Mother Bulb Research Articles

COMPETITION BETWEEN SPROUT AND DAUGHTER BULBS FOR CARBOHYDRATES IN TULIP AS AFFECTED BY MOTHER BULB SIZE AND CYTOKININS

Planting of large mother bulbs resulted in large tulip flowers, planting of small mother bulbs in small tulip flowers. However, a heavier bulb gave a relatively lighter tulip flower, indicating different mechanisms for the redistribution of fresh weight and dry weight. The possibilities to grow good quality tulips from small sized bulbs were investigated in terms of source sink relationships, for a “splitting” cultivar, cv. Apeldoorn, as well as for a “non-splitting” cultivar, cv. Parade. Over the period between planting and flowering, the recovery percentage of dry matter in generative bulbs depended on the size of the mother bulb, changing from about 70 to 60% for bulb size 14 to 8 respectively. The distribution of dry matter at the moment of flowering also depended on the size of the mother bulb. In small sized (8) bulbs about 85% of dry matter was transported to the tulip flower, in big sized bulbs this percentage was about 40%, resulting in different amounts of dry matter left in the scales. The percentage dry matter transported to the daughter bulbs never exceeded 12% at the moment of flowering. Tulip flowers grown from big sized bulbs also contained a higher percentage dry weight than tulips grown from a small sized mother bulb. Removing scales from a big sized tulip bulb before cold treatment or immediately before planting, resulted in a system comparable to small sized mother bulbs: slightly more dry matter was lost in the period from planting to flowering, a higher percentage of dry matter was transported to the tulip flower, and the tulip flower itself contained a lower percentage of dry weight. Injection of tulip bulbs with benzyladenine (BA) immediately before planting resulted in a higher FW of the tulip flowers. As the DW of the tulips did not increase, this result is due to a higher water uptake. Therefore, the redistribution of DW from source to sink was unaffected by application of BA.

Annual Growth and Development of Scilla peruviana

Scilla peruviana is a bulbous plant whose distribution extends from South Africa, into Europe and Asia. It belongs to the family Liliaceae (subclass Monocotyledonae). S. peruviana is an attractive floral species with excellent commercial potential, but it does not produce many bulblets and its multiplication rate is very low. Increasing the multiplication rate, and regulation of its growth and development, cannot be achieved without knowledge of its basic patterns of ontogenesis. We studied the annual growth and development of S. peruviana, from initiation until differentiation, giving special attention to cytological changes at the apical meristem. We also investigated the cytophysiological changes occurring in scales during ontogenesis. Two generations of daughter bulbs are present in each mother bulb. Flowering of the mother bulb coincides with vegetative development of the apical meristem of the primary daughter bulb (March-April). During gradual senescence of leaves and roots of the mother bulb, the apical meristem of the primary daughter bulb undergoes a transition from vegetative to prefloral development (June). Intensive flower organ differentiation occurs in the daughter bulb during the mother bulb's rest period (July–August). Initiation of the apical meristem of the secondary daughter bulb occurs within the primary daughter bulb, which is itself enclosed within the mother bulb (August). The development of the apical meristem of a daughter bulb, from its initiation until flowering, thus occurs without interruption and takes ≈20 months. By modifying external factors such as temperature and growth regulators, we can now control time of flowering and increase the multiplication rate of S. peruviana.

Effect of Ambient Temperature on the Growth and Development of Amaryllis(Hippeastrum hybridum hort.) Bulbs.

How different day/night temperature affect the growth and development of the vegetative and reproductive parts, including the bulbs of amaryllis (Hippeastrum hybridum) plants in growth chambers for two years was investigated. One-year-old, 2-leafed seedlings were transferred to growth chambers set at 17 °/12°C (low, L plot), 24°/17°C (middle, M plot) and 30/24°C (high, H plot) under natural daylength.1. High temperatures (H plot) hastened the unfolding and elongation of leaves, and increased markedly the growth of mother bulb and daughter bulbs, but the plants did not flower.2. In plants exposed to low temperature (L plot), the leaves were the slowest of the three plots to unfold and elongate; the mother bulbs were slow to enlarge but produced the most daughter bulbs. The temperature favored floral development.3. Middle temperature (M plot) educed intermediate vegetative growth and the enlargement of mother and daughter bulbs. This condition was optimum for flower stalk elongation and flowering.Thus, comparing the responses of amaryllis grown under low, middle, and high day/night temperatures, high temperature favored promotion of mother bulb enlargement, but the moderate and low temperatures were optimum for bulb and flower production.

