Slow post-hydration drying improves initial quality but reduces longevity of primed bitter gourd seeds

Many environmental factors are known to affect the success of priming, post-hydration drying being critical. Accumulated evidence shows that priming improves the quality of bitter gourd (Momordica charantia L.) seeds. However, the effect of post-hydration drying on the their longevity remains unclear. This study evaluated the effects of post-hydration drying speed on the emergence performance and anti-oxidative activities of primed bitter gourd seeds stored for 48 weeks. Results indicated that priming improved emergence percentage, mean emergence time and seedling growth of treated seeds. Primed seeds also showed lower peroxidation, as indicated by the accumulation of malondialdehyde (MDA) and total peroxide, and higher total anti-oxidative activities (TAA) than non-primed seeds. The seeds receiving slow post-hydration drying treatment exhibited faster emergence and better seedling growth than the seeds receiving fast post-hydration drying treatment and the non-primed control. However, the longevity of slow-dried seeds decreased considerably during 48 weeks of storage as compared to that of non-primed and fast-dried seeds. Fast drying treatment maintained the longevity of primed seeds for up to 24 weeks as compared with non-primed control or slow-drying seeds. Improved longevity was due in part to enhanced TAA that minimized the accumulation of MDA and total peroxide during storage.     

The effects of NaCl pre-treatments on salt tolerance of melons grown under long-term salinity

The response of melon (Cucumis melo) plants to long-term salinity was investigated to determine the availability of the NaCl pre-treatments (seed priming + seedling conditioning) as an interesting strategy for increasing the salt tolerance. Seeds of melon cultivars “Hasanbey” and “Kirkagac” were primed with 18 dS m⁻¹ NaCl solution for 3 days at 20 °C. During emergence and seedling growth, non-primed seeds were irrigated with local irrigation water (EC: 0.3 dS m⁻¹) whereas primed groups were treated with 9.0 dS m⁻¹ saline solution for 35 days. Seedlings derived from pre-treated (P) and non-pre-treated (NP) groups were transplanted to 8 l pots. After transplanting, salinity treatments were started with the first irrigation. The salinity treatments consisted of five levels (control, 4.5, 9.0, 13.5 and 18.0 dS m⁻¹) of irrigation solution for a period of 90 days. NaCl pre-treatments diminished the inhibiting effect of salinity on growth of melon plants. However, competence for salt adaptation varied with cultivar and the level of salinity. The physiological response of the P plants was also maintained in the long-term. Stomatal conductance and relative chlorophyll content of P plants tended to be higher than those of the NP ones. In addition, NaCl pre-treatments enhanced K and Ca concentrations of leaves and stems, and prevented toxic effects of salinity because less Na accumulated in stems. These results suggest that the use of NaCl pre-treatments could be a useful strategy to increase the salt tolerance of melon plants in the long-term and also to permit the establishment of melon crop by direct sowing in a saline medium.     

Fruit set,seed development and embryo germination in interploid crosses of citrus

Interploid crosses of diploid Kinnow mandarin, Succari sweet orange and Sweet lime with tetraploid Kinnow were made reciprocally for the production of triploid plants. Low fruit set and occurrence of underdeveloped or empty seeds was common in all interploid crosses. The hybrid fruits harvested after 12–14 weeks or 7 months after pollination produced many underdeveloped and few developed seeds; however, tetraploid Kinnow as seed parent yielded more developed seeds per fruit. The under developed seeds were devoid of endosperm. Nucellar embryony was higher in the diploid than in the tetraploid strain of Kinnow. Immature embryos of seeds harvested 12–14 weeks after pollination were cultured in vitro on MS media supplemented with adenine sulphate (20 mg l⁻¹) and malt extract (500 mg l⁻¹). Maximum germination (75%) of hybrid embryos from underdeveloped seeds was obtained in 4× × 2× cross of Kinnow strains. The germinated plantlets were transferred into pots and noted 59–89.3% survival rate in various crosses.     

