Factors influencing the transplantation success of micropropagated narcissus bulbils

The transplantation phase of narcissus micropropagation was studied using bulbils from bulbing shoots sub-cultured to hormone-free bulbing medium. Transplantation success was enhanced by the incorporation of activated charcoal in the medium, culturing the shoots at a constant 20°C and subjecting bulbils to a period of cold storage at 5°C to overcome dormancy prior to planting out. These measures gave overall figures for transplantation success in a large-scale evaluation experiment of 47.8-81.2% depending on cultivar. Greatest success was achieved using bulbils weighing more than 0.2 g. However, the overall proportion of such bulbils was only 0.19 to 0.20. Early leaf senescence, which limits bulbil growth in culture, appeared to be linked with initial bulbing shoot weight. The beneficial effects on transplantation of using full-strength mineral salts over halfstrength salts and of using one particular clone of cv. St. Keverne, were probably mediated via effects on final bulbil weight. Elevated concentrations of sucrose in the bulbing medium gave no benefit even though final bulbil weight was increased. High sucrose levels gave earlier shoot senescence and increased dormancy. Culture of bulbils in darkness did not effect final bulbil weight but was extremely detrimental to transplantation success. Most unsuccessfully transplanted bulbils showed a foliar growth phase suggesting a premature re-entry into dormancy. With few exceptions, bulbils judged to have been successfully transplanted grew on without problem in their second year.     

A new garlic growing system from bulbils through transplanting

Summary

We have developed a new garlic growing system from bulbils through transplanting. By this system, extremely small seed bulbils produced bulbs as large as those from cloves of bulbs. In the new system, the bulbils harvested in summer and stored at 18–20°C in winter are grown from the following spring to summer in paper pots, and then transplanted to the field. In Hokkaido, northern Japan, July transplanting produced larger bulbs than August or September transplanting, and the bulbs produced were almost the same size as those of traditional growing methods. One bulbil weighed 75.3±5.6 mg and 84.2±5.4 mg in cv. Furano and a clone, No. 205, respectively, while one clove weighed 5–7g. A clone, H500, produced bulbs of 79.9±3.0.g although its original bulbil weighed only 15.4±0.8.mg. Moreover, this clone produced a great number of bulbils, 250–300, per plant.     

Temperature and development in Iris × hollandica during preplanting storage. I. Leaf initiation

Summary

Leaf initiation was examined in Dutch iris bulbs during pre-planting storage temperature treatments in the dark. The number of leaves initiated before inflorescence evocation increased with increasing temperature. The base, optimum and maximum temperature for leaf initiation were established as –0.4, 13.1 and 26.7°C respectively. The rate of leaf initiation was shown to be linearly related to temperature. The average thermal-time required for each leaf to be initiated under constant temperatures was 79°Cd but leaves initiated during the transfer temperature treatments required an average of 92°Cd. Rates of leaf initiation predicted from thermal-time equations were similar to those observed in bulbs stored at the lower temperatures (2–13°C) but rates observed at warmer temperature (17–25°C) never reached the predicted high value.     

Temperature effects on flower formation in saffron (Crocus sativus L.)

The temperature conditions for shoot growth and flower formation were characterised for saffron (Crocus sativus L.). Leaf withering occurred during late winter or spring depending on location, and coincided with a rise in temperature. No growth was detectable in the buds during the first 30 days after leaf withering, neither in underground corms nor in lifted corms incubated in the laboratory under controlled conditions. Flower initiation occurred during the first growth stages of the buds. The optimal temperature for flower formation was in the range from 23 to 27 °C, 23 °C temperature being marginally better. To ensure the formation of a maximum number of flowers, the incubation at these temperatures should exceed 50 days, although incubation longer than 150 days resulted in flower abortion. Flower emergence required the transfer of the corms from the conditions of flower formation to a markedly lower temperature (17 °C). Incubation of the corms after lifting at a higher temperature (30 °C), reduced flower initiation and caused the abortion of some of the initiated flowers. No flowers formed in corms incubated at 9 °C. A variable proportion (20–100%) of the corms forced directly at 17 °C without a previous incubation at 23–27 °C formed a single flower. The wide differences in the timing of the phenological stages in different locations we found in this study seemed related to the ambient temperature. Leaf withering was followed shortly by flower initiation, which occurred during late spring or early summer as the rising temperature reached 20 °C. A long hot summer delayed flower emergence which occurred in late autumn as the temperature fell to the range of 15–17 °C.     

