Easter Lily Research Articles

Postharvest Treatment of Easter Lily Bulbs Prior to Shipping

Easter lily bulbs are harvested in fields in northern California and southern Oregon, packed in cases, and shipped to distributors and growers. The greenhouse forcer then cools the bulbs at 40–45°F for 6 weeks. This cold period is needed to vernalize the bulbs and to assure that the plants will later flower uniformly. Bulbs that have been cooled for longer or shorter lengths of time respond differently. The objective of this study was to determine the optimal storage temperature regime for the bulbs dug during the early part of the 3-week bulb-harvest period. Twelve groups of bulbs at various storage temperature regimes were evaluated as to their performance during greenhouse forcing. The variables that were considered were: 1) bud count, 2) variability of flowering date, 3) earliness of flowering date, 4) variability of Visible Bud date, and 5) variability of final plant height. An index was developed to evaluate the degree to which each variable impacted the production during the forcing phase. We found that the best protocol for bulb growers is to dig the bulbs and then hold them at cool (>45°F) ambient temperatures for a week. Temperatures higher than the high 65°F should be avoided. If the bulbs will be stored just 1 more week, then they can stay at this temperature; otherwise, the bulbs should be cooled down to, and held at, 42 to 45°F.

Increase of Easter Lily Postharvest Flower Longevity with PBA Application to Young Flower Buds

Case-cooled bulbs of Lilium longiflorum `Nellie White' were potted on 4 Dec. 1995 and forced to flowering using standard growing procedures. Plants were illuminated from shoot emergence to visible bud with supplemental high-intensity-discharge sodium vapor light at 70 μmol·m–2·s–1 from 1700 to 2200 HR each day. When the first primary flower bud (first initiated flower bud most proximal on the shoot) was 5 to 7 cm long, each plant was treated with 3 ml of either de-ionized water or 500 mg·liter–1 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA). Sprays were directed at the flower buds and associated bracts. When the tepals on the first primary flower bud split, plants were placed at 2°C in the dark for 0, 4, or 21 days. After storage, plants were placed in a postharvest evaluation room with constant 21°C temperature and 18 μmol·m–2·s–1 cool-white fluorescent light. The first three primary flowers on PBA-treated plants lasted significantly longer than corresponding flowers on control plants, but there was no difference between flowers at the fourth and fifth positions. Also, the total postharvest life of the five primary flowers on PBA treated plants was 3 days longer than those on control plants. Storage time inversely affected the postharvest longevity of the first three primary flowers, but had no effect on the longevity of the fourth or fifth primary flowers or total postharvest life of the five primary flowers. There were no significant interaction effects between PBA treatment and storage duration on primary flower longevity.

A decision-support system for real-time management of Easter lily ( Lilium longiflorum Thunb.) scheduling and height—II. Validation

Computer decision-support systems (DSS) are interactive programs that provide model recommendations in a problem area. An experiment was conducted to validate a DSS for scheduling and height control of Easter lily ( Lilium longiflorum Thunb.) called The Greenhouse CARE System. The DSS was used to recommend temperature settings in three locations (Michigan, California and Denmark) with the goal of producing Easter lilies to predefined flowering and visible bud dates, and to plant height targets. Day and night temperature settings recommended by the DSS were the sole method used to control timing and, secondarily, plant height. Flowering of 50% of plants occurred on the specific target date in two locations and was one day early in the third location. The DSS was less able to achieve a target visible bud date, and information from commercial crops grown with the DSS indicated changes needed to implement a leaf unfolding rate model. Plant height was consistently taller than desired, indicating that growth retardants need to be included in future model recommendations. DSS temperature recommendations were similar to those made by experienced Easter lily producers.

A decision-support system for real-time management of Easter lily ( Lilium longiflorum Thunb.) scheduling and height—I. System description

A decision-support system was developed for recommending night and day temperature settings to control the timing and height of Easter lily ( Lilium longiflorum Thunb.). Existing biological models and qualitative rules were combined into an overall model of the response of plant development rate to temperature. A process control algorithm was used to determine appropriate height control actions based on a graphical control chart of plant height over time. A knowledge-based system checked the feasibility of output from the development and height control models and generated a text report. This model was implemented on a personal computer in a program called “The Greenhouse CARE System” and has been linked directly with an environmental computer to control greenhouse temperatures. A companion article describes validation of this model.