Both anti-oxidation and lipid-carbohydrate conversion enhancements are involved in priming-improved emergence of Echinacea purpurea seeds that differ in size

This study evaluated the effects of priming on emergence responses of purple coneflower (Echinacea purpurea L. Moench) seeds. The seeds that differ in seed size were either primed with moistened vermiculite (solid matrix priming) or primed in non-aerated −0.5 MPa polyethylene glycol 6000 solution at 25 °C for 6 days (osmopriming), followed by air-drying to their initial moisture level. The tetrazolium staining tests indicated that both large and small seeds were biochemically viable. No notable difference in germination percentage was found between large and small seeds. However, extensive cavity was visible in portions of small seeds in comparison with large seeds. Large seeds accumulated more antioxidants and had greater activities of anti-oxidative enzymes than small seeds. They also had greater isocitrate lyase and malate synthase activities than small seeds. As a result, large seeds had higher emergence percentage and faster emergence speed as compared to that of small seeds. Both solid matrix priming and osmopriming increased emergence percentage and shortened mean emergence time of purple coneflower seeds by increasing the activities of anti-oxidative enzymes and decreasing the levels of malondialdehyde and total peroxide accumulation. Moreover, priming also enhanced the anti-oxidative activities of treated seeds. The activities of isocitrate lyase and malate synthase were also increased in primed seeds. The enhanced anti-oxidation and lipid-carbohydrate conversion activities might explain in part why primed purple coneflower seeds emerged better than non-primed seeds.     

Temperature effects on corm dormancy and growth of Zephyra elegans D.Don

Experiments were performed with the Chilean geophyte Zephyra elegans, a potential cut flower, to evaluate the effect of corm weight and storage temperature on corm dormancy, and to determine the effect of day and night growing temperatures on its growth and flowering. Z. elegans has a deciduous and synanthous growth habit and the corm is replaced annually. Dormant corms were stored at different constant temperatures or temperature combinations from 20 to 40 °C. Corms released from their dormancy were grown at 15/10, 20/15, or 25/20 °C day/night temperatures. Corms of various weights were planted at the same date after being stored dry at 25 °C for 22 weeks. They all emerged 19–38 days after planting, showing that dormancy release was not affected by corm weight. A 20-week corm storage treatment at a constant 25 °C resulted in the most rapid corm sprouting. Sprouting percentage was reduced at higher or lower storage temperatures. Temperature also affected plant growth. When plants were grown at 15/10 or 20/15 °C they emerged and flowered more rapidly than when they were grown at 25/20 °C. The latter growing temperature also resulted in poor flower quality.     

Freezing temperature treatment induces bud dormancy in ‘Granny Smith’ apple shoots

One-year-old, ‘Granny Smith’ apple (Malus × domestica Borkh.) shoots were selected randomly from commercial orchards in 1999 and 2003, cold stored at temperatures between 1 and 13 °C for varied periods, following a 12/12 h freezing temperature pre-treatment of −1/13 °C (supposedly non-chilling temperatures) for 1 or 2 weeks. The rate of budburst, determined after forcing at 25 °C, was used to follow the progression of bud dormancy. The freezing pre-treatment clearly enhanced (deepened) bud dormancy in all experiments. Clearly definable influences due to the presence of leaves during the pre-treatment were not observed on shoots cold stored at chilling temperatures. Trees were defoliated before leaf drop in late summer/autumn under field conditions by hand (2001) and using a spray containing 3% urea and 1.8% zinc sulphate in 2003. In 2001 the first two hand defoliation dates significantly enhanced dormancy, while in 2003 chemical defoliation had no effect. These data indicate that the leaves are not clearly involved in the perception of factors that are responsible for dormancy induction. As with dormancy release it is possible that the perception of induction factors, i.e. low temperatures, and as shown in these data, freezing temperatures, occurs within the buds themselves.     