Effects of Benzyladenine, Temperature, and Bulb Diameter on Twin-scale Propagated Amaryllis

Four bulb sizes of Hippeastrum hybridum `Appleblossom' were twin-scale propagated, soaked in 0, 0.01, 0.1, and 0.5 g·liter–1 of benzyladenine (BA), and incubated at 15, 20, 25C and a fluctuating temperature of 31C day, 21C night. Bulbil numbers were recorded following incubation and leaf emergence after bulbils were planted. Eight weeks after bulbils were planted, bulb diameter and leaf numbers were observed. BA application had no effect on bulbil initiation. However, bulbil formation per twin-scale cutting increased as temperature (up to 25C) and mother bulb diameter increased. Bulbil diameter and survival of bulbils increased as incubation temperature increased up to 20C. After planting bulbils, leaf emergence was hastened as bulb size decreased.

自生ササユリ球根の発育とりん片培養による子球形成との関係

Experiments were conducted to clarify the relationship between seasonal changes in bulb growth of Lilium japonicum Thunb. in the field under natural conditions and bulblet formation on in-vitro cultured scales.When scales are detached from a bulb, vestiges of stems from past years are detectable on the basal plate. The year, the scales were formed, was identified by the positions of the residual stems on the basal plate. Each year, a new daughter bulb, consisting of about 7 scales, which develops within the mother bulb and the growth of the new shoot, which occurs between April and July, consume 3 to 4 outer-scales of the mother bulb.The bulbs were collected on 10 March, 1 July and 14 October, and their scales cultured for 13 weeks. The rate of bulblet formation on the scales collected on 10 March was fastest. The formation rate and fresh weight gain of the regenerated bulblets, which formed on the outer scales, were faster than those on the inner scales.We conclude that to regenerate bulblets by in-vitro scale culture, early spring is the optimum time to collect the bulbs.

PROPAGATION OF AMARYLLIS BULBS BY TWIN SCALING

Amaryllis bulb production is conducted in Africa, and to a lesser extent in Central America, Holland and Israel. Preliminary studies have shown bulb production is feasible in zone 6b using unheated greenhouses and thermal blankets during cold periods. Spun bound polyester (Reemay) and polystyrene foam (Sentinel) provided a maximum of 9C protection over outside conditions. Amaryllis bulbs have been uninjured during two successive winters. A twin scale propagation experiment was conducted on the cultivar Appleblossom. Cuttings 15mm wide that were placed in closed, vermiculite-filled plastic bags or uncovered, vermiculite-filled plastic trays produced 1.5 bulbs per cutting. Cuttings 7.5mm wide that were placed in soil in plastic bags or open flats averaged .34 bulbs per cutting. From 75 to 80 bulblets were produced per mother bulb using wide cuttings in soil or vermiculite or narrow cuttings in vermiculite.

Effect of Scale Position on the Mother Bulb on "in vivo" Multiplication of Bulblets from Bulb-Scales of Different "Lilium" Species and Hybrids.

Effect of Scale Position on the Mother Bulb on "in vivo" Multiplication of Bulblets from Bulb-Scales of Different "Lilium" Species and Hybrids.

Vegetative spreading ofOxalis pes-caprae (Oxalidaceae)

The underground movement ofOxalis pes-caprae L. is a combination of shoot elongation and root contraction. Its function is the dispersal of renewal bulbs located in the axils of the scale leaves. At the beginning of root contraction the bulb leaves become detached from the bulb bottom and remain at their initial position. Bulb bottom and contractile root form a turnip-shaped unit. Its proximal end becomes displaced by shortening of the root. While contracting, the root develops a pulling force, which is quantified by using the lifting method. Connection between the overground shoot and the contractile root is maintained by a few short basal internodes of the new shoot, which elongate to form a thin underground “thread”. Elongation of the thread and shortening of the root reach 20–30cm and obviously occur synchronously, whereby the thread remains taut during movement. Along the thread several lateral buds emerge. These develop into renewal bulbs usually reaching the size of the mother bulb.

THE ENVIRONMENT UNDER WHICH THE STOCK PLANT IS GROWN INFLUENCES EXPLANT PERFORMANCE IN VITRO

Environmental factors under which the stock (mother, donor) plant has been grown, including temperature; light duration, quality, and intensity; mineral nutrition; and ambient gases can have significant impact on explant responses in vitro. Bulblet production in hyacinth has been influenced by mother bulb storage temperature. Shoot proliferation and rootability of microshoots of rhododendron have been modified by light intensity and light quality. Photoperiod has been demonstrated to affect tuber and callus formation on potato and dahlia. Furthermore, plant growth regulator treatments of the stock plant can strongly influence in vitro responses of explants taken from such plants. Implications of these latter responses will be discussed with regard to possible endogenous hormonal activity.

