Canterbury bells (Campanula medium `Champion Blue') seeds were primed using calcined clay at 68 °F (20 °C) for 1, 3, or 5 days at water potentials (Ψ) of -25, -20, -18, or -16 bars (-2.5, -2.0, -1.8, or -1.6 MPa). Germination was fastest (3.0 to 3.1 days) after priming with a Ψ of -18 or -16 bars for 5 days. Seeds primed for 3 or 5 days with moisture present germinated faster than nonprimed seeds, but time to 50% germination (T50) was longer when seeds were primed for 1 day regardless of Ψ compared to nonprimed seed. Germination uniformity decreased (time from 10% to 90% germination, T10-90, increased) as Ψ increased. Although a curvilinear relationship existed between T10-90 and priming duration, T10-90 did not differ between nonprimed seeds and seeds in any priming treatment except those primed for 3 days with 20% moisture (-16 bars). Priming did not affect total germination percentage (97%).
Theresa L. Bosma, Janet C. Cole, Kenneth E. Conway, and John M. Dole
Vijaya Kumar Rapaka, James E. Faust, John M. Dole, and Erik S. Runkle
This study investigated the preharvest carbohydrate status and postharvest ethylene action of unrooted shoot-tip cuttings of lantana ‘Dallas Red’ harvested at three times during the day (0800, 1200, and 1600 hr) in relation to subsequent leaf abscission, shoot apices blackening, and adventitious root formation. The cuttings harvested at various times during the day were stored in darkness at 20 ± 1 °C for 4 days in sealed polyethylene bags. The cuttings harvested at 0800 hr had lowest total nonstructural carbohydrate concentrations; however, the amount of ethylene production during postharvest storage was similar among harvest times and increased during the storage period. After 4 days of storage, 69% of the leaves of cuttings harvested at 0800 hr abscised, but only 22% and 8% of the leaves abscised in cuttings harvested at 1200 and 1600 hr, respectively. Application of 1-methylcyclopropene (1-MCP) increased ethylene production and suppressed leaf abscission regardless of the harvest time, but cuttings harvested at 0800 hr developed blackened shoot apices. Leaf abscission was negatively correlated with total nonstructural carbohydrate concentration in the leaves, but no relationship was found with ethylene production. These results indicate that a high endogenous carbohydrate status decreases the postharvest ethylene sensitivity in unrooted shoot-tip cuttings of lantana. Time of harvest influenced subsequent rooting response; however, 1-MCP application did not inhibit rooting. Among various storage treatments, the best rooting response was observed in cuttings harvested at 1600 hr and treated with 1-MCP. Therefore, significant improvement of postharvest storage quality in vegetative lantana cuttings could be achieved by harvesting cuttings late in the day and treating with 1-MCP.
Kenneth E. Conway, John M. Dole, Theresa L. Bosma, and Niels O. Maness
Field seedling emergence of four african marigold (Tagetes erecta) breeding lines, A-975, E-1236, I-822, and `Orange Lady', was examined using three or four spring sowing dates and either osmotic or solid matrix priming. Delayed sowing decreased emergence time. Sowing from middle to late April [average soil temperatures 77.0 to 84.2 °F (25 to 29 °C)] resulted in the highest total emergence percentages. Greater fl ower quantities [4.9 to 5.1 million/acre (12.11 to 12.60 million/ha)] and estimated yield [7.5 to 10.8 tons/acre (16.81 to 24.20 t·ha-1)] indicate mid to late April is the optimum time period for direct sowing unprimed seed in the southern Great Plains. Differences between lines were evident in emergence parameters and fl ower harvest data for each year examined, but results were inconsistent from year to year. However, A-975 and E-1236 produced harvestable fl owers most quickly, about 15 d before I-822, which could result in an additional harvest during a season. Osmotic priming of E-1236 and I-822 seed shortened emergence time, increased emergence uniformity, and increased total emergence percentage at early sowing dates as compared to both solid matrix primed and unprimed seed.
Iftikhar Ahmad, Muhammad B. Rafiq, John M. Dole, Bilal Abdullah, and Kinza Habib
Favorable agro-climatic conditions and comparatively cheaper and readily available human resources offer a promising business opportunity to cut flower production in Pakistan. Presently, growers are limited to traditional cut flower crops such as rose (Rosa hybrids), gladiolus (Gladiolus hybrids), marigold (Tagetes erecta), and tuberose (Polianthes tuberosa) because of unavailability of improved new species and cultivars. To diversify cut flower production in Pakistan, a study was conducted to evaluate the production and postharvest performance of different cultivars of delphinium (Delphinium hybrids), snapdragon (Antirrhinum majus), and stock (Matthiola incana) in Faisalabad, Punjab, Pakistan. ‘Guardian White’ delphinium had the shortest time to harvest first marketable stems (160 days) with comparatively shorter stems (87.7 cm). Whereas ‘Aurora White’ and ‘Aurora Blue’ were high-temperature tolerant and produced attractive racemes with longer stems; 112.0 and 99.7 cm, respectively. All cultivars lasted about 7 days in distilled water (DW). ‘Cheerful White’ stock had the shortest cropping time and produced highest quality double flowers with longest stems (51.8 cm) compared with other cultivars tested. Vase solution of 4% sucrose supplemented with 100 mg·L−1 silver nitrate (AgNO3) extended the vase life of ‘Cheerful White’ stock up to 11.8 days compared with 8.2 days in DW. Pulsing with 10% sucrose supplemented with 100 mg·L−1 AgNO3 extended the longevity of ‘Lucinda Dark Rose Double’ stock (10.2 days) similar to vase solution of 4% sucrose plus 100 mg·L−1 AgNO3; however, ‘Lucinda Dark Rose Double’ stock produced shorter stems than ‘Cheerful White’. ‘Appleblossom’ snapdragon produced >10 marketable stems per plant with highest quality attractive flowers, and stout stems, which lasted 10.8 days in 4% sucrose vase solution supplemented with 100 mg·L−1 AgNO3. Among tested species/cultivars, all exotic species/cultivars produced uniform high quality stems resulting in higher productivity as compared with local cultivars and were favorably appraised by flower growers/retailers and are best suited for diversification of local cut flower industry.