Promotion of seed germination and subsequent seedling growth of loquat (Eriobotrya japonica,Lindl) by moist-chilling and GA3 applications

The germination of loquat seeds faces certain problems. The present research was designed to study the promotion of the germination of loquat seeds by moist-chilling and GA₃ applications. The results showed that loquat seeds display an endogenous dormancy that can be released by moist-chilling treatment for a certain period. In this respect, the best treatment was moist-chilling for 3 weeks at 5 ± 1 °C or 1 week of moist-chilling followed by soaking in 250 ppm GA₃ solution for 20 h. These treatments significantly increased germination percentage (88 and 85%, respectively) and decreased time to 50% germination (T50) (31.5 and 40.7 days, respectively) compared to control (51% and 56 days, respectively). Also, the characteristics of the obtained seedlings were much better than the control seedlings. In addition, the 3-week moist-chilled seeds contained the highest soluble protein concentration and were characterized by the synthesis of new protein band of 161.7 kDa that was absent in all other treatments. This treatment lead to the absence of five polypeptides bands (222.5, 201.5, 109.5, 71.1 and 49.3 kDa), which were synthesized in GA₃ treatment, and the presence of a higher number of polypeptide bands compared with those of other moist-chilling periods and the control treatments. However, increasing the moist-chilling period over 3 weeks significantly decreased both germination percentage and T50. The combination between GA3 and moist-chilling treatments produced differential effects on seed germination, soluble protein and the number of protein bands depending on the length of the moist-chilling period. Although GA3 application on un-chilled seeds resulted in more synthesis of protein bands than other tested treatments, it did not improve the germination process. The concentration of soluble inorganic phosphorus of the tested seeds was negatively (r = −0.57^*) and the concentration of soluble organic phosphorus positively (r = +0.49^*) correlated with the germination percentage. It was concluded that treatment of moist-chilling for 3 weeks or 1 week moist-chilling followed by 250 ppm GA₃ is recommended for promoting the germination process of loquat seeds and improving growth characteristics of the subsequent seedlings.     

Bruising injury of persimmon (Diospyros kaki cv. Fuyu) fruits

This study was performed to monitor the deterioration of bruised persimmon (Diospyros kaki cv. Fuyu) fruits. Freshly harvested fruits were bruised by dropping them from a height of 50 cm onto a steel board and then stored at 0 or 20 °C in temperature controlled chambers for up to 4 weeks. Immediately after the bruising, no visible injury on the fruits was evident, but the fruits deteriorated rapidly during storage. The skin tissues of the fruits stored at 20 °C became more reddish with the duration of the storage, but no such changes were found with the fruits stored at 0 °C. The increase in redness of the skin tissues appeared to be associated with storage temperature, but not with the bruising. The skin tissues also became darker when stored at 20 °C than at 0 °C and this tendency was more obvious with the bruised fruits. Flesh firmness decreased rapidly during storage except for the non-bruised fruits stored at 0 °C. Even the non-bruised fruits rapidly lost their flesh firmness at 20 °C. No significant changes in lipid peroxidation, as expressed by malondialdehyde production, were found between the bruised and the non-bruised fruits during the storage either at 0 °C or at 20 °C. This implies that the fruit deterioration caused by bruising is not due to the consequences of lipid peroxidation. Polyphenol oxidase activity increased more rapidly in the bruised fruits than in the non-bruised fruits during storage. The bruising had more effect on increasing polyphenol oxidase activity than did the storage temperature. Although the increase in polyphenol oxidase activity appeared to be associated with the visual deterioration of the bruised fruits, it did not exactly correspond to the physical deterioration. These results indicate that polyphenol oxidase is not the only factor influencing the deterioration associated with bruising. Cell wall hydrolases are currently being assayed to determine if they also contribute the deterioration following bruising.     