Studies on the Development of New Ornamental Allium through Interspecific Hybridization. I. Evaluation of Commercial Ornamental Allium for Adaptation to Kagoshima Conditions.

The vegetative and reproductive performances of Allium aflatunense 'Purple Sensation', A. albopilosum, A. cowanii, A. elatum, A. giganteum, A. moly, A. neapolitanum, A. oreophilum var. ostrowskianum, A. roseum and A. stipitatum were evaluated in Kagoshima, southern Japan, from October 1990 to May 1991. A. cowanii, A. neapolitanum and A. roseum emerged during autumn, whereas the rest emerged in the spring. A. datum, A. oreophilum var. ostrowskianum and A. stipitatum failed to flower. Sexual reproduction through selling or interspecific crossing failed to produce normal mature seed. Except for A. cowanii, A. giganteum, A. neapolitanum and A. roseum, marked physiological dysfunction in the rest of the species was indicated by the much reduced bulb weights at harvest as compared to the mother bulb weights. With A. albopilosum and A. giganteum, planting large bulbs or cloves was correlated with later emergence and much later flowering in addition to slight increases in number and weight of harvested bulbs.

Carbohydrate Changes of Easter Lilies during Growth in Normal and Reduced Irradiance Environments

Abstract Changes in carbohydrate types and quantities in the bulbs, stems, leaves, and buds of Easter lilies (Lilium longiflorum Thunb. ‘Nellie White’) forced under ambient or reduced irradiance conditions were investigated. Analysis by high-performance liquid chromatography (HPLC) revealed that sucrose is the dominant soluble carbohydrate in bulb tissues, with glucose, fructose, and mannose present at significantly lower concentrations. During growth of the flowering shoot, mother bulb reserves are preferentially used regardless of greenhouse irradiance. Beginning 40 days after planting, there was a steady decrease in mother bulb starch concentration until anthesis, 70 days later. Increased bulb sucrose, glucose, mannose, and fructose concentrations were correlated with the induction of starch breakdown and carbohydrate export. Under natural greenhouse irradiance conditions, daughter bulb carbohydrate reserves were not used, as starch and soluble carbohydrate concentrations remained constant. Irradiance reductions of 50% to 85% significantly reduced total carbohydrate concentration in leaves and floral buds and induced export from the daughter bulb, as evidenced by elevated levels of daughter bulb soluble carbohydrates and reductions in starch concentration. Dark-grown plants exhibited similar daughter bulb carbohydrate metabolism patterns as plants grown in full sun: starch was not hydrolyzed and soluble carbohydrates did not increase in concentration. Collectively, these results suggest 1) bulb export metabolism is characterized by elevated soluble carbohydrate concentrations, 2) there is a minimum irradiance requirement for carbohydrate export processes from the daughter bulb, and 3) reductions in greenhouse irradiance result in reduced carbohydrate levels in Easter lily leaves and flower buds.

Reduced Irradiance Affects Dry Weight Partitioning in Easter Lily

Abstract The effects of reduced irradiance on dry weight partitioning in Easter lilies was examined by forcing vernalized bulbs of Lilium longiflorum Thumb. ‘Nellie White’ during two growing seasons. Forcing commenced in a glasshouse under standard growing conditions; immediately following flower bud initiation (FBI), plants were transferred to a range of irradiance reduction treatments (0%, 20%, 50%, or 85% reduction) in the greenhouse or to complete darkness in a growth chamber. Greenhouse irradiance reduction treatments resulted in alterations in whole-plant source-sink relationships. Total plant dry weight and overall plant quality were reduced in shaded plants. The depletion rate of mother bulb dry matter was not affected by reduced irradiance, whereas daughter bulb reserve loss was increased by irradiance reduction treatments. There was no daughter bulb reserve remobilization in plants grown in complete darkness after FBI. Flower bud and open flower dry weights were progressively reduced as irradiance was reduced. With an 85% irradiance reduction, plants forced from 17.5-cm bulbs had 63% bud abortion, whereas, with 20.0-cm bulbs, only 12% of the buds aborted. Plants grown in complete darkness after FBI became etiolated, and flowers failed to open. These results demonstrate differences in the ability of various morphological regions of the bulb to respond to reductions in greenhouse irradiance. Since the daughter bulb response to reduced irradiance was relatively slow, additional remobilization of dry matter from the daughter bulb is probably of minimal benefit during short periods of reduced irradiance in commercial greenhouses.

Role of nitrogen accumulated in tulip roots during winter season

Abstract Tulip plants accumulate a large quantity of N in their roots during the winter season. In order to analyze the role of root N accumulation on the growth and bulblet production, tulip plants were hydroponically cultured and a 15N feeding experiment was carried out. All the plants were fed with a 15N labeled culture solution for 1 month during winter, and two treatments were applied thereafter: one group of plants continued to grow in a standard culture solution containing N (+N treatment), and another was cultivated in N-free medium (-N treatment). At the time of planting one planting bulb on the average contained about 30 mg of stored N, and an additional amount of 20 mg labeled N was absorbed during the 15N feedings. On January 11 immediately after 15N feeding, 51% of total N was distributed in the roots, 30% in mother bulb scales, 15% in shoots, and 3% in the basal plate, respectively. At this stage, 15N labeled N was distributed as follows: roots 77%, mother bulb scales 11%, shoots 8%, and basal plate 2%. In the roots, 63% of N was derived from absorbed N and 37% originated from the planting bulb. The N absorbed during winter remained mainly in the roots. In addition, some part of N originating from the bulb was used for root growth. As a result the N content as well as concentration in the roots significantly increased during the underground life in winter. The +N or -N treatment after 15N feeding affected appreciably the accumulation and distribution patterns of total N, the onset of senescence, and bulblet yield. Compared with the +N treatment, the plants cultured in the -N medium exhibited earlier senescence, and the yield of the daughter bulbs was lower due to the limitation of N supply after sprouting. Although the N treatment markedly affected the growth and translocation of N, the distribution pattern of 15N was basically not affected. At first 70–80% of 15N was stored in the roots until sprouting, then most of it was rapidly translocated mainly to the leaves, and finally about half of 15N was utilized for daughter bulb production in either treatment. The fate of N in the above-ground parts was essentially similar both for the N originating from the bulb and N absorbed from the roots during winter. Either N translocated mainly to the leaves after sprouting, then finally about half of N was recovered in the daughter bulbs at harvest. It was suggested that N absorbed and accumulated in the roots during the winter season may play an important role in supplementing the N originally stored in the mother bulb. In addition, the N accumulated in the roots was more rapidly and readily utilized for leaf development just after sprouting, compared with N originating from the mother bulb scales Abbreviations BN N originating from mother bulb DW dry weight FW fresh weight LN labeled N TN total N

Behavior of carbohydrates in mother and daughter bulbs of tulips (Tulipa gesneriana)

Abstract The changes in the reserve carbohydrate constituents were observed in the mother bulb scales and bulblets of tulip plants (Tulipa gesneriana) grown in a culture solution. At the time of planting, starch was the predominant reserve carbohydrate in mother bulb scales. The starch content decreased continuously until January, but starch degradation was interrupted for about 2 months until sprouting occurred. Thereafter rapid starch consumption resumed and the starch content was depleted until anthesis. The concentration of soluble carbohydrates especially the sucrose concentration in the mother bulb scales increased rapidly in winter, with maximum values of 64 mg/g FW on January 13. Regarding the changes in the fructosylsucrose content after planting, the content of isokestose (GF2) increased, and that of nystose (GF3) remained constant, while the content of pentasaccharide (GF4) and insoluble fructan with a high degree of polymerization decreased as in the case of starch. All the fructosylsucroses w...

Isolation and structure of a new organic acid accumulated in tulip plant (Tulipa gesneriand)

Abstract A large quantity of an unidentified organic acid was detected in the tulip leaves and stems. The compound was identified as 2-oxo-4-methyl-3-pentene-1,5-dioic acid mainly based on 1H- and 13C-NmR spectra. This organic acid was present in the leaves and stems at a high concentration (ca. 10% of dry weight maximum). It was also detected in the flowers and daughter bulbs, but not in the roots, mother bulb and the basal plate. The organic acid content in the stem increased after sprouting of the plant, and it rapidly decreased immediately before flowering. On the other hand, the leaves continued to accumulate the acid until the flowering stage, and the level did not decrease thereafter until harvesting.

Morpho-ecological studies on geophilic plants: Vegetative reproduction inIris vartani (Iridaceae)

Structure and behaviour of the underground organs ofIris vartani were investigated in connection with the vegetative reproduction of this species. Under favourable conditions, well developed mature plants give rise to two replacement bulbs and to several propagation bulblets each year. In spite of this considerable vegetative propagation, no crowding occurs at the natural habitat. Controlled experiments show that as soon as a small group is formed, each bulb produces only one replacement bulb and not two as before. Moreover, the bulblets do not sprout while they are attached to the respective mother bulbs, but rather die and disintegrate, remaining as empty peels. In contrast, detached bulblets, sown individually in separate pots, germinate readily. Consequently, the aggregates ofI. vartani do not increase to any great extent and thus ensure their survival “in situ” for many years.