Warm Storage of Narcissus Bulbs in Relation to Growth,Flowering and Damage Caused by Hot-Water Treatment

Three experiments are described on the effects on flowering of warm storage of narcissus bulbs before (and in some cases after) hot-water treatment (h.w.t.) against eelworm infection. Almost complete loss of the flower crop occurs if the bulbs are not warm stored, compared with the production of about 90% marketable flowers following warm storage. Optimum temperatures and durations of warm storage are not clearly defined; there is very little difference between the two recommended treatments, 34° C. for 3 days and 30° C. for 7 days, with the latter giving slightly better results. In another experiment, best results were obtained following 32·5° C. for 8 days or 35° C. for 5 days, with some varietal differences. These combinations were superior to most at 30° C., and to all of only 2 days duration. Higher temperatures and longer durations generally result in earlier flowering, with no adverse effect on flower quality. Bulb yield in the field following h.w.t. is higher when the bulbs are warm-stored before h.w.t. and, when forced in the following season, they give more flowers. Post-h.w.t. warm storage reduces flower quality and bulb yield in the field; although some minor benefits were observed, this treatment cannot be recommended. The possible mechanism for the protection afforded by warm storage is discussed.     

Effect of chilling on runner formation and flower initiation in the everbearing strawberry

Fresh and cold-stored plants of the everbearers ‘Rabunda’ and ‘Ostara’ were placed for 90 days, from the end of August, in glasshouses of the IVT phytotron at 14, 20 and 26°C and a daylength of 16 hours.In the fresh plants hardly any runners were formed at 14 and 20°C, but flowers were initiated, while at 26°C both runners were formed and flowers initiated. In the cold-stored plants, runners were formed first and thereafter flowers were initiated at all temperatures.It was concluded that (1) chilling induces runner formation, but can be replaced by high temperature, and (2) chilling delays flower initiation.     

山药珠芽生长过程中激素和糖类物质含量的变化

 测定了不同生长阶段的山药（Dioscorea opposita）珠芽内源激素IAA、ZR、DHZR、GA₃和ABA的含量,以及还原糖、可溶性糖、淀粉和干物质的含量,研究其变化规律。结果表明,珠芽生长期IAA和DHZR含量低,变化小。ZR的含量一直比DHZR高,且变化大,尤其在珠芽生长初期含量下降快。与其它激素相比,GA₃含量较高,生长初期呈上升变化,随后缓慢下降,当生长停止时其含量仍较高（1 220.7 ng · g^-1）。珠芽完全变褐前,ABA的含量在730.9 ~ 954.9 ng · g^-1间波动,在珠芽完全变褐至生长停止期间急剧上升。珠芽开始褐变前,还原糖含量迅速下降,以后变化较小。珠芽生长过程中可溶性糖含量呈曲线上升;淀粉和干物质含量呈直线缓慢上升,当珠芽成熟时可溶性糖、淀粉和干物质含量达到最高。山药珠芽的生长需要高水平的GA₃和ZR,当GA₃/ABA小于1时,珠芽趋于成熟;茎蔓枯黄珠芽才停止生长,糖、淀粉等物质的积累才终止。     

榛子新品种‘辽榛1号’

‘辽榛1号’为平榛与欧洲榛的种间杂种,具有平榛的抗寒性强、栽培适应性强,以及欧洲榛的坚果大、果壳薄、出仁率高、丰产等特点;适宜在北纬41°~32°,年平均气温8~14℃的地区及其相似气候条件区域栽培。     