Respiratory Changes Associated with Growth-regulator-delayed Leaf Yellowing in Easter Lily

Senescence of excised Easter lily leaves is typically marked by a rise in respiration without a concomitant production of ethylene. Treating excised leaves with 500 mg·L-1 of gibberellic acid (GA3) or benzyladenine (BA) significantly delayed the onset of leaf yellowing, lowered the respiration rates by one-third to one-half, and markedly delayed the respiratory rise. Similar effects on respiration were detected in leaves treated with BA or GA3 before a 4-week period of cold storage and in leaves treated after chlorosis had initiated. Results of this study indicate that excised Easter lily leaves respond to the growth regulators with a significant decrease in respiration rate.

ENHANCEMENT OF POSTPRODUCTION QUALITY OF EASTER LILY BY GROWTH REGULATORS

The development of postproduction foliar chlorosis is one of the critical problems that remains unsolved in Easter lily production. Plants at the white puffy stage were sprayed with 500 mg gibberellic acid (GA3)/liter, 500 mg benzyladenine (BA)/liter, 500 mg each GA3 and BA/liter, 500 mg ProGibb (containing 500 mg GA3/liter)/liter, and 1000 mg Promalin (containing 500 mg GA4 + GA7/liter and 500 mg BA/liter)/liter, and a water control. Development of foliar chlorosis was evaluated in a simulated interior environment at a temperature of 22.6 ± 0.2C and illuminated 12 h·d–1 with 11.2 ± 0.1 mmol·m–2·s–1 from cool-white fluorescent lamps. Results demonstrated that GA3, BA, ProGibb, and Promalin are effective in delaying the development of foliar chlorosis of cold-stored plants. Promalin was the most effective. Concentrations of Promalin as low as 50 mg· liter–1 were effective. Treatments had no effect on the development and the longevity of flower buds. This study thus suggests that application of Promalin to Easter lily plants prior to marketing is a viable solution to preventing postproduction development of foliar chlorosis.

Cytokinin and Light Intensity Regulate Flowering of Easter Lily

Lilium longiflorum Thunb. `Nellie White' plants were selected when their first flower buds reached 2 or 5 cm in length, sprayed with 2 mL of PBA at 0 or 500 mg·L–1, and then placed under 1440 or 60 μmol·m–2·s–1 photosynthetic photon flux (PPF) during flowering. PBA resulted in delayed anthesis and increased dry matter accumulation in flowers under the high PPF but had no effect under the low PPF. PBA did not decrease the severity of flower bud abortion under the low PPF. Application of PBA induced the formation of numerous bulbils in the leaf axils. Regardless of PPF, PBA-treated plants had less dry weight in the main bulbs than the control plants. Chemical name used: N-(phenylmethyl)-9-(tetra-hydro-2H-pyran-2-yl)-9H-purin-6-amine (PBA).

Control of Leaf Senescence of Easter Lily using Plant Spacing and Early Applications of Promalin

Easter lilies (Lilium longiflorum Thunb. `Nellie White') were placed at three spacings of about 11, 22, or 44 plants per square meter (plants/m2). Above canopy light intensities, measured weekly at noon, ranged from 107.3 to 704.5 μmol·s–1·m–2 and were not significantly different among spacings. Mid canopy light intensities ranged from 16.5 to 229.0, 43.0 to 458.5, and 77.5 to 535.3 μmol·s–1·m–2 at spacings of 44, 22 and 11 plants/m2, respectively. On February 5, 1996, three plants from the 22 plants/m2 spacing were sprayed with a solution of 0.5 ml·L–1 of 1.8% (a.i.) of each of N-(phenylmethyl)-IH-purine-6-amine and gibberellins A4A7; and on March 5, three additional plants from each spacing were similarly sprayed. Beginning 5 Mar., weekly counts were made of yellow and brown leaves on all treated and control plants. Average per plant numbers of brown leaves increased on control plants at all spacings but increased on treated plants only at the 11 plants/m2 spacing. On 25 Mar., control plants averaged 15.6, 12.1, and 15.3 brown leaves per plant at spacings of 11, 22, and 44 plants/m2, respectively, while plants treated on March 5 averaged 10.7, 9.0, and 10.7 brown leaves. Plants treated on 5 Feb. averaged 3.5 brown leaves per plant and had an average mid leaf length of 13.8 cm compared to about 10.5 cm for all other plants. Spacing had no effect on average yellow or brown leaves per plant. This study demonstrated that early applications of Promalin can reduce leaf senescence which may occur during forcing time before bud appearance to opening of first bud. Some leaf enlargement may occur on plants treated very early.