Brian A. Krug, Brian E. Whipker, Ingram McCall, and John M. Dole
Preplant bulb soaks of ancymidol, flurprimidol, paclobutrazol, and uniconazole; foliar sprays of flurprimidol; and substrate drenches of flurprimidol, paclobutrazol, and uniconazole were compared for height control of `Prominence' tulips (Tulipa sp.). Height control was evaluated at anthesis in the greenhouse and 10 days later under postharvest conditions. Substrate drenches of ancymidol, flurprimidol, and paclobutrazol resulted in adequate control using concentrations of 0.5, 0.5, and 1 mg/pot a.i. (28,350 mg = 1 oz), respectively. At these concentrations, ancymidol drenches cost $0.06/pot and paclobutrazol drenches $0.03/pot. Since flurprimidol is not yet available and no price is available, growers will need to assess the cost compared to ancymidol and paclobutrazol. Flurprimidol foliar sprays at <80 mg·L–1 (ppm) were ineffective in controlling height during greenhouse forcing, but during postharvest evaluation 80 mg·L–1 resulted in 14% shorter plants than the untreated control. Preplant bulb soaks of flurprimidol, paclobutrazol, and uniconazole at concentrations of 25, 50, and 10 mg·L–1, respectively, effectively controlled plant height. Preplant plant growth regulator soaks are a cost-effective method of controlling plant height of tulips because of the limited amount of chemical required to treat a large quantity of bulbs.
Erin M.R. Clark, John M. Dole, Alicain S. Carlson, Erin P. Moody, Ingram F. McCall, Frankie L. Fanelli, and William C. Fonteno
Each year a wide variety of new cultivars and species are evaluated in the National Cut Flower Trial Programs administered by North Carolina State University and the Association of Specialty Cut Flower Growers. Stems of promising and productive cultivars from the National Trial Program were pretreated with either a commercial hydrating solution or deionized (DI) water and placed in either a commercial holding solution or DI water. Over 8 years, the vase life of 121 cultivars representing 47 cut flower genera was determined. Although there was cultivar variation within each genus, patterns of postharvest responses have emerged. The largest category, with 53 cultivars, was one in which a holding preservative increased vase life of the following genera and species: acidanthera (Gladiolus murielae), basil (Ocimum basilicum), bee balm (Monarda hybrid), black-eyed susan (Rudbeckia hybrids), campanula (Campanula species), celosia (Celosia argentea), common ninebark (Physocarpus opulifolius), coneflower (Echinacea purpurea), coral bells (Heuchera hybrids), feverfew (Tanacetum parthenium), foxglove (Digitalis purpurea), ladybells (Adenophora hybrid), lisianthus (Eustoma grandiflorum), lobelia (Lobelia hybrids), obedient plant (Physostegia virginiana), ornamental pepper (Capsicum annuum), pincushion flower (Scabiosa atropurpurea), pinkflower (Indigofera amblyantha), seven-sons flower (Heptacodium miconioides), shasta daisy (Leucanthemum superbum), sunflower (Helianthus annuus), snapdragon (Antirrhinum majus), sweet william (Dianthus hybrids), trachelium (Trachelium caeruleum), and zinnia (Zinnia elegans). Hydrating preservatives increased the vase life of four basils, coral bells, and sunflower cultivars. The combined use of hydrator and holding preservatives increased the vase life of three black-eyed susan, seven-sons flower, and sunflower cultivars. Holding preservatives reduced the vase life of 14 cultivars of the following genera and species: ageratum (Ageratum houstonianum), false queen anne's lace (Ammi species), knotweed (Persicaria hybrid), lisianthus, pineapple lily (Eucomis comosa), sneezeweed (Helenium autumnale), yarrow (Achillea millifolium), and zinnia. Hydrating preservatives reduced the vase life of 18 cultivars of the following genera and species: feverfew, lisianthus, ornamental pepper, pineapple lily, seven-sons flower, shasta daisy, sneezeweed, sweet william, sunflower, trachelium, yarrow, and zinnia. The combined use of hydrating and holding preservatives reduced the vase life of 12 cultivars in the following genera and species: false queen anne's lace, feverfew, pincushion flower, sneezeweed, sunflower, trachelium, yarrow, and zinnia. Data for the remaining 50 cultivars were not significant among the treatments; these genera and species included beautyberry (Callicarpa americana), black-eyed susan, blue mist (Caryopteris clandonensis), calendula (Calendula officinalis), campanula, cleome (Cleome hasserliana), common ninebark, dahlia (Dahlia hybrids), delphinium (Delphinium hybrids), flowering peach (Prunus persica forma versicolor), heliopsis (Heliopsis helianthoides), hemp agrimony (Eupatorium cannabinum), himalayan honeysuckle (Leycesteria formosa), hydrangea (Hydrangea paniculata), larkspur (Consolida hybrids), lily of the nile (Agapanthus hybrid), lisianthus, lobelia, ornamental pepper, pineapple lily, scented geranium (Pelargonium hybrid), sunflower, sweet william, and zinnia.