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- Author or Editor: John M. Dole x
The purple velvet plant (Gynura aurantiaca) has commercial potential as a potted plant due to its attractive purple foliage, if the malodorous flowers can be avoided. Plants were treated with seven concentrations of ethephon, three photoperiodic durations, three light intensities, and combinations of photoperiod and light intensity to inhibit flowering. Although foliar application of ethephon at 1200 to 4800 ppm (μL·L-1) completely inhibited flowering of purple velvet plants, plants were stunted and cutting harvest was impossible. Flowering was promoted at lower application rates of 150 to 300 ppm (μL·L-1). An 8-hour photoperiod increased plant quality and plants had the largest vegetative shoot number and the brightest purple color, compared to 12 or 16-hour photoperiods. All of the shoots were reproductive under the 16-hour photoperiod. Increasing the shade level from 0 to 60% (790 μmol·m-2·s-1 to 230 μmol·m-2·s-1) increased the number of vegetative shoots at 74 and 108 days after treatment commenced but reduced the total number of shoots by 28% at day 108. Plants grown under60% shade and short days had 94% vegetative shoots 102 days after placement in treatment. Growing plants under 8-hour photoperiod and 60% shade from fall to spring is recommended to maintain vegetative stock plants and produce high quality marketable plants. Chemical names used: (2-chloroethyl) phosphonic acid (ethephon).
Poinsettias (Euphorbia pulcherrima 'Gutbier V-14 Glory'), chrysanthemums (Dendranthema grandiflora 'Tara') and geraniums (Pelargonium xhortorum 'Orbit') were grown using various ratios of controlled release:constant liquid fertilization as a percentage of recommended rates (%CRF:%CLF). While plants grown under the 100:0 CRF:CLF regime produced significantly less nitrates, phosphates and total soluble salts in the leachate than 0:100 or 50:50 CRF:CLF, quality rating, plant diameter, and leaf, bract and flower dry weight of poinsettias and chrysanthemums were reduced. Geraniums grown under 100:0, 50:50 or 0:100 CRF:CLF regimes were similar in quality rating, height, diameter, dry weights and days to anthesis. Poinsettias and chrysanthemums grown under 50:50 CRF:CLF were similar in height, days to anthesis, plant diameter, flower and stem dry weights and quality rating but produced less nitrates, phosphates and total soluble salts in the leachate than plants grown under 0:100 CRF:CLF. However, chrysanthemums grown under 50:50 CRF:CLF had lower leaf and root dry weights and poinsettias had lower leaf and bract dry weights than under 0:100 CRF:CLF regime.
Improving the quality of water released from containerized production nurseries and greenhouse operations is an increasing concern in many areas of the United States. The potential pollution threat to our ground and potable water reservoirs via the horticultural industry needs to receive attention from growers and researchers alike. `Orbit Red' geraniums were grown in 3:1 peat:perlite medium with microtube irrigation to study the effect of fertilizer source on geranium growth, micronutrient leaching, and nutrient distribution. Manufacturer's recommended rates of controlled-release (CRF) and water-soluble fertilizers (WSF) were used to fulfill the micronutrient requirement of the plants. Minimal differences in all growth parameters measured between WSF and CRF were determined. A greater percentage of Fe was leached from the WSF than CRF. In contrast, CRF had a greater percentage of Mn leached from the system than WRF during the experiment. Also, regardless of treatment, the upper and middle regions of the growing medium had a higher nutrient concentration than the lower region of medium.
The effect of cold on germination rate, percentage and range of five cut flowers was investigated: Baptisia australis (Wild Blue Indigo), Echinacea purpurea (Purple Coneflower), Helianthus maximilianii (Maximillian Sunflower), Solidago petiolaris (Spike Goldenrod), and Vernonia missurica (lronweed). Viability was determined for the species using TTC staining and germination based on percent viable seed. Seeds were given 0, 2, 4, 6, 8, or 10 weeks of cold at 5°C. Increasing weeks of cold decreased days to germination in all five species, with Baptisia demonstrating the greatest effect. The germination percent increased as weeks of cold increased in all five species, but was most significant in Helianthus and Vernonia. Days from first to last germinating seed was significantly decreased in all five species as weeks of cold increased. Four weeks of cold was optimum for Echinacea and Vernonia, while optimum weeks of cold for Helianthus and Solidago was six weeks and Baptisia ten weeks.