Manipulation of bolting and flowering in celery (Apium graveolens L. var. dulce). II. Juvenility

After germination, a juvenile phase of development was apparent in cvs New Dwarf White and Celebrity. During this incompetent phase, plants were not induced flower even when subjected to chilling at 5°C for nine weeks. Juvenility ended and the plants became competent to perceive chilling as a vernalization stimulus when they had initiated 17 leaves including leaf primordia in cv. New Dwarf White and between 17 and 20 leaves in cv. Celebrity. After phase transition, the level of competence was not affected by plant age. The rate of leaf initiation in cv. New Dwarf White during juvenile and competent vegetative growth related linearly to temperature, increasing between 3 and 22.8°C and then declining over the range 22.8 to 37.4°C. The first 17 leaves of celery cv. New Dwarf White had longer plastochrons of 43° Cd (>3°C) each than subsequently initiated leaves with 29° Cd for each leaf. The thermal time requirement for completion of juvenile development after radicle emergence was 731° Cd> 3°C. In cv. Celebrity the first 17 leaves required 42° Cd each for initiation.     

Effects of night temperature on floral initiation and raceme development in macadamia

The effects of night temperature on floral initiation and raceme development in macadamia (Macadamia integrifolia Maiden and Betche) were examined under controlled-environment conditions. Warm nights (20°C compared with 15 °C or less) just prior to and after floral initiation, followed by low ambient night temperatures (mean 10.5 °C) prior to anthesis, promoted floral bud production over an extended period of time. The rate and extent of early raceme elongation, and hence the number of flowers produced per raceme, was greater under warm nights. Despite differences in the number of racemes (and flowers) produced, the number of nuts set per tree were not significantly different. It is suggested that excess flower production may represent a waste of metabolic activity.     

Prevention of hot-water treatment damage in narcissus bulbs by pre-warming

Summary

Hot-water treatment (HWT) used to control stem nematode in narcissus bulbs can lead to yield loss through damage to flower, leaf and root initials. Warm storage of bulbs, usually at 30°C, reduces this damage. The effects of two pre-warming treatments (18°C for two weeks or 30°C for one week before HWT) were investigated in bulbs hot-water treated at a range of dates (from early-July to late-September). Experiment 1 was conducted on bulbs of cv. Carlton lifted on three dates. In the year after HWT, flower numbers were much reduced when HWT was applied after mid-August following storage at ambient temperatures, or after late-August following storage at 30°C, but numbers were only slightly reduced even with late-September HWT when given after 18°C storage. Pre-warming was somewhat more effective after early lifting. Late HWT reduced yields of bulbs harvested after two years' growth, but 18°C treatment largely prevented these losses. In Experiment 2, the beneficial effects of 18°C treatment were confirmed in cvs Carlton and Golden Harvest but not in cv. Barrett Browning. These findings are discussed in terms of growth retardation by warm temperatures.     

Cold treatments enhance responsiveness to gibberellin in stock (Matthiola incana (L.) R. Br.)

Summary

Endogenous GAs have been suggested as regulators of stem elongation and flowering of cold-requiring plants. Here, the relationship between temperature conditions and responsiveness to GA₄ on stem elongation and flowering of stock (Matthiola incana) was investigated. The optimum temperature for induction of flower bud initiation was 10°C, and the minimum duration was 20 d in the late flowering cv. Banrei; the type of cold treatment effect on flowering was classified as a “direct effect”. Stem elongation was markedly promoted by cold treatment regardless of flower bud initiation. The cold treatment amplified the stem elongation response to GA₄. The GA₄ level necessary for flower bud initiation was lower in the 10°C treatment than in the 15°C treatment, and it became lower at longer durations of cold treatment. These results indicate that the cold treatments enhance responsiveness to GA₄ not only in the stem elongation process but also in the flower bud initiation process and that the development of responsiveness to GA₄ may correlate with the temperature and duration of cold treatment.     