Variability between silver thiosulfate and 1-naphthaleneacetic acid applications in prolonging bract longevity of potted bougainvillea

Potted bougainvillea ‘Purple Flower’ and ‘Taipei Red’ in four different stages of bract development were sprayed with STS (0.1, 0.5 mM) or NAA (25, 50 ppm) and were moved to low-light indoor conditions after treatment. The experiment was conducted twice, and the results showed that 0.5 mM STS and NAA (25, 50 ppm) could significantly prolong the longevity of bracts at certain stages in both cultivars. Treatment with 0.1 mM STS, however, had no effect on bract longevity of ‘Taipei Red’ at any stage. The prolonging effect of STS was more obvious in early bract stages and decreased as the bract stage increased, whereas NAA applications at later bract stages produced better results on prolonging bract longevity. The ethylene production rates of bracts in these two cultivars were higher in early stages and gradually decreased with bract growth. We propose that this phenomenon is related to the variability between STS and NAA in prolonging bract longevity of bougainvillea.     

Day and night temperatures,daily light integral,and CO2 enrichment affect growth and flower development of Campanula carpatica ‘Blue Clips’

Campanula carpatica Jacq. ‘Blue Clips’ plants were grown in a greenhouse under nine combinations of day and night temperatures created by moving plants every 12 h among three day/night temperatures (15, 20, and 25°C). At each temperature, there were three daily light integrals (DLI; 4.2, 10.8, and 15.8 mol m⁻² per day, averaged over the experimental period) created with varying supplemental light, and ambient (≈400 μmol mol⁻¹) and enriched (≈600 μmol mol⁻¹) CO₂ concentrations. Time to flower was closely related to average daily temperature (ADT), and was not significantly affected by the day or night temperatures delivered to achieve a specific ADT. Time to flower was not largely affected by DLI or CO₂ enrichment. As plant ADT increased between 15 and 25°C, flower diameter decreased about 1 mm per degree and was not related to the difference between day and night temperatures (DIF). Flower diameter was smallest and least sensitive to changes in temperature at lower DLI and at ambient CO₂ levels. There were 10 less flower buds and 0.3 g less dry mass per plant at first flower for every 1° increase in plant ADT at high and medium DLIs. Flower bud number and dry mass were relatively low and less sensitive to changes in ADT at low DLI, and increased slightly with CO₂ enrichment at medium and high but not at low DLI. Plant height was not related to ADT, but increased linearly as DIF increased from −6 to 12°C at all DLIs, but the response was stronger under low DLI than high and medium DLIs. Flower bud number and dry mass were correlated closely with the ratio of DLI to daily thermal time (base temperature of 0°C). Flower bud number and dry mass were highest when C. carpatica plants were grown at 15°C with a DLI of 10–15 mol m⁻² per day.     

Production of high quality Ardisia plants by stem tip cuttings

To produce commercially acceptable Ardisia plants, stem tip cuttings from mature plants were rooted and forced in greenhouses. Ten centimeter long cuttings were either treated with 200 ppm 1-naphthalene acetic acid (NAA) for 2 h, 2000 ppm indole-3-yl-butyric acid (IBA) for 10 s, or 0.5 and 1.0% IBA powder prior to sticking them in the rooting medium. Rooting percentage at 45 days exceeded 76% with 2000 ppm IBA treatment which was a significant increase over non-treated control. Rooted cuttings developed into three types of plants: those forming only vegetative shoots without flowers, those forming reproductive shoots with flowers, and those forming both vegetative and reproductive shoots. The ideal plant produced only vegetative shoots when rooted cuttings were transplanted into pots. About 50% rooted cuttings were forced to finish, producing 31 or 40% of high quality plants when rooted cuttings with vegetative shoots were grown in a greenhouse (GH) at temperatures higher than 21/19 °C (day/night) in 1995 or 21/18 °C GH in 1997, respectively. This method shortened the total production time to less than 2 years as compared to 4 years when starting from seeds.     

