Search Results

You are looking at 1 - 10 of 106 items for :

  • "Dendranthema ×grandiflorum" x
  • Refine by Access: All x
Clear All
Free access

Joseph J. King, Lloyd A. Peterson, and Dennis P. Stimart

Ammonium and NO3 uptake from hydroponic solutions containing 1 mm each of (NH4)2SO4 and Ca(NO3)2 were measured during development of Dendranthema ×grandiflorum (Ramat.) Kitamura `Iridon', `Sequoia', and `Sequest'. Nitrogen depletion from solutions approximated a 1 NH4: 1 NO3 ratio throughout a 90-day growth cycle (r = 0.96). Although harvest date cultivar interactions were significant for both forms of N, overall patterns of N uptake were similar among cultivars. Nitrogen removal from hydroponic solutions (milligrams per plant) was greatest from days 40 to 60; however, N removal (milligrams per gram of tissue dry weight) was greatest in the first month of development and decreased steadily until day 90. From day 40 to 60, new leaf development ceased while inflorescence buds developed to ≈1.0 cm in diameter. After this time, N uptake decreased rapidly as inflorescences expanded. Correlations between morphological changes and N demand could maximize the efficiency of applied N by matching form and application timing with plant needs.

Free access

Richard K. Schoellhorn, James E. Barrett, Carolyn A. Bartuska, and Terril Nell

Effects of heat stress on viable and nonviable axillary meristem development and subsequent lateral branching in 'Improved Mefo' chrysanthemum [Dendranthema ×grandiflorum Ramat. (Kitamura)] were studied. Plants grown at 33 °C day/27 °C night produced more nonviable buds than did plants grown at 23 °C day/18 °C night. A negative linear relationship {y = 28.7 + [-0.66 (x days)], r 2 = 0.70} between timing of exposure to high temperatures and the number of nonviable buds was observed. Histological examination 28 days after exposure to 33 °C/27 °C revealed that plants showed both normal and abnormal bud development. Abnormal bud development occurred as a consequence of premature differentiation of axillary meristematic tissue into nonmeristematic parenchyma tissue immediately after separation of axillary from apical meristems.

Free access

Nihal C. Rajapakse, David Wm. Reed, and John W. Kelly

Experiments were conducted to evaluate Dendranthema × grandiflorum (Ramat.) Kitamura cv. Bright Golden Anne quality and post-storage growth following storage in the range of 5 to 35C, initial soil water levels (60%, 80%, 100%), and durations (0 to 8 days). Transpiration rate showed a quadratic relationship with storage temperature. Initial soil water content had little effect on transpiration rate in dark storage environments. The lowest transpiration rate was observed in plants stored at 15 or 20C. Amino acid (AA) leakage and post-storage growth were well-correlated. Plants stored at or above 25C became etiolated during storage, while storage at 15C or below did not cause etiolation. Temperatures at or below 15C did not affect subsequent growth rate of chrysanthemum plants. Storage at 20C and above caused a reduction in post-storage growth rate following 2 days of storage.

Free access

H.F. Wilkins, W.E. Healy, and K.L. Grueber

For chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura], the hypothesis that a 12-hr 5C or 13C dark treatment could be used in conjunction with a 12-hr 27, 21, 17, or 13C light treatment for rapid flowering when applied during certain developmental stages was valid. Flowering of `Bright Golden Anne', planted on 23 Sept., was not delayed by 12-hr light/12-hr dark growth chamber treatments of 21/5C or 27/13C (day/night) if treated from planting (P) of the rooted cutting to the start of short days (SD), 3 weeks after start of SD to visible bud (VB) (SD + 3 to VB), or from VB to flower (F) when compared to the glasshouse control plants grown at 21/18C. Plants responded similarly if grown at 13/13C or 21/21C, but flowering was delayed compared to the 17/17C glass house control. Delays were absent, however, when 13/13C was used from P to SD, SD + 3 to VB, or when 17/13 or 21/13C was used from VB to F.

Free access

Jason R. Tutty, Peter R. Hicklenton, David N. Kristie, and Kenneth B. McRae

Stem elongation rate (SER) in Dendranthema grandiflorum (Ramat.) Kitamura was determined in light and in darkness under various temperature regimes. Stem growth as measured with linear voltage displacement transducers on plants in growth chambers. Under alternating 11-hour days and 13-hour nights, SER was strongly temperature dependent and showed patterns that were characteristic of the particular photoperiod-temperature regime under which the plants were grown. Total daily elongation was similar at constant 18.3C and at 11.5C days and 24C nights, but was much greater at 25.7C days and 12C nights. SER was rhythmic in continuous light with a period of slightly less than 24 hours. In continuous darkness, however, SER declined rapidly and the rhythm disappeared within 11 hours. Low-temperature pulses (a rapid decline from 18.3C to 8.3C) applied for 2, 4, 6, 8, or 11 hours during the day induced an immediate decline in SER followed by a slow recovery and peak shortly after the end of the pulse. Total diurnal stem growth declined with increasing pulse length, although short (2-hour) duration pulses apparently had little effect on growth. The results are discussed in relation to the influence of day and night temperature differentials (DIF) on stem growth in Dendranthema.