Pelargonium ×hortorum Bailey `Pinto Red' plants were fertilized with equal amounts of N, P, and K derived from: 1) 100% constant liquid fertilization (CLF); 2) 50% CLF plus 50% controlled-release fertilizer (CRF); or 3) 100% CRF per pot and irrigated using hand (HD), microtube (MT), ebb-and-flow (EF), or capillary mat (CM) irrigation systems. The treatment receiving 100% CRF produced greater total dry weights, and released lower concentrations of NO3-N, NH4-N, and PO4-P in the run-off than the 100% CLF treatment. The percentage of N lost as run-off was greatly reduced with the use of CRF. MT irrigation produced the greatest plant growth and HD irrigation produced the least. The EF system was the most water efficient, with only 4.7% of water lost as run-off. Combining the water-efficient EF system with the nutrient-efficient CRF produced the greatest percentage of N retained by plants and medium (90.7) and the lowest percentage of N lost in the run-off (1.7).
Days from sowing to anthesis were significantly different among six sunflower (Helianthus annuus L.) cultivars and ranged from 52 days for `Big Smile' to 87 days for `Pacino'. Height ranged from 13.5 cm for `Big Smile' to 37.3 cm for `Pacino'. Postproduction life ranged from 10 days for `Pacino' and `Elf' to 15 days for `Big Smile'. Postproduction quality ratings (1 to 5, with 5 the best) ranged from 3.9 to 5 after 5 days and 1 to 4.2 after 10 days. Quality ratings after 15 days were not significantly different among cultivars, because few plants were marketable at 15 days. Increasing the number of plants per pot from one to three or five reduced number of days to anthesis and postproduction life. Pot sizes of 10-, 13-, or 15-cm diameter, had no influence on production or postproduction characteristics. Promalin (62.5 to 500.0 mg·L–1) was not commercially useful in extending postproduction life. Two cultivars were found to be most suitable for pot production, `Pacino' and `Teddy Bear', with one plant per 15-cm pot and sprayed with B-Nine at 8000 mg·L–1.
Ethephon [(2-chloroethyl) phosphonic acid] is used to increase stock plant cutting productivity through increased flower and flower bud abscission and branching. However, ethylene evolution resulting from ethephon application is suspected to cause leaf abscission of unrooted cuttings during shipping. It was the objective of this study to assess ethylene evolution from ethephon-treated cuttings during storage and shipping of unrooted cuttings. Impatiens hawkeri W. Bull ‘Sonic Red’ and ‘Sonic White’ stock plants were treated with 0, 250, 500, or 1000 mg·L−1 ethephon. Cuttings were harvested from 1 to 21 days later and each harvest was stored at 20 °C in sealed jars for 24 h before ethylene measurement. Higher ethephon doses resulted in greater ethylene generation. Cuttings harvested 1 day after treatment with 0, 250, 500, or 1000 mg·L−1 ethephon evolved 0.07, 1.3, 1.7, or 5.8 μL·L−1·g−1 (fresh weight) ethylene in the first 24 h of storage at 20 °C, respectively. Twenty-one days after treatment, cuttings from the same plants evolved 0.05, 0.05, 0.15, or 0.14 μL·L−1·g−1 (fresh weight) ethylene in the first 24 h of storage at 20 °C, respectively. As cuttings were harvested from Day 1 to Day 21, ethylene concentrations evolved within the first 24 h of storage decreased exponentially. Rinsing cuttings, treated 24 h earlier with 500 mg·L−1 ethephon, by gently agitating for 10 s in deionized water reduced ethylene evolution to 0.7 μL·L−1·g−1 (fresh weight) as compared with 1.7 for unrinsed cuttings. Cuttings harvested 24 h after treatment with 500 mg·L−1 ethephon stored at 10, 15, 20, and 25 °C for 24 h evolved 0.37, 0.81, 2.03, and 3.55 μL·L−1·g−1 (fresh weight) ethylene. The resulting mean temperature coefficient (Q10) for the 10 to 25 °C range from all replications was 5.15 ± 0.85. Thus, ethylene continues to evolve from ethephon-treated Impatiens hawkeri stock plants for up to 21 days and can accumulate to high concentrations during cutting storage.