Effect of temperature on seed and fruit development in three mango (Mangifera indica L.) cultivars

The effect of diurnal maximum/minimum (20/10 or 25/15 °C) temperatures on seed and fruit development of ‘Irwin’, ‘Kensington’ and ‘Nam Dok Mai’ mangoes (Mangifera indica L.) was studied in a controlled-environment glasshouse. Exposure to low temperatures (20/10 °C day/night) 3 days after hand pollination significantly increased the percentage of stenospermocarpic fruit (nubbins), in which embryos were aborted at some stage during early fruit development. There were significant differences between cultivars in the percentage of nubbins produced out of the total fruit set following overnight exposure to 10 °C with 21% for ‘Nam Dok Mai’, 11% for ‘Kensington’ and 3% for ‘Irwin’. At 45 days after pollination, nubbin fruits were much smaller in size and weighed ca. 50% less than normal fruits. The lower percentage of nubbin fruits in ‘Irwin’ implies a greater adaptation to cool temperatures by this cultivar during fruit set and early embryo development.     

Storability of onion seeds and effects of packaging and storage conditions on viability and vigour

Fresh onion seeds desiccated to 6.0% seed moisture content (SMC) were stored in various packaging materials under different storage conditions. Seeds packed in aluminum-laminated pouches beside those stored with silica gel at 25 °C maintained satisfactory germinability and vigour after 12 months. Desiccated seeds stored in moisture impervious containers produced more vigourous seedlings. Germination potential of onion seeds increased with reduced SMC besides storage in moisture impervious packets along with desiccants as physiological and biochemical attributes are regulated. Seed viability and vigour decreased with accelerated ageing due to increased lipid peroxidation, decreased activities of several free radical and peroxide scavenging enzymes. Electrical conductance of seed leachates also increased with ageing. Thus, adoption of appropriate storage temperature and moisture control techniques would significantly affect onion seed quality, which was due to minimum accumulation of free peroxide radicals and enhanced activity of free radical scavenging enzymes.     

Rapid in vitro multiplication and conservation of Garcinia indica: A tropical medicinal tree species

A simple and efficient method has been developed for rapid regeneration of plantlets via adventitious bud differentiation on mature seeds of Garcinia indica (Thouars) Choisy, a medicinally important facultative apomictic tropical tree species. High frequency direct shoot proliferation was induced in seed segments cultured on Murashige and Skoog's medium supplemented with cytokinins (BAP, kinetin and TDZ) alone and in combination with auxin (NAA). Amongst the various combinations used, BAP proved to be the most effective. Multiple shoots formed within 4–5 weeks of culture. The shoot forming capacity of the seeds was influenced by the BAP concentration tested (5–50 μM) and optimal response was observed at different concentrations (12.5–50 μM) in different genotypes investigated. Significant differences were recorded in terms of percent response (27.78–100%) as well as average number of shoots per explant (3.49–57.67) among the four genotypes investigated. Elongation of the induced shoots was achieved on MS basal medium containing 0.2% activated charcoal. The induction medium had a profound effect on rate of bud elongation with shoots induced on lower concentrations of BAP showing as much as four-fold elongation within 4 weeks. Proliferating shoot cultures were established by repeatedly subculturing the shoot nodes on MS medium supplemented with 5 μM BAP. Maximum rooting (91.66%) occurred in shoots cultured on half-strength MS medium supplemented with 10 μM IBA. The plantlets were successfully transferred to soil after hardening; the time period from initiation of shoot buds to transplantation being 15–17 weeks. For in vitro conservation, the shoot cultures were maintained on medium supplemented with 0.5 μM BAP and the subculture duration could be enhanced up to maximum of 11 months.     

