Six cultivars of Achimenes, `Blau Import', `Blauer Planet', `Linda', `Prima Donna', `Schneewittchen', and `Tetraelfe', were grown for 16 weeks under short (SD, 8 hours) or long days (LD, 16 hours) at 21C in a greenhouse. LD increased plant height, shoot mass, number of flowers, and accelerated time to anthesis. SD, depending on the cultivar, increased number of rhizomes. Results show differences in several characteristics of growth and development among the cultivars and that LD promote shoot growth and flowering.
Three cultivars of Achimenes, `Flamenco', `Hilda', and `Rosenelfe', were grown for 10 weeks in nine environments: 17, 21, and 25C combined with 8, 16, or 24 hours of irradiance (213 μmol·s-1·m-2). Increase in temperature increased plant height, number of nodes, number of flowers, and shortened time to anthesis. Number of axillary shoots was enhanced at 17C. Increasing duration of illumination increased shoot dry weight and reduced plant height; a 16-hour light duration compared to 8 or 24 hours increased size and fresh and dry weight of rhizomes. `Rosenelfe' responded differently from `Flamenco' and `Hilda' to the environmental treatments. Depending on cultivar, top growth and flowering were influenced by temperature and duration of illumination, whereas rhizome growth was affected mainly by the latter.
J. C. Vlahos
Plants of Achimenes cv Hilda were treated with foliar sprays of Ancymidol, Paclobutrazol and Uniconazole at 3 different concentrations each, and were placed in a greenhouse at 21°C under 2 light levels (0 and 40% light exclusion) for 12 weeks. Reduced light level decreased plant height, number of axillary shoots and flowers. The three growth retardants in any concentration, supressed development of axillary shoots and flowers. Ancymidol at 25 and 50 mg.1-1, Uniconazole at 5 mg.1-1 and Paclobutrazol at 25, 50 or 100 mg.1-1 decreased plant height and number of leaf whorls. Number of rhizomes was reduced by the 3 chemicals at the highest concentration only. Paclobutrazol was most effective than the other 2 growth retardants. Effects of treatments were more pronounced under shade rather than in full sunlight. Days to anthesis was not affected by any of the treatments except by Paclobutrazol at 100 mg.1-1. The use of these growth retardants in concentration and mode of application similar to those used in this study is not recommended for “Hilda” as height retardation significantly reduces number of flowers
J.C. Vlahos and M. Dragassaki
Ebenus cretica, Leguminosae, is a characteristic endemic plant of the Mediterranean island of Crete. It is a perennial bush up to 1 m tall with composite pubescent leaves and pinky red or purple flowers on 5- to 20-cm-long racemes. The fruit is surrounded by the calyx and contains one seed. The plants grow on rocky hillsides in alkaline soils at an altitude of up to 600 m and flower from April to June. Ebenus has the potential for use as a container or landscape flowering plant, and this study was aimed at finding methods to propagate it either by seed or by shoot cuttings. Seed collected from native plants in late July/Aug. 1992 germinated well (70% to 90%) without scarification in a commercial potting mix. Fifty percent of the seed germinated in vitro between 13 and 25 days, depending on temperature and substrate used. Temperatures of 25 or 30C in light at a pH ≈6.0 favored germination. Removal of the dry calyx coating the seed enhanced germination and emergence. For rooting Ebenus cuttings, several concentrations of IAA, IBA, and NAA were used in combination with different types of cuttings (soft or hardwood, tip or basal, cultivated or wild). Best results were obtained by wounding the base and dipping shoot-tip cuttings (12 cm long) in 600 mg IBA/liter for 16 hours. Significant differences, however, were observed among germination and rooting percentages when seeds or cuttings were taken from different plants due to genetic diversity. Therefore, selection is required for optimal results.
J.C. Vlahos and M. Papadimitriou
Ebenus cretica, Leguminosae, is a perennial bush endemic to the island of Crete, and produces attractive pinky red or purple flowers on 15-cm long racemes. To study the possibility of its use as a cut flower, cut inflorescences on 40-cm-long spikes were taken from plants grown outdoors in the farm of the Technological Educati Institute and used to determine the postharvest characteristics of Ebenus flowers. Without any postharvest treatments, the inflorescences held in water had an average life of about 7 days. A solution of 100 ppm 8-hydroxyquinone sulfate (HQS) in DI water, supplemented with 5% Ca(NO)3 increased vase life for 2 days and improved the water potential without affecting transpiration, whereas the addition of 2% or 5% sucrose decreased vase life by 1 or 2 days respectively. Pulsing with 0.2 mm STS for 2 h improved flower quality and vase life. Addition of 6-BAP (2 ppm) or GA3 (3 ppm) in the preservative solution did not affect flower quality or vase life compared to control. These results indicate that inflorescences of Ebenus cretica may be used as cut flowers; however, further research is required to determine their sensitivity to ethylene as well as its storage capabilities.
