A Simple in Vitro Method to Avoid the Initial Dark Period and to Increase Rooting in Fruit Trees

In vitro propagation of northern red oak (Quercus rubra) shoots was successful from cotyledonary node explants excised from 8-wk-old in vitro grown seedlings. Initially, four shoots per explant were obtained on Murashige and Skoog (MS) medium supplemented with 4.4 μM 6-benzylaminopurine (BA), 0.45 μM thidiazuron (TDZ), and 500 mg l −1 casein hydrolysate (CH) with a regeneration frequency of 64.7% after 3 wk. Subculturing explants (after harvesting shoots) to fresh treatment medium significantly increased shoot bud regeneration (16.6 buds per explant), but the buds failed to develop into shoots. A higher percentage (73.3%) of the explants regenerated four shoots per explant on woody plant medium (WPM) supplemented with 4.4 μM BA, 0.29 μM gibberellic acid (GA 3 ), and 500 mg l −1 CH after 3 wk. Explants subcultured to fresh treatment medium after harvesting shoots significantly increased shoot regeneration (16 shoots per explant). Shoot elongation was achieved (4 cm) when shoots were excised and cultured on WPM supplemented with 0.44 μM BA and 0.29 μM GA 3 . In vitro regenerated shoots were rooted on WPM supplemented with 4.9 μM indole-3-butyric acid. A higher percentage regeneration response and shoot numbers per explant were recorded on WPM supplemented with BA and GA 3 , than on MS medium containing BA and TDZ. Lower concentrations of BA and GA 3 were required for shoot elongation and prevention of shoot tip necrosis. Each cotyledonary node yielded approximately 20 shoots within 12 wk. Rooted plantlets were successfully acclimatized.

Section: Resultssupporting

confidence: 62%

In vitro propagation of northern red oak (Quercus rubra L.)

Vengadesan

Pijut

2009

“…While dark conditions enhanced the rooting frequency, at the same time, they adversely affected shoot Values followed by the same letters within the column are not significantly different at 5% level (Duncan's multiple range test) a Values are means±standard error quality, causing leaves to yellow and fall. Rugini et al (1988) had reported a similar decline in the quality of shoots and subsequent survival of plantlets on account of dark pretreatment. The inclusion of 0.46 μM Kin in the rooting medium improved the quality of the shoots only marginally.…”

Section: Resultsmentioning

confidence: 71%

In vitro propagation of a high value medicinal plant: Asparagus racemosus Willd.

Bopana

Saxena

2008

Asparagus racemosus Willd. is an important medicinal plant of tropical and subtropical India. Its medicinal usage has been reported in the Indian and British Pharmacopoeias and in traditional systems of medicine such as Ayurveda, Unani, and Siddha. The multiple uses of this species have increased its commercial demand, resulting in over-exploitation. Because of destructive harvesting, the natural population of A. racemosus is rapidly disappearing, and it is recognized as 'vulnerable' (Warner et al., Some important medicinal plants of the Western Ghats, India: a profile. International Development Research Centre, Artstock, New Delhi, India, 15 pp, 2001). The development of an efficient micropropagation protocol will play a significant role in meeting the requirements for commercial cultivation, thereby conserving the species in its natural habitat. In the present study, in vitro shoot proliferation was obtained by culturing single node segments in Murashige and Skoog's (MS) medium supplemented with 3.69 µM 2-isopentyl adenine and 3% sucrose with a multiplication rate of 3.5. For proper root formation, the in vitro-formed shoot clusters were cultured on half strength (major salts reduced to half) MS medium with 1.61 µM 1-naphthalene acetic acid, 0.46 µM kinetin, 98.91 µM adenine sulfate, 500 mg/l malt extract, 198.25 µM phloroglucinol, and 3% sucrose. On this medium, 85% rooting was observed within 20 d. Following a simple hardening procedure involving sequential transfer of plants to a greenhouse, polyhouse, and shade net, the tissue-cultured plants were transferred to the field where the survival rate was 100%.

“…In addition, a dark treatment of 3 d was found to be sufficient to induce rooting in both genotypes. It has also been reported that excluding light from the root zone by overlaying the media surface with black polycarbonate granules and painting the outside of the culture tube improves rooting in almond (Rugini et al, 1988(Rugini et al, , 1993. In this study, a similar environment was achieved by adding black food dye to media.…”

Section: Discussionmentioning

confidence: 78%

“…Although darkness during the first week of the rooting phase has been found to be essential in stimulating rooting in some woody species (Rugini et al, 1993), shoot etiolation can induce early senescence, causing shoot yellowing and a reduction in plantlet survival (Rugini et al, 1988). While prolonged periods of darkness (10 -14 d) have been used to promote root development in hard shell almonds (Rugini and Verma, 1983;Caboni and Damiano, 1994), preliminary experiments with 'Ne Plus Ultra' using similar regimes caused severe leaf yellowing (data not shown).…”

Section: Discussionmentioning

confidence: 99%

In vitro rooting of almond (Prunus dulcis Mill.)

Ainsley

Collins

Sedgley

2001

Shoot cultures of the paper shell almond (Prunus dulcis Mill.) cultivars 'Ne Plus Ultra' and 'Nonpareil' were subcultured for 4 wk at 48C on growth regulator-free basal medium under low light conditions. Elongated shoots were excised and their response to a range of rooting treatments determined. Various concentrations of indole-3-butyric acid (IBA) and anaphthaleneacetic acid were compared over a range of incubation periods to determine the optimum auxin for root formation. In addition, the effect of shoot base shading, phloroglucinol (PG), and basal salt composition were examined. The treatment resulting in the best rooting of both cultivars was shoot insertion for 12 h into water-agar (0.6% w/v) with 1.0 mM IBA, followed by 2 wk in basal medium without auxin but with 100.0 mM PG. Explants were maintained under dark conditions for 3 d at the start of the treatment period, then exposed to light. Extending the darkening period did not improve rooting ability. Whilst half-strength Murashige and Skoog basal medium was suitable for rooting 'Ne Plus Ultra' shoots, fullstrength Almehdi and Parfitt medium resulted in the best rooting of 'Nonpareil'. Under these conditions, 60.0% of explants developed adventitious roots.