GA4+7 Plus Benzyladenine Reduce Leaf Yellowing of Greenhouse Easter Lillies

Chlorosis of Easter lily (Lilium longiflorum) lower leaves causes significant economic loss. Lily plants growing in 15-cm pots were sprayed 30, 60, or 90 days after emergence or at 60 and 90 days after emergence with 25 to 100 ppm each of benzyladenine and GA4+7 from Promalin (Abbott Chemical Co.) and were grown pot-to-pot until flower. Chlorotic leaf count at flower decreased as Promalin concentration increased; plants sprayed at 60 days had the smallest chlorotic leaf count. Chlorotic leaves at flower varied from 28% for control plants to 10% for plants sprayed with 100 ppm at 60 days and from 36% to 17% 3 weeks later, respectively. The Promalin sprays promoted significant stem elongation, but differences in height at flower were only 2 cm. Plants sprayed with 100 ppm at 30 days averaged one deformed flower per plant; plants sprayed at 60 days and 60 and 90 days averaged 0.0 and 0.1 deformed flower per plant, respectively. Additional trials in which only the lower part of the plant was sprayed prevented any chlorotic leaves without any significant effect on final height or flower bud quality.

Modeling Flower Bud Elongation in Easter Lily (Lilium longiflorum Thunb.) in Response to Temperature

A model was developed to quantify the response of Easter lily (`Nellie White') flower bud elongation to average air temperature. Plants were grown in greenhouses set at 15, 18, 21, 24, or 27C after they had reached the visible bud stage. An exponential model fit the data with an R2 of 0.996. The number of days until open flowering could be predicted using the model because buds consistently opened when they were 16 cm long. The model was validated against data sets of plants grown under constant and varying greenhouse temperatures at three locations, and it was more accurate and mathematically simpler than a previous bud elongation model. Bud length can be used by lily growers to predict the average temperature required to achieve a target flowering date, or the flowering date at a given average temperature. The model can be implemented in a computer decision-support system or in a tool termed a bud development meter.

A Graphical Control Chart for Monitoring Leaf count of Easter Lily to Support Crop Timing Decisions

A graphical control chart was developed to monitor leaf count of Easter lily (Lilium longiflorum Thunb.) and make temperature recommendations based on predictions of a leaf unfolding rate (LUR) model. The graph allows observed and target leaf count to be compared visually over time. Timing of the visible bud stage, when flower buds are visible externally on the plant, is important to time flowering for the Easter sales period. The optimum LUR and average daily temperature required to achieve a target visible bud date can be read directly from the chart. The approach provides an intuitive method for transferring quantitative models to growers.

Far-red at End of Day and Reduced Irradiance Affect Plant Height of Easter and Asiatic Hybrid Lilies

Potted bulbs of Lilium longiflorum Thunb. `Ace' and `Nellie White' and Lilium (Asiatic hybrid) `Enchantment' were grown in a greenhouse under ambient photoperiod (APP), 8-h photoperiod by removing twilight from ambient by blackout cloth (8PP), or 8PP extended with 1 hour of low-intensity far-red radiation (9PP). Height of `Ace', `Nellie White', and `Enchantment' increased by 24%, 18%, and 12%, respectively, under APP and by 118%, 100%, and 44%, respectively, under 9PP compared to 8PP. In a second experiment, the effects of reduced irradiance (0%, 25%, 50%, and 75% shade) were determined on the same cultivars grown under APP or 8PP. The effects of APP on height were similar in magnitude for `Ace' and `Nellie White' but were insignificant for `Enchantment' compared to 8PP. Shading increased height linearly for all cultivars. The regression was greater under APP (2.8 mm/percent shade) than under 8PP (1.8 mm/percent shade) for `Ace' and `Nellie White' combined. Plant height of `Enchantment' was less affected by reduced irradiance. For all cultivars, APP or 9PP produced higher stem dry weight compared to 8PP. Shading decreased leaf and bulb dry weight of the Easter lily cultivars.

Leaf Petiole NO3-N and K Analysis for Greenhouse-grown Flowering Potted and Bedding Plants

Unlike vegetable and fruit crops, where petiole analysis has been used for many years, root media analysis is the primary method of checking fertility status of container-grown flowering greenhouse crops. With the emphasis on lower constant water-soluble fertilizer rates to prevent nutrient runoff, petiole analysis may be a better indicator of N and K status. During Fall 1993, samples were collected from 10 flowering pot plant species subirrigated with either 50, 100, or 200 mg·liter–1 N and K concentrations. During Spring 1995, samples were collected from major bedding plant species and Easter lilies. Sap was extracted using a hydraulic press and nitrate and potassium were measured with the Cardy flat electrode ion meters. Sampling methods and protocols will be presented with results of sampling technique experiments. Floriculture plant nutrition researchers were contacted to identify other research in progress, potential applications, and possible concerns with using this technique. Further research needed will be identified.