Effects of cold storage on postharvest leaf and flower quality of potted Oriental-, Asiatic- and LA-hybrid lily cultivars

The effects of cold storage of mature potted plants on postharvest leaf and flower quality were investigated in several cultivars of three major groups (Oriental, Asiatic and LA) of hybrid lilies (Lilium spp.). Mature plants were stored in darkness at 3 °C for 2 weeks before placing them in a postharvest evaluation room (22 °C) and were compared with plants moved directly to the evaluation room. The efficacy of GA₄₊₇ plus benzyladenine (BA) treatments (applied just before cold storage) for preventing cold-induced postharvest disorders in each cultivar was also evaluated. In all cultivars, cold storage caused several adverse effects on postharvest quality, including accelerated leaf yellowing or browning, bud abortion and reduced flower or inflorescence longevity. Leaf abscission was observed only in Oriental-hybrids. Treatment with GA₄₊₇ plus BA significantly reduced these disorders and improved the overall postharvest quality after cold storage. While different cultivars differed greatly in their sensitivity to cold storage, all the cultivars benefited from GA₄₊₇ plus BA treatment. Experiments indicated that GA₄₊₇ plus BA treatments could be applied as early as 2 weeks before the mature bud stage without compromising the positive effects.     

Methods to overcome seed dormancy in Echinacea angustifolia DC

Some factors (light, prechilling, gibberellic acid, ethylene) affecting germination of seeds of Echinacea angustifolia DC. were investigated. Without any pretreatment, the seeds germinated better in darkness than in light, however, percentages germination were low in both cases. GA₃ did not increase germination in light. Prechilling for 7–15 days in light or in darkness hardly affected percentage germination but significantly increased the rate of germination. Ethephon during prechilling resulted in a large increase of percentage and rate of germination in light, but had hardly any effect on germination in darkness. The results showed that a prechilling treatment for about 11 days at 5°C in a 1 mM ethephon solution in continuous light, followed by a 2-week germination period in light (24 h per day) at 20/30°C, can induce >90% seed germination in E. angustifolia. The prechilling treatment in ethephon also increased the rate of germination.     

In vitro production of Prunus necrotic ringspot virus-free begonias through chemo- and thermotherapy

Prunus necrotic ringspot virus (PNRSV)-free Begonia spp. plants were raised from petioles of virus-infected plants using in vitro techniques. The petioles were grown on MS medium supplemented with 0.2 mg/l NAA and 0.2 mg/l BAP (pH 5.8). For rooting, half-strength MS medium without any plant growth regulators was used. On rooting medium, shoots were subjected to chemotherapy (virazole, 2-thiouracil or 6-azauracil) and thermotherapy (38 °C for 16 h light period and 22 °C for 8 h dark period) separately or in combination. Regenerated plants (treated with chemo- and thermotherapy) were indexed for PNRSV by DAS-ELISA and RT-PCR. An amplified product of 785 bp was obtained by RT-PCR in PNRSV-infected plants. Virazole at a concentration of 20 mg/l was found to be more effective (30 and 20% of PNRSV-free plants as indexed by ELISA and RT-PCR, respectively) in comparison to the other chemicals. Thermotherapy for 25 days gave 35 and 25% PNRSV-free plants as indexed by DAS-ELISA and RT-PCR, respectively. A combination of both treatments gave a good number of PNRSV-free plants (67.5 and 57.5% as indexed by DAS-ELISA and RT-PCR, respectively). At higher concentrations all three chemicals were found to be toxic. Thermotherapy for more than 25 days caused browning of leaves and shoots died.     

Embryo induction via anther culture in papaya and sex analysis of the derived plantlets

We investigated the embryo induction of papaya by anther culture, and identified the sex of plantlets derived from embryos using a sex-diagnostic PCR. Anthers, containing approximately 80% uninucleate pollen, were collected from 10 to 14 mm long male flower buds. They were pre-treated on agar (0.8%) or in liquid medium for 1–5 days at 25 or 35 °C, then transferred to agar medium with 0.1 mg l⁻¹ BA and 0.1 mg l⁻¹ NAA. Agar and liquid media used for the pre-treatment contained water only or MS nutrients with or without sucrose (2.0%). On the agar medium, no embryos were induced at any pre-treatment temperature. In the liquid medium at 25 °C, embryos were induced at about 1.0% (rate of anthers forming embryos) in MS medium with sucrose for 3 or 5 days. At 35 °C, embryo induction rate tended to increase up to about 4.0% when anthers were treated in water for 1 day or MS medium with sucrose for 3 or 5 days. The sex of plantlets established through anther culture was analyzed using a sex-diagnostic PCR. All plantlets were determined as female. From these results, we suggest that all plantlets established through anther culture were of microspore origin, and that the anther culture technique is useful for the breeding of female papaya.     

