigate the optimal extent of hormonal stimulation. However, there is no data, as yet, about the coherence between these two factors. The aim of this experiment was to find the most advantageous condition s, with regards to both timing and IBA doses, for rentable propagation of the examined varieties. Five varieties were studied: 'INRA Marianna GF 8- 1', 'Myrobalan B', 'MY-KL-A', 'INRA Saint Julien GF 655/2' and 'Feher besztercei'. Cuttings were collected on seven occasions, during late autumn and winter, and were treated with IBA solutions of different concentrations. The optimal dose of IBA was found to be dependent both on the variety and the actual date of cutting collection . Results are reported, along with suggestions for optimal doses and collection periods.