Variation of Chromosome Numbers in Easter Lily Regenerated from Ovary Tissues

Easter lily (Lilium longiflorum L.) cultivars Ace and Nellie White were regenerated through the culture of immature ovary tissues. Shoot initiation and proliferation were most efficient when a modified Murashige and Skoog (MS) medium containing 5% sucrose, 1 mg 2,4-D/liter, and 2 mg benzylamino purine (BAP)/liter was used. The shoots, when divided and subcultured on the same medium, formed roots within 4 weeks. The rooted plants were transferred to soil in a greenhouse. Root-tip smears made from the regenerated plants showed a range of variation in chromosome numbers from 10 to 25 per cell, in contrast to the bulb-grown plants, which had 2x = 24 chromosomes per cell. The mixoploid condition existed in many regenerants exhibiting chromosome number variation in different root cells of the same plant.

Graphical Tracking Leaf Count to Support Easter Lily Crop Timing Decisions

Timing of Easter lily (Lilium longiflorum Thunb.) for sales is complex because the date of Easter and the number of leaves formed on plants before flower bud initiation vary from year to year. A process control chart was developed that uses a leaf unfolding rate model of Easter lily to control development rate towards flowering. The technique allows observed and target leaf count to be tracked on a graph and compared visually over time. The optimum leaf unfolding rate and average temperature can be read directly from the chart without the need for mathematical calculation. The approach provides an intuitive method for transferring quantitative models to growers and can be applied to other management problem areas.

PHYSIOLOGICAL CHANGES ASSOCIATED WITH LEAF SENESCENCE IN EASTER LILIES

Senescence of lower leaves of Easter lilies (Lilium longiflorum Thunb.) was previously shown to be delayed with application of the growth regulators, gibberellic acid (GA3) and benzyladenine (BA). This study was done to determine the physiological effects of GA3 and BA in relation to the delay of leaf senescence. Foliar application with 500 ppm BA or GA3 delayed chlorosis and lowered respiration rate in Easter lily leaves. A combination of 500 ppm BA and 500 ppm GA3 was more effective than the individual application of each. Gibberellic acid, BA, or their combination before cold storage resulted in delayed chlorosis and lowered respiration following removal from cold storage. Treatment with growth regulators after cold storage was less effective. Senescence of leaves was not associated with ethylene since ethylene production by leaves was undetectable by gas chromatograph. In addition, pulsing or continuous treatment with silver thiosulphate (STS), an inhibitor of ethylene synthesis, did not delay foliar chlorosis. Analysis of carbohydrate levels in Easter lily leaves treated with GA3, BA, or their combination may contribute to the understanding of the physiological effects of these two growth regulators.

PERFORMANCE OF `NELLIE WHITE' EASTER LILIES IN ROOT MEDIA CONTAINING COAL BOTTOM ASH

Easter lilies (Lilium longiflorum Thunb. `Nellie White') were forced in root media composed of 1 peat: 1 vermiculite (v/v) mixed with coal bottom ash (CBA) at rates of 0%, 25%, 50%, 75%, or 100% CBA. Lilies in all levels of CBA were equal in mean per plant flower bud numbers, fresh and dry weights, and numbers of yellow or brown lower stem leaves. Lilies in 100% CBA were significantly lower in mean stem length than plants in 0% or 50% CBA. Plants in 100% CBA required more frequent irrigation than plants in all other media. Media pH and solution electrical conductivity increased with increase in percent CBA. Analysis of leaf tissue showed no difference in nutrient levels between plants in 0% or 100% CBA.

Class Picture, My Grandmother as Teacher, 1922, and: Beldora Burrell, and: Leda, and: Simple Arithmetic, and: Esther S.

