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  • Author or Editor: R. M. Skirvin x
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Abstract

Rapid proliferation of axillary buds of ‘Thornless Boysenberry’ and ‘Thornless Young-berry’ (Rubus sp.) in tissue culture has been achieved on a modified Murashige and Skoog (MS) medium containing 6-benzylamino purine (BA) and α-napthaleneacetic acid (NAA). Shoots were induced to root on medium consisting of MS high mineral salts, myo-inositol, and thia-mine·HCl diluted to 1/16 to 1/2 strength and supplemented with full strength sucrose and agar. Rooted plants have been successfully moved to soil and grown in the greenhouse.

Open Access

To study the causes of low germinability in dried blackberry seeds, seeds harvested from fresh `Thornless Evergreen' (TE) blackberry (Rubus laciniatus Willd.) were either air-dried (12, 24, 36, 48, 60, 72, 96, or 120 hours) or explanted directly onto growth-regulator-free medium after bleach disinfestation. Seeds were either cut in half before explanting or kept intact. None of the intact seeds germinated. Fewer of the halved seeds dried 12 hours or more germinated than control (fresh moist) seeds (42.7% and 54.5%, respectively). Germination decreased to <12% following >48 hours of air-drying. In a separate study, fresh seeds of TE and `Navaho' were either dried as described or held in sealed petri dishes on moist filter paper (moist treatment) for up to 60 hours. After 60 hours, germination of dried seeds of both cultivars had decreased significantly; there was no significant change in germination percentage for moist seeds. Since moist halved seeds germinated well and dried halved seeds did not, the inability of dried blackberry seeds to germinate is due to more factors than just the hard seedcoat typical of the genus.

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A system to propagate tronchuda (Brassica oleracea var. tronchuda Bailey syn. costata L.) from main stem and side shoot cuttings was developed by removing the main stem (three to four leaves) and, later, side shoots from S-week-old plants, transplanting them into small pots, and growing them under a mist system for 4 weeks. New root growth appeared on cuttings within 3 weeks. Rooting frequency varied among cultivars and explant types. For all cultivars, side shoot cuttings rooted better than main stem cuttings (99.7% vs. 84.8%). For all cultivars, seed-propagated plants and side shoot cuttings produced leaves with significantly higher fresh weight than the main stem cuttings for three of the five cultivars. The average number of leaves per plant for four cultivars was, however, not significantly affected by propagation method. Average leaf count and fresh weight per plant were significantly higher for `Portuguesa' than for `Ana Maria'. `Couve Penca'. `Vilinda', and `Penca de Chaves' for all three propagation sources.

Free access

Abstract

Lam (1) has recently reported the production of embryoids from callused potato discs cultured in a modified Murashige and Skoog medium with the subsequent induction of shoots after the addition of 6-benzylaminopurine to the medium. While shoots readily proliferate in this medium, shoots are abnormal (Fig. 1). They have a reddish color and the slender stems have only rudimentary unexpanded leafy structures resembling bracts. Such abnormal shoots do not form roots, grow poorly, and do not survive when maintained continuously in the medium.

Open Access

`Embryonic axes-derived `Burpless Hybrid' cucumber (Cucumis sativus L.) plantlets germinated on Murashige and Skoog (MS) medium supplemented with 16 combinations of BAP and NAA and seedlings derived from whole seeds cultured on semi-solid agar were inoculated in vitro with two isolates (WFU3 and WFM13) of Pythium aphanidermatum. All axes-derived plantlets and whole seedlings inoculated with WFM13 isolates were susceptible to blight and died 2 days after inoculation. Similarly, all seedlings inoculated with WFU3 isolates were killed within 2 days after inoculation; however, the rate of development and severity of blight varied among the axes-derived plantlets. Blight on axes-derived plantlets, regenerated on MS medium supplemented with 2 mg BAP/liter and 0.2 mg NAA/liter, was significantly less than on regenerants cultured on all other amended MS media. On some media, callus developed on crowns and/or primary roots. The presence of callus influenced resistance to Pythium. In a second experiment, axes-derived cucumber regenerants from five genotypes, cultured on MS medium supplemented with 2 mg BAP/liter and 0.2 mg N&A/liter, were compared for their resistance to P. aphanidermatum isolate WFU3. Resistance was significantly greater for `Burpless Hybrid' and `Sweetslice' than for three other genotypes. Chemical names used: 6-benzylaminopurine (BAP); α -naphthaleneacetic acid (NAA).