A hypothesis to explain the relationship between low-temperature treatment,gibberellin activity,curd initiation and maturity of cauliflower

The effects of cold-treating young cauliflower plants (Brassica oleracea var. botrytis L.) of the cultivars ‘Lero’, ‘Lawyna’, ‘Novo’ and ‘Janavon’, on gibberellin activity and the spreads of curd initiation and maturity are described and discussed in relation to other similar work.Exposure of plants to 0°C for 15 days increased gibberellin activity in the apices of ‘Lero’ and ‘Lawyna’ plants. The spreads of curd initiation and maturity of ‘Lawyna’ were significantly reduced by cold-treatment at 0°C, but ‘Lero’ was not affected, possibly because plants had initiated too many leaves and were thus beyond the stage receptive to low-temperature treatment. This treatment had no effect on gibberellin activity nor on the spreads of curd initiation and maturity of ‘Novo’ or ‘Janavon’, probably because plants had not reached the sensitive stage when cold-treated.It is postulated that the phase of growth during which the curd-initiation period can be shortened by cold treatment is specific for each cultivar, and other data were used to confirm this. It seems likely that the receptive phase occurs at higher leaf-numbers with cultivars which take longer to initiate curds.     

Effects of pre- and post-bloom temperature regimes on development of Lilium longiflorum Thunb.

Glasshouse grown ‘Ace’ and ‘Nellie White’ Easter lily plants were subjected to different temperature regimes to determine temperature requirements during pre- and post-bloom development. Rate of leaf- and flower-bud development and stem elongation on the primary (mother) axis were directly proportional to the range of temperatures used (6–24°C), and were equally effective in predicting crop development. Scale initiation on the secondary (daughter) axis during pre-bloom phases was proportional to growing temperature, reaching maximum activity at 18°C in ‘Ace’ and at 12°C in ‘Nellie White’. The shift from scale to leaf initiation and development following anthesis was favored by 12 rather than 18°C with significant reductions in leaf initiation in both cultivars at 24°C. No difference in secondary meristem diameter occurred with temperature during pre-bloom, but large dome size was associated with 12°C or lower during the post-bloom phase. Primary scale weight increase (filling), reached a maximum 50 days following anthesis, and was greatest at 18°C. Secondary scale filling reached a maximum 80 days after anthesis at both 18 and 24°C. The secondary axis became increasingly responsive to sprout-inducing temperatures with increasing age and development. Fifty days after anthesis, 12 and 18°C were equally effective in sprouting ‘Ace’ bulbs, while 12°C was more effective with ‘Nellie White’. Early leaf senescence, associated with high (24°C) temperature, did not favor increased bulb size, daughter leaf primordia count and meristem diameter, or sprouting.     

Influence of Early-Season Temperature on the Growth and Branching of Newly-Grafted Apple Trees

Newly-grafted trees of apple cv Discovery on MM.106 were grown in pots at 25°C before transfer to growth rooms at 20°C; some were then subjected to 5 or 10 d at 10°C. The continuous 5-d cool period stimulated branching without reducing main shoot growth but the 10-d cool period reduced main shoot growth and did not stimulate branching. Subjecting similar plants to a night temperature of 0°C for various periods also stimulated branching but the number of cold nights and the stage of scion shoot growth influenced the magnitude of the response.     

Flowering in pyrethrum (Tanacetum cinerariaefolium L.). I. Environmental requirements

SUMMARY

Floral evocation in pyrethrum {Tanacetum cinerariaefolium) is stimulated by a period of vernalization. Night temperatures of 6°C and 12°C for two weeks and three weeks, respectively, promote rapid inflorescence initiation and development. A night temperature of 18°C does not satisfy the vernalization requirement. Longer periods of vernalization stimulate more rapid inflorescence initiation and development and result in a larger number of inflorescences being initiated. The vernalization stimulus may be modified by the daily light integral. Both inflorescence initiation and inflorescence development are promoted by long days. The number of leaves formed before flower bud initiation is not affected by daylength. Night-break lighting does not promote flowering. It is suggested that the stimulatory effect of long days may be in supplying photosynthetic assimilates to the developing meristems. Floral development is retarded by low photon flux density conditions regardless of day temperature. High day temperatures (25°C) combined with low photon flux (350 umol m"2 s"' or less) prevented pyrethrum from flowering in otherwise inductive conditions.     