J.C. Vlahos and P. Ververidis
Lupinus albus ssp. graecus, L. Fabaceae (Boiss. and Spruner) Franco and P.Silva, is being studied at the TEI of Heraklion since 1998 as a new plant with potential use in floriculture and ornamental horticulture. The plant has been recorded botanically; however, little is known about its physiology and genetic profile. Lupinus albus ssp. is a herbaceous annual plant 10 to 20 cm tall, growing at roadsides, field margins, vineyards, and olive groves up to 700 m altitude. The leaves are 5 to 11 cm wide, palmate shaped in alternate orientation, with five to nine leaflets 10 to 18 mm wide, all arising from the same point. The flowers are borne in terminal or lateral spike-like racemes 10 to 20 cm long. Florets are 15 mm long, dark blue occasionally with a white patch, stamens forming a tube. Pods are 60 to 70 mm long,with four to six black-spotted seeds. In the present work, seed germination studies were conducted combining chilling pretreatments with physical scarification (scratching). Mature seeds chilled at 5 °C for 6 weeks germinated readily (83%) when scarified with sand paper. Furthermore, we tested the effects of several plant growth regulators (chlorocholine chloride, paclobutrazol, maleic hydrazide and Ethrel 48) on young plants of Lupinus in order to obtain compact pot plants with more flowering racemes. Paclobutrazol at 5 and 10 mg/L achieved the best retardation effect, but did not affect flowering. In another trial with different potting media,the commercial potting soil proved the most suitable for growing lupins satisfactorily. It is concluded that Lupinus albus spp. graecus L. need further investigation in order to establish the best cultural conditions for its growth and development. Furthermore, due to its high genetic variability, selection and genetic improvement is required for optimal results.
J.C. Vlahos, M. Dragassaki, and I. Assargiotaki
Achimenes is a summer-flowering pot plant commonly propagated by shoot tip cuttings taken from rhizomes released from dormancy. Micropropagation was used in this study in order to establish a protocol for producing plants in winter when Achimenes are not usually available. Leaf segments, taken in August 1993, from hybrids `Flamenco', `Rosenelfe', `Bella', and `Sandra' grown in a greenhouse, were cultured on a modified Murashige and Skoog (MS) medium supplemented with 0.1 mg·liter–1 BA and 0.5 mg·liter–1; shoots proliferated without callus formation. Leaf explants taken from the proliferated shoots were placed on MS medium with 0.5 mg·liter–1 BA and 0.1 mg·liter–1 NAA for 8 weeks for further shoots proliferation. `Bella' showed vigorous growth and produced the most shoots (82) with no rhizomes, whereas `Flamenco' had the least shoots (28) along with rhizomes. Shoot tips were then transferred on MS medium supplemented with 0.5 mg·liter–1 NAA for 6 weeks where more vigorous shoots developed along with roots. Microcuttings were directly stuck ex vitro under moisture and rooted well in 4 weeks before planting in individual culture and flowered normally. These results provide the basis for a successful production of Achimenes hybrids for growth and flowering in winter months provided optimal temperature and irradiance levels are given.
J.C. Vlahos, G.F.P. Martakis, and E. Heuvelink
The effects of supplementary irradiance (20 μmol·s-1·m-2 for 6 hours) with incandescent light (I) or fluorescent compact gas-discharge lamps (CF) vs. a basic irradiance (96 μmol·s-1·m-2 for 12 h) with fluorescent (F) light at 17 or 25C was studied for Achimenes hybrids `Flamenco', `Hilda', and `Rosenelfe'. The additional I increased leaf area (LA) and plant dry weight (DW) in `Hilda' and `Rosenelfe' and promoted stem elongation in all three cultivars. Additional F had no effect on DW. However, depending on cultivar, responses for LA varied. An increase in the number of flowers was promoted only in `Rosenelfe' by I and CF compared with the control. In all cultivars, the supplementary CF, when compared with the I, reduced LA and DW. LA was significantly larger and DW higher at higher temperature, except for `Rosenelfe', where DW was not influenced and LA was smaller at the higher temperature. All three cultivars produced a longer stem and more flowers at the higher temperature. Calculated growth responses were influenced by an interaction between temperature and cultivar.
J.C. Vlahos, M. Dragassaki, A. Vasilaki, I. Assargiotaki, and A.M. Tsatsakis
Polymeric formulations of plant growth regulators (PGR) are high-molecular weight systems in which the PGR unit can be slowly released providing prolonged action and effectiveness in a wide range of concentrations. In this study, Achimene explants were used for testing the biological activity of polymeric derivatives of NAA and 2,4-D. Shoots of Achimenes `Bella', obtained from leaf segments cultured in vitro, were transferred for 8 weeks on Murashige and Skoog (MS) medium supplemented with different levels of conventional or polymeric NAA (0, 0.01, 0.05, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5 mg·liter–1) and 2.4-D (0, 0.01, 0.05, 0.1, 0.5, 1.0, 1.5 mg·liter–1), each combined with three levels of BAP (0, 0.1, 0.5 mg·liter–1). Compared to conventional NAA, twice as many shoots proliferated with higher dry weight, at 0.5 0.1, 1.0, or 1.5 mg·liter–1 polymeric NAA with 0.5 mg·liter–1 BAP. In another trial, the combination of 0.05 or 0.1 mg·liter–1 polymeric 2,4-D with 0.1 BAP gave more shoot and vigorous growth without callus formation, compared to conventional 2.4-D These results suggest that the polymeric derivatives of auxins used in this study enhance regeneration and growth of Achimenes in vitro more effectively than conventional formulations, at greater concentrations, without causing toxic or inhibitory effects.