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- Author or Editor: Douglas A. Bailey x
Abstract
All growth retardant treatments (ancymidol, 50 mg·liter−1, one or two sprays; uniconazole, 5, 10, or 15 mg·liter−1, one or two sprays; 20 mg·liter−1, one spray) reduced Easter lily (Lilium longiflorum Thunb.) plant heights when compared to controls. Plant heights decreased linearly with increasing concentration of uniconazole for both one- and two-spray treatments. High concentrations of uniconazole delayed anthesis; ancymidol treatments did not. Individual corolla length was not affected by treatments. Treatments did not affect daughter bulb depletion or new daughter bulb growth. Total leaf area and leaf dry weight decreased as uniconazole concentration increased; ancymidol treatments did not affect leaf area, but did reduce leaf dry weight. Leaf total soluble carbohydrate decreased with increasing concentration of uniconazole. Chemical names used: α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidine-methanol (ancymidol); (E)-1-(p-chlorophenyI)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (uniconazole).
Plants of Euphorbia pulcherrima Wind. `Glory' were grown under 13.4, 8.5, or 4.0 mol·m-2·day-1 and sprayed with water (control); 2500 mg·liter-1 daminozide + 1500 mg·liter-1 chlormequat chloride (D+C); 62.5 mg·liter-1 paclobutrazol; or 4, 8, 12 or 16 mg·liter-1 uniconazole to ascertain plant developmental and pest-production responses to the treatment combinations. Days to anthesis increased as irradiance was decreased. Anthesis was delayed by the D+C treatment, while other growth retardant (GR) treatments had no effect on anthesis. Irradiance did not affect plant height at anthesis, but all GR treatments decreased height over control plants. Bract display and bract canopy display diameters declined as irradiance was decreased. Growth retardants did not affect individual bract display diameters, but all GR treatments except paclobutrazol reduced bract canopy display diameter. Plants grown under lower irradiance had fewer axillary buds develop, fewer bract displays per plant, and fewer cyathia per bract display. Cyathia abscission during a 30 day post-anthesis evaluation was not affected by treatment; however, plant leaf drop was linearly proportional to irradiance. All GR treatments increased leaf drop over controls, and the D+C treated plants had the highest leaf loss. Results indicate the irradiance and GR treatments during production can affect poinsettia crop timing, plant quality at maturity, and subsequent post-production performance.
Plants of Euphorbia pulcherrima Wind. `Glory' were grown under 13.4, 8.5, or 4.0 mol·m-2·day-1 and sprayed with water (control); 2500 mg·liter-1 daminozide + 1500 mg·liter-1 chlormequat chloride (D+C); 62.5 mg·liter-1 paclobutrazol; or 4, 8, 12 or 16 mg·liter-1 uniconazole to ascertain plant developmental and pest-production responses to the treatment combinations. Days to anthesis increased as irradiance was decreased. Anthesis was delayed by the D+C treatment, while other growth retardant (GR) treatments had no effect on anthesis. Irradiance did not affect plant height at anthesis, but all GR treatments decreased height over control plants. Bract display and bract canopy display diameters declined as irradiance was decreased. Growth retardants did not affect individual bract display diameters, but all GR treatments except paclobutrazol reduced bract canopy display diameter. Plants grown under lower irradiance had fewer axillary buds develop, fewer bract displays per plant, and fewer cyathia per bract display. Cyathia abscission during a 30 day post-anthesis evaluation was not affected by treatment; however, plant leaf drop was linearly proportional to irradiance. All GR treatments increased leaf drop over controls, and the D+C treated plants had the highest leaf loss. Results indicate the irradiance and GR treatments during production can affect poinsettia crop timing, plant quality at maturity, and subsequent post-production performance.
Summer spray applications of 5000 ppm daminozide (1× or 2×), 62 ppm paclobutrazol (1× or 2×), or 5 ppm uniconazole (1× or 2×) were applied to seven cultivars (Böttstein, Enziandom, Kasteln, Mathilde Gütges, Merritt's Supreme, Red Star, and Schenkenburg) of florists' hydrangea [Hydrangea macrophylla subsp. macrophylla var. macrophylla (Thunb.) Ser.] to evaluate cultivar response to plant growth retardants (PGRs). Both daminozide treatments and the 2× uniconazole treatment effectively reduced plant height for all cultivars during the summer growth period; cultivars varied in response to the paclobutrazol treatments and the 1× uniconazole treatment. Daminozide and uniconazole treatments resulted in less elongation than all other treatments during forcