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Walter J. Kender and Stephen Carpenter

Abstract

Orchard and greenhouse experiments were conducted to determine the influence of foliar applications of 6-benzylamino purine (BA) on branching of young apple trees. BA at 100 and 500 ppm, applied to actively growing shoots stimulated lateral bud growth on these shoots during the current season. The presence of fruit, termination of shoot growth, and the localization and non-persistence of BA reduced its effectiveness in breaking apical dominance. For optimum response to BA, multiple spray applications to actively growing shoots in a non-fruiting condition were required. Spray applications of BA failed to induce lateral bud growth on previous season’s wood.

Open access

E. D. Earle and R. W. Langhans

Abstract

Shoot tips of carnations (Dianthus caryophyllus L. cv. CSU White Pikes Peak) formed multiple shoots on agar nutrient medium containing 0.5 mg/liter kinetin and 0.1 mg/liter α-napthaleneacetic acid. Tissue with shoots was transferred to liquid medium on a culture wheel rotating 1 rpm. Many axillary shoots formed and eventually separated from the parent shoot. Tissue could be subcultured into fresh medium, stored at 4.5°, or rooted, potted and grown to flowering. All 175 plants flowered had normal white flowers with characteristic red flecks, indicating that the chimeral arrangement of the petal tissues had not been disturbed by the culture procedure.

Free access

Jacob George, Harsh Pal Bais, G.A. Ravishankar, and P. Manilal

Response surface methodology was utilized in statistical optimization of three quality factors (the number of multiple shoots, shoot length, and number of leaves) pertaining to regeneration of plantlets from leaf calli of Decalepis hamiltonii Wight. & Arn. (swallow root). The variables evaluated were the levels of sucrose, BA, and NAA each at two different concentrations. Response surfaces for shoot length and multiple shoot number were useful in achieving optimal levels of media constituents and in understanding their interactions, but response surfaces for number of leaves were not. The data indicate that sucrose, BA, and NAA levels may be manipulated to increase or decrease quality factors chosen. This approach may be useful in developing a micropropagation protocol for D. hamiltonii. Chemical names used: benzyladenine (BA); napthaleneacetic acid (NAA).

Free access

J.D. Norton, G.E. Boyhan, and J.A. Pitts

The dwarfing characteristics of St. Julien and Pixy rootstocks as measured by shoot growth and trunk cross-sectional area (TCSA) was evident. Tree survival was significantly reduced after 3 years on Nemaguard and Pixy rootstocks. None of the elements measured by foliar nutrient analysis were below the minimum for plums; however, significant multiple regression equations for total shoot growth, TCSA, and survivability were evident with R 2 of ≈0.30 in all three cases.

Open access

Dennis P. Stimart and James F. Harbage

Abstract

Stem pieces from expanding spikes of Liatris spicata (L.) Willd. were cultured in vitro on a Murashige and Skoog medium containing BA to establish proliferating cultures for use in comparing BA and IBA effects on shoot proliferation. Both compounds promoted multiple shoot development. The optimum level for micropropagation was 2.7 μm BA without IBA. Greatest rooting was at 5.0 μm IBA without BA.

Open access

John A. Driver and Andrew H. Kuniyuki

Abstract

Apical and lateral meristems of Paradox walnut (Juglans hindsii x J. regia) were used to investigate the possibility of accomplishing in vitro propagation of Paradox rootstock. A walnut specific medium, DKW, has been defined supporting optimum multiple shoot development under 4.5 μm benzyladenine (BA) and 5 nm indolebutyric acid (IBA) treatment. The method of analysis to determine the optimum level of constituents in tissue culture medium is discussed. Also reported is the in vivo rooting of tissue culture derived shoots.

Free access

Handan Büyükdemirci and Paul E. Read

Axillary buds of `Valiant' grapevine (Vitis spp.) grown in vitro were transferred onto Murashige and Skoog (MS) medium supplemented with different cytokinin and auxin combinations and concentrations. It was found that culture medium caused statistically important differences in number of nodes, number of fully expanded leaves, number of multiple shoots, number of roots, and length of shoots. MS medium supplemented with 1.0 mg BA/liter in combination with 0.01 mg NAA/L was found to be the best medium for shoot growth and callus production. MS medium supplemented with the combination of 0.5 mg BA/L and 0.01 mg NAA/L was the best medium for explant rooting. The medium containing BA and NAA encouraged better shoot growth than those containing BA alone. When the concentration of BA in the medium was increased, multiple shoot proliferation and teratological structures of explants increased, but the number of small leaves and length of internode decreased. Axillary bud culture led to better shoot growth than was found for shoot apex culture. The presence of leaves positively affected shoot growth from axillary buds. Also placing the axillary buds horizontally onto the medium gave better shoot proliferation and growth than placing them vertically.

Free access

Yasseen Mohamed-Yasseen

Neem is considered to be one of the most promising plants for producing pesticides, pharmaceutical, as well as many commonplace materials. A protocol for shoot formation from nodal and stem explants is described. Stem nodes and stem segments were obtained from mature tree and cultured in Murashige and Skoog medium (MS) supplemented with 0.5 μM thidiazuron (TDZ), and 0.5 uM naphthaleneacetic acid (NAA). Stem node explants produced multiple shoots which were separated and cultured on MS supplemented with 0.01, 0.03, 0.5, or 0.9 uM TDZ with 0.5 uM NAA. Stem explants produced callus which regenerated shoots upon transfer to a fresh medium. Formed shoots produced roots in proliferation medium or rooted in MS supplemented with 3.3 uN indolebutyric acid, and were transferred to soil. Number of produced shoots increased with increasing TDZ concentration but shoot and root length decreased.

Free access

Mohamed F. Mohamed, Paul E. Read, and Dermot P. Coyne

A new in vitro protocol was developed for multiple bud induction and plant regeneration from embryonic axis explants of four common bean (Phaseolus vulgaris L.) and two tepary bean (P. acutifolius A. Gray) lines. The explants were prepared from two embryo sizes, 3 to 4 mm and 5 to 7 mm, corresponding to pods collected after 15 and 25 days from flowering, respectively. The embryonic axis was cultured on Gamborg's B5 basal medium with 0, 5, 10, or 20 μm BA in combinations with 0, 1, or 2 μm NAA. The cultures were maintained at 24 to 25C under continuous light or incubated in darkness for 2 weeks followed by continuous light before transfer to the secondary B5 medium (0 or 2 μm BA or 2 μm BA plus 4 μm GA3). Adventitious roots or a single shoot with roots formed on the explants cultured on media without plant growth regulators. Multiple buds were induced on all BA media, but more were produced with 5 or 10 μm for most lines. Dark incubation greatly enhanced multiple bud initiation. Shoot buds were not produced on media containing NAA alone or in combinations with BA. On the secondary medium, six to eight shoots per explant for common bean and up to 20 shoots per explant from tepary bean were observed after 3 weeks. Mature, fertile plants were produced from these shoots. Chemical names used: benzyladenine (BA); 1-naphthaleneacetic acid (NAA); gibberellic acid (GA3).

Free access

Eric W. Mercure, Carol A. Auer, and Mark H. Brand

Tissue proliferation (TP) is characterized primarily by the formation of galls or tumors at the crown of container-grown rhododendrons propagated in vitro. However, TP of Rhododendron `Montego' is observed initially in in vitro shoot cultures and it is characterized by the formation of multiple shoots with small leaves and nodal tumors. The formation of shoots in `Montego' TP (TP+) shoot cultures occurs without the presence of exogenous cytokinin in the medium, unlike normal `Montego' (TP–) shoot cultures, which require cytokinin for shoot growth. Structural studies have shown that tumors are composed of many adventitious buds and parenchyma cells, suggesting that TP is a result of abnormal cytokinin regulation that is controlling tumor and shoot formation. Two approaches are being used to determine if differences in cytokinin concentration and/or metabolism exist between TP+ and TP– shoot cultures. In the first approach, shoot cultures are grown in vitro for 1 week in the presence of tritiated isopentenyladenine (iP). Cytokinin uptake and metabolism are analyzed using HPLC and other analytical methods. Experiments suggest that extensive degradation and N-glucoside conjugation occur in TP+ and TP– shoots, resulting in the removal of most of the exogenous iP. In the second approach, the levels of endogenous cytokinins such as iP, isopentenyladenosine, zeatin, and zeatin riboside, are being measured in TP+ tumors and shoots and in TP– shoots by an ELISA method.