In Vitro Propagation of Narcissus tazetta1

Abstract Regeneration of bulblets was induced in tissue culture of twin-scale bases taken from bulbs of Narcissus tazetta cv. ‘Grand Soleil d‘Or’. Bulblet formation took place in the dark, on a Murashige and Skoog (MS) medium supplemented with 30 g/liter sucrose and 5 g/liter activated charcoal (AC). Omission of AC led to a significant reduction in bulblet regeneration and growth, and addition of 1-naphthaleneacetic acid (NAA) and 6-benzylamino purine (BA), to a medium without AC, completely inhibited bulblet formation. The inhibitory effect of NAA and BA was nullified by AC. Light reduced bulblet regeneration and growth in explants cultured on an AC-containing medium. Bulblet regeneration was also induced on explants prepared by splitting culture-derived bulblets into halves and incubating them on a MS medium supplemented with sucrose and AC. Under optimal culture conditions, bulblet regeneration on twin-scale bases, combined with bulblet regeneration on split culture-derived bulblet explants, leads to the production of 200–300 bulblets from one mother bulb in about half a year. Excised bulblets developed leaves and roots when cultured in the light on half-strength MS medium supplemented with 30 g/liter sucrose and 0.1 mg/liter NAA. Fully developed plantlets could be planted out directly to the open field.

Growth regulator requirements for adventitious regeneration from Lilium bulb-scale tissue in vitro, in relation to duration of bulb storage and cultivar

Addition of NAA (1-naphthylacetic acid) to the nutrient medium strongly influenced the adventitious regeneration of plantlets from bulb-scale tissue of lilies in vitro. The percentage of regenerating explants, the number of plantlets per explant, and also the bulblet growth of the resulting plantlets were affected by the auxin, low concentrations being stimulatory and high concentrations inhibitory. The cytokinins BA (6-benzyladenine) and 2iP (N6-[Δ2-isopentenyl]-adenine) did not influence the adventitious regeneration, but caused aberrant growth of the regenerated plantlets. Prolonged cold storage of the mother bulbs decreased the demand for exogenous auxin for maximum adventitious regeneration. The optimum for bulblet growth was not affected. Results of experiments with cultivars ‘Pirate’, ‘Enchantment’ and ‘Connecticut King’ suggest an inverse relationship between the in vivo propagation rate by scaling and the NAA demand for optimal adventitious regeneration in vitro.

Growing onion seeds in an arid region: Drought tolerance and the effect of bulb weight, spacing and fertilization

The onion plant was shown to be tolerant to water stress, being able to grow and produce seed yields in arid zones with limited amounts of rainfall and without irrigation. Under these conditions, large mother bulbs and high plant density (60 cm inter-row and 10 cm intra-row spacing) gave the best results. Nitrogen was very important for the production of seed yield, but high amounts applied before planting and additional supply during the growing-season as top dressing did not have a significant effect on seed yield. Similarly, enrichment of the soil with phosphorus or potassium did not increase yield.

Growth Substances of Tulip: The Activity of Gibberellin-like Substances in Field-grown Tulips from Planting until Flowering

Summary The activity of gibberellin-like substances (GLS) was determined, using a lettuce hypocotyl bioassay, for the various bulb and plant components of tulip cv. «Apeldoorn» growing in the field in southern England. Plants were sampled at intervals from October (planting time) until the following April (flowering time). Two peaks of GLS activity were found over the course of the samples. The first of these occurred in December or early-January in most components, prior to the satisfaction of the cold requirement. In the acidic fraction there was a peak of GLS activity in the December sample in leaf and daughter bulb (DB) extracts, and in the early-January sample in extracts of the stem and mother bulb scale components; high activity was also found in the young flowers sampled in October and in the basal plate (BP) region containing actively growing root initials sampled on the same date. In the basic fraction, the peak occurred in the December samples of all components (except the outer fleshy bulb scales) preceding the main peak in the acidic fraction. In the bound fraction the peak occurred in December in the flower extracts and in early-January in root, BP, inner scale, leaf and stem extracts, but was absent in extracts of the other components. During this time, the GLS activity of the acidic, basic and bound fractions of the whole bulb increased from 83, 1 and less than 1 to 1308, 431 and 130 ng/bulb, respectively. The second peak occurred around rapid shoot extension and flower maturation (February to April samples), but there was less consistency in its date in the various plant components.