CLASS PICTURE, MY GRANDMOTHER AS TEACHER, 1922 / Kathleen McGookey No knowing what she knows, no small, sad smile, just a steady gaze, her hands carefully placed on the arms of the wicker chair. Absolutely still for minutes the photographer clicked and muttered and fussed. She gazes out of the chair. She sees the first snow falling, dizzy patterns, and the big eighth-grade boys—she's afraid of them—running past. This day of expectation, a carriage ride, a white rabbit muff, and a certain dignity lost, a word, once said, that cannot be called back. Each time smoke rises from the black stove, she claps the lid down, then returns to the front of the classroom, something like fear in the back of her throat. Her hair smoothed back with a big navy bow. Some children she loves less than herself, and the boys would be better off in the fields, far from her, better caught in moonlight in hay, not half tamed in class, bodies spilling off their chairs. Her hair is smoke, the smoke that rose as her father's barn burned, and eight men on horseback formed a half circle around the blaze and simply watched. Slow music and tall buildings rise in her mind. She'd rather the photographer gone, the children too, and the books expectant in the empty room. 86 · The Missouri Review BELDORA BURRELL / Kathleen McGookey Five women, my five sisters, sit in court with Easter lilies on their laps. No one here watches me so I watch them. As a rule, we don't have such beautiful sunshine, but I have grief large as a body inside me, or its simple beginnings, the way white lilacs and lilies of the valley make me ache, how finally their absence is heartbreak, a rippled reflection on a platter: not the reflection silvering itself, but unexpected, it isn't real. To begin with, begin with then: the linen tablecloth to hem, the black car shining in the garage. The bed and the desk and the budget, and the queer leap just thinking it all. There was a clapboard house, a brother-in-law, and trips to Indiana with more canned chicken and jelly jars than I could count. The heart isn't the center of the body, but it's better if it isn't told. This is forward motion, I know, though it feels nothing like it. I've dyed my white silk uniform a dull dark red, so those people who talk will think of a mouth, a ruby red yard, the bloody hours filling a clock, so I can fall into calla lilies, and poinsettias tall as one-story houses to balance the bearable pleasures of living. The Missouri Review · 87 LEDA / Kathleen McGookey Still alone, holding her breath and watching night fall like in a Magritte painting: trees outlined in black and a thumbnail moon carved in inky-blue sky. Under water, fish see this gold moon, each wave with its own piece of sky, and six swans: two white, four grey. All the plums fallen from her trees, the fire died and weather very nearly out of control. Her arms clean and white and beginning to be strong. The six swans not her obsession, yet appeared daily. Her face grew pale: she would not wish another swan into a man. To begin with, she said, hands weren't worth waiting for. Then the problem of too much light; afterwards, the lake began to freeze, hundreds of black Canadian geese honked on ice, and the swans circled in smaller and smaller patterns. She let go of their silhouettes, of the silhouette of desire, of falling into the perfect temporary quiet of a mouth. The swans like angels, like god, like bodies on the sidewalk not quite covered by sheets. No comfort in wings: even a tulip's slight curve is obscene in wrong hands, even roads curving, trees leaning in strong winds, even that is wrong. Her hands smelled of garlic. Bonfires glowed and smoke hung in the trees. She waited to be lifted out of her body as she stood at the sink, dishes steaming. Already she saw broken...

A practical method for the production of flowering Easter lilies from callus cultures

Callus cultures were established from immature leaf explants of Easter lily ( Lilium longiflorum Thunb. cv. ‘Nellie White’). These callus cultures were induced to undergo organogenesis within 3 weeks upon subculture to medium containing 0.1 mg l −1 of both 2,4-dichlorophenoxyacetic acid and 6-benzylaminopurine. The regenerated plantlets were acclimatized under a mist and transferred to greenhouse conditions at a 100% success rate. Plants exposed to supplemental lighting produced an average of four flowers per plant, were 20 cm shorter and flowered six and a half weeks sooner than plants maintained under normal day length conditions, where only 63% of the plants flowered. On average, plants supplied with supplemental lighting required 29 weeks (8 weeks of acclimation, 9 weeks in 15 cm pots under normal greenhouse conditions, and 12 weeks under supplemental lighting) from the time of establishing in the greenhouse to full bloom. The number of abnormal plants observed was less than 2%. Maintaining plants in 6 cm × 4 cm × 5.5 cm growing trays produced miniature Easter lily plants, each with a single flower.

Fact and Symbol: Reflections about Easter Lilies, Religion, and Education

The further north one travels in Maine, the more mercurial the weather. This especially is true during the fall and spring (a.k.a. mud season). The air will be nippy, frost covering the pinelands, and it will seem as though, depending on the time of year, either winter is about to make its debut, or it yet has a tad more bellowing to do before it goes on holiday. But then, suddenly, the weather changes completely, and everything is warm: the temperature rises quickly, the landscape is aglow with the sun and warmth, and Down East becomes genial and toasty, defying winter's intentions.