Rooted cuttings of four woody cut species, Buddleia davidii `Black Knight' (butterfly bush), Forsythia × intermedia `Lynwood Gold', Salix chaenomeloides (Japanese pussywillow), and Salix matsudana `Tortuosa' (corkscrew willow) were planted outdoors in 23 Apr. 1992. During the next year, forsythia, pussywillow, and corkscrew willow plants were either unpruned or pruned to 30–45 cm above the ground: 1) during dormancy or immediately after harvest (winter); 2) 3 to 4 weeks after start of shoot growth (spring); or 3) in early June (summer), and number and length of stems harvested was recorded for three years. Butterfly bush was either unpruned or pruned to 8 cm above the ground during: 1) winter or 2) spring, and number and length of stems recorded for 2 years. Stem length and number increased each year for all four species, and all species produced harvestable stems within 1 year after planting. For forsythia, no differences due to treatment were found, although year by treatment interactions were noted. The unpruned control produced the longest and greatest number of stems for pussy willow. Winter or spring pruning produced the longest and greatest number of stems for corkscrew willow. For butterfly bush, spring or no pruning produced the greatest number of stems, and year by treatment interactions were noted.
Euphorbia pulcherrima `Gutbier V-14 Glory' were grown with 220 mg·liter–1 N (20N–4.4P–16.6K) using ebb-and-flow (EF), capillary mat (CAP), microtube (MIC), and hand-watering (HAN) and were irrigated either daily (pulse - P) or as needed (regular - R). For all irrigation systems, pulse irrigation produced the greatest total dry weight. HAN-R produced lower total dry weight than all other irrigation systems and frequencies. Root dry weight was highest with pulse subirrigation (EF and CAP). MIC-P, EF-P, and EF-R were the most water-efficient treatments. The experiment was repeated twice with similar results. In a second experiment, Pelargonium ×hortorum `Pinto Red' root balls were sliced into three equal segments; top, middle, and bottom. For all irrigation systems, root counts were lowest in the top region. EF root counts were greatest in the middle region, while MIC root counts were greatest in the bottom region. The two subirrigation systems had higher average root counts than the two top-irrigated systems (HAN and MIC). In general, there was less difference in EC between regions for top-irrigated than for subirrigated root balls. The EC was lowest in the bottom and middle regions of EF and the bottom region of MIC and CAP. For subirrigation, the highest EC was in the top region. For all systems, pH was lowest in the bottom region.
Rock garden plants, typically alpine in nature, are indigenous to higher elevations and thus perform poorly in the South. Consequently, they are not adapted to environments with tight clay soils, extreme heat, high humidity, and periodic drought. A video and extension circular were produced to demonstrate the construction, planting and maintenance of an appealing yet durable rock garden for Oklahoma. Modifications in soil type, plant materials, and arrangement of rock, wherein small micro-habitats are created, comprise the core of the project. The aforementioned educational materials benefit the gardening public with previously unavailable information for Oklahoma. The video is included in the Oklahoma State Univ. Cooperative Extension Service video library, where it is available via rental or purchase. It provides informative visual instruction, complementing the written publication that outlines stepwise construction techniques coupled with a list of adaptable plants. Both the publication and video may have applications for gardeners in peripheral states.