Free access

M.J. McMahon, J.W. Kelly, D.R. Decoteau, R.E. Young, and R.K. Pollock

`Spears' (nonpinched and pinched) and `Yellow Mandalay' (pinched) chrysanthemums were grown in growth chambers equipped with panels filled with liquids that served as spectral filters. Light quality was altered by reducing blue light, increasing red: far-red (R: FR) light, or reducing R: FR. Control panels did not selectively alter light transmission. Photosynthetic photon flux was the same in all chambers. All plants grown under increased R: FR filters had reduced height, reduced internode length, and increased chlorophyll content compared to controls. Reduction in blue light decreased chlorophyll content of pinched plants compared to controls. Pinched plants grown under increased R: FR light and !ong days developed fewer nodes than controls due to the formation of abnormal capitula; the controls and plants from the other treatments developed more nodes before producing similarly abnormal capitula. Stem diameter and leaf area did not differ due to treatments.

Free access

Kiffnie M. Holt and Paul H. Jennings

Rooted chrysanthemum cuttings of five cultivars were transplanted into 6 1/2″ pots and greenhouse-grown for 7 weeks under natural daylength conditions. Plants were pinched back twice, on the 3rd week and the 5th week following transplanting. At 7 weeks, plants were arranged in a complete randomized-block design with four plants per cultivar per treatment and three replications. Spacing of the pots was kept constant through the duration of the experiment. The chemical group was sprayed with 2500 ppm B-Nine until run-off on the first day of treatment. The mechanical group was brushed 40 times, twice a day, for 5 weeks. The brushing mechanism was adjusted daily to account for growth so as to stimulate only the top 2 to 3 inches of the plant. Measurements of all plants were taken on the first and last day of the mechanical treatment. Data collected included height, internode length, and leaf area. Plants were then allowed to flower under the naturally shortening daylength, and the flowering date was recorded. The chemical and mechanically treated plants were shorter than the controls with a greater response occurring with the cultivars `Emily' and `Cheery Emily', which had a more open and upright growth habit. Cultivar response differences and effects on internode length, leaf area, and flowering date were noted and will be discussed.

Free access

Amy J. MacKenzie, Terri Woods Starman, and Mark T. Windham

Trichoderma harzianum Rifai, a fungus that controls soilborne pathogens, can enhance growth of several vegetable and floriculture crops. Zero, 5, or 25 g of T. harzianum (isolate T-12) peat–bran amendment was added per kilogram medium in an effort to enhance the rooting of four chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitamura] cultivars, two considered easy to root (`Davis' and `White Marble') and two considered hard to root (`Dark Bronze Charm' and `Golden Bounty'). Adding the T. harzianum amendment at both rates tested increased root and shoot fresh weights during 21 days of rooting, relative to the control. Supplementary treated cuttings were transplanted into nontreated growing medium after 21 days. Midway between transplant to flowering, increases in height, shoot dry weight, and root fresh and dry weight were detected in `Dark Bronze Charm' with T-12, relative to the control; increases in height, shoot fresh and dry weight, and number of nodes were detected in `Golden Bounty' with T-12. By this time, there were no detectable differences in `Davis' or `White Marble'.

Free access

Toru Hayashi and Setsuko Todoriki

Aqueous solution (2%) of sucrose, glucose, fructose, or maltose delayed bloom wilting and foliage yellowing of cut chrysanthemums [Dendranthema ×grandiflorum (Ramat.) Kitamura] caused by gamma irradiation at 750 Gy. Solutions of silver thiosulfate, sodium dodecylbenzenesulfonate, polyoxyethylene lauryl ether, potassium sorbate, mannitol, sorbitol, glycerol, 6-benzylamino purine, and gibberellin did not reduce irradiation damage. Holding chrysanthemum cut flowers in a sucrose solution before and during irradiation did not influence the vase life, but holding the cut flowers in a sucrose solution following irradiation prolonged the vase life. The results suggest that sugars reduce radiation-induced physiological deterioration of chrysanthemums.

Free access

James E. Barrett, Carolyn A. Bartuska, and Terril A. Nell

Four experiments using container-grown Dendranthema ×grandiflorum (Ramat.) Kitamura `Nob Hill' or `Tara' were conducted to determine effects of application site and spray volume on uniconazole efficacy. Uniconazole applied only to mature leaves was less effective in controlling stem elongation than were stem applications, whole-plant sprays, or medium drenches. Spray volume altered efficacy more for uniconazole than for daminozide. Also, the effect of uniconazole spray volume was greater when the medium was not covered than when covered to prevent spray solution entering medium. Results from these studies showed the efficacy of uniconazole increased with increased stem coverage and with amount of chemical reaching the medium, which was achieved with high spray volumes. Chemical names used: (E)-1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-1-penten-3-ol) (uniconazole); butanedioic acid mono (2,2-dimethylhydrazide) (daminozide).