Effects of Environment on Flower Initiation in Carnation

The main object of the investigation was to attempt the separation of effects of photoperiod and total incident light energy in controlling flower initiation in the glasshouse carnation, variety White Sim.

Low light intensities delayed flower initiation. The delay was associated with reduced rates of growth in terms of dry weight, reduced rates of leaf initiation and increased number of leaves formed below the flower. Short days also delayed flower initiation and increased the number of leaves formed below the flower. Photoperiod, however, had no appreciable effect on growth in terms of dry weight or on rates of leaf initiation, but internode length was greater in long days than in short days. A period of illumination given in the middle of the night was more effective in promoting flower initiation than an equivalent period given to extend the day. Internode length was similar in these treatments. Effects of night temperature were less consistent than those of light intensity or daylength but, under most of the conditions tested, high night temperatures (minimum 65° F. (18° C.)) delayed flower initiation and increased the number of leaves formed below the flower. Low temperature treatment of plants at 40° F. (4.5° C.) for one month promoted subsequent flower initiation and reduced the number of leaves formed below the flower.     

Controlled Environment Cabinets for Experiments with the Cultivated Mushroom

Apparatus for the study of the effects of temperature, relative humidity and rate of ventilation on the initiation and development of sporophores of the cultivated mushroom is described.

At low rates of ventilation the initiation of primordia was delayed, the yield was reduced, and the sporophores were more spindly as compared with those given higher rates of ventilation.

The number and total weight of sporophores were greater at high relative humidities (80-95%) than at low (40-50%).

The number and total weight of sporophores were greater at 65° F. than at 70° F.     

Changes in the contents of phenolic substances,phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) accompanying chilling-injury of eggplant fruit

The mechanism of browning, which is a typical chilling-injury of eggplant fruit (Solanum melongena L.), was investigated by determining the changes of phenolic substances, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) either during storage at 1°C or after exposing fruit to low temperature for various periods.Chlorogenic acid and its isomer, the main substrates for browning, were isolated from eggplants by column and paper chromatography. R_f values and various color reactions of the above acids were compared with those of authentic chlorogenic acid.After 2 days of cold storage at 1°C, when browning was initiated, chlorogenic acid content decreased to less than half that of the initial day, rose to a maximum after 4 days, and then decreased rapidly.PAL activity increased to a peak after 2 days at 1°C, then decreased over 10 days as browning increased. TAL activity also increased after transfer from 1°C to 20°C.It is suggested that rapid turn-over of chlorogenic acid occurs in the early stage of cold storage of eggplant fruit, and development of browning is closely related to chlorogenic acid, PAL and TAL.     

The Effect of Cold Storage and Treatment with Gibberellic Acid on Flowering and Bulb Yields of Dutch Iris

Iris bulbs of the varieties Wedgewood and Prof. Blaauvv were injected with 50 or 500 μg. gibberellic acid (GA) before or after cold storage (10° C.) of 18 or 35 days. GA injection accelerated flowering by up to 19 days ; it had little or no effect on length of leaves or flower stem. It was most effective when applied at an early stage after flower initiation.

GA injection reduced bulb yield of Wedgiwood plants, and had no effect on, nor increased bulb yield of, Prof. Blaauw plants.

GA spraying (seven times at 10^-2M of GA) accelerated flowering and increased foliage growth in both varieties. It increased flower stem elongation and reduced bulb yield in Wedgfcwood plants.