Free access

Shoots of greenhouse-grown Algerian ivy (Hedera canariensis L.) were surface disinfected and explanted on modified Murashige and Skoog (MS) medium supplemented with BA (10 μm) and NAA (2.5 μm). One month later the shoots were transferred to MS proliferation medium supplemented with TDZ (0.1 or 0.5 μm) and NAA (40 μm). An average of three microshoots developed on each stem treated with TDZ. Pruned shoots grown on MS medium supplemented with GA3 (20 μm) and BA (20 μm) branched better than unpruned shoots (3.7 vs. 1 per explant, respectively). Rooted shoots grown ex vitro grew and developed a shape suitable for commercial sale in 3 months. Chemical names used: N -(phenyl-methyl)-l H -purine-6-amine (BA); gibberellic acid (GA3); 1-naphthaleneacetic acid (NM); N -phenyl-W-1,2,3-thiadiazo-5-yl urea (Thidiazuron, TDZ).

Free access

Abstract

The discrepancy in seed set observed in reciprocal crosses of red (Rubus idaeus L.) and black (R. occidentals L.) raspberries verifies unilateral incompatibility. The strength of the incompatibility varies between cultivars; some red × black crosses yield a small percentage of seed set by simple cross-pollination, while others produce almost no seed. Although black cultivars have shorter pistils than red cultivars, the role of this factor in incompatibility is unknown. Bud pollination and heat treatments increased seed set in some normally incompatible red × black crosses.

Open Access

Callus was initiated from leaves of Gladiolus cv. `Balady' on MS medium containing 1.0 mg/L NAA, 0.1 mg/L 2,4-D, and 0.5 mg/L kinetin. Organogenesis from callus was induced on medium containing 0.5, 1.0, 1.5, or 2.0 mg/L of either BA, kinetin, or TDZ. TDZ was more effective and resulted in a higher percentage regeneration and regenerant number. The microshoots produced were then propagated in vitro and cormel production was studied. Maximum shoot number (25.1) was obtained on medium containing 1.0 mg/L TDZ without auxin supplements in liquid shaking culture. In vitro cormel formation was significantly enhanced by B-9 and paclobutrazol. Increased sucrose concentration (4% to 5%) proved the most effective for cormel formation. Optimal dormancy break was obtained by storing cormels at 5°C for 1 month or by soaking them for 5 sec with 50 mg/L GA3. In-vitro rooting was achieved on solid medium containing NAA, IAA, or IBA, with higher root number recorded on NAA-treated cultures. Rooted microshoots were successfully acclimatized for ex vitro conditions and grown in the greenhouse. Plants produced from in-vitro propagation showed similar morphological characteristics of plants propagated by direct corm planting in the greenhouse.

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Abstract

Embryos extracted from developing apple fruit were cultured in vitro. Immature embryos (up to 4 weeks post anthesis), cultured without their testa and endosperm, produced only callus tissue. Six and a half-week-old embryos produced multiple shoots and the percentage of embryos producing shoots rather than callus tissue increased with time. Ten and a half-week-old embryos produced the highest number of shoots per embryo, after which a decrease in multiple shoot formation was observed with mature (14 weeks post anthesis) embryos producing 1 shoot and 1 root per embryo. Simultaneously, embryonic-axis free cotyledon cultures were established from embryos of various ages. Adventitious shoots developed from cotyledon explants, and the number of multiple shoots formed, increased with time (June-September). Cotyledons extracted periodically from mature fruit stored at 3°C continued to produce multiple shoots in culture, but this gradually decreased with time (15-120 days). After 6 months in cold storage, cotyledon explants failed to develop any shoots.

Open Access

Seeds of `Burpless Hybrid' cucumber (Cucumis sativus L.) were separated from their seedcoats and excised into pieces comprising an embryonic axis and two cotyledons. The seed pieces were disinfested and explanted on modified Murashige and Skoog medium with 16 combinations of BAP (2.0, 3.0, 4.0, 5.0 mg·liter-1) and NAA (0.0,0.1,0.2,0.3 mg·liter-1). On all media, embryonic axes germinated and grew into whole plants within 4 weeks, but did not flower. Cotyledons developed adventitious shoots and male flowers on most media. A few female flowers developed. The best shoot regeneration and the most female flowers were observed on medium with 2.0 mg BAP and 0.3 mg NAA/liter. One of the female flowers was pollinated in vitro and it developed a small fruit with viable seed.

Free access