Temperature and irradiance effects on Sandersonia aurantiaca flower shape and pedicel length

Sandersonia flowers can vary from being lantern- to tubular-shaped. Lantern-shaped flowers are considered to be most commercially desirable when the ratio of the widest to the narrowest diameters of a flower, termed the ratio of hips to waist, is 1.5 or greater. Pedicel length can also affect the overall appearance of a flower stem. Short pedicels are considered more desirable. The influences of temperature and irradiance on Sandersonia aurantiaca flower shape and pedicel length were examined in controlled environment (CE) growth rooms. The growing environments were at constant temperatures of 15, 18, 21, 24 or 27 °C; or day/night temperature differentials of −6, 0, +6, +12, or +18 °C, with a mean of 21 °C. Photosynthetic photon flux densities (PPFD) were 700, 460 or 210 μmol m⁻² s⁻¹. At harvest, measurements were made of the widest and narrowest diameters of the oldest flower on each stem and the ratio of these parts was calculated. The pedicel length of the oldest flower was also measured. Environments with constant temperatures below 23 °C and the least day/night temperature differentials (−6, 0 and +6 °C) produced flowers of the most desirable shape, defined as having a hips to waist ratio of 1.5 or greater. At these temperatures, irradiance had a variable effect on flower shape. Pedicel length was also highly dependent on temperature and PPFD. As mean temperatures increased or as the temperature differential changed towards a differential of 12 °C, and as PPFD decreased, pedicel length increased significantly. Hip diameter was more sensitive to environmental changes than waist diameter and thus had a greater effect on flower shape. This work indicates to growers that they can enhance Sandersonia flower quality by producing more desirably shaped flowers with short pedicels through maintaining relatively low (less than 23 °C) mean temperatures, minimising temperature differentials, and maintaining irradiance levels as high as possible.     

Improvement of in vitro micropropagation of Lilium oriental hybrid ‘Casablanca’ by the formation of shoots with abnormally swollen basal plates

Bulb scales of Lilium oriental hybrid ‘Casablanca’ were cultured on MS medium supplemented with cytokinins (kinetin, BA (benzyladenine), TDZ (thidiazuron)). The basal part of bulb scales swelled and formed adventitious shoots with foliage small, leafy bulb scales and abnormally swollen basal plates on the media with cytokinins. Shoots were formed rapidly from the basal parts of bulb scales and became shoot clusters. The medium containing 2.2 μM BA was most favorable in the shoot formation from bulb scales. Cutting shoots into small segments (7–8 mm wide × 12–15 mm length) were cultured on media containing BA and IAA (indole acetic acid) and the segments regenerated many new shoots and formed shoot clusters. The shoot section to shoot cluster cycle method improved adventitious shoot proliferation. The media supplemented with 4.4 μM BA and 5.7 μM IAA. or 8.9 μM BA and 0.6–2.9 μM IAA were effective in allowing the proliferation of shoots from shoot segments under light condition. Sucrose and activated charcoal (AC) improved bulblet growth. Bulblet growth was effectively performed on MS medium containing 60 g/L sucrose. Bulblet growth was also improved by the supplement of AC. The medium with 2.0 g/L AC was most effective for bulblet growth. Normal bulblet growth was stimulated more by the culture of shoots than that of bulb scales. Bulblet weight from shoots reached to an average of over 1100 mg of a bulblet after 3 months in culture on MS medium containing 60 g/L sucrose and 2 g/L AC. Most of the bulblets produced by this method generated stems with several leaves in the green house, after cold treatment at 5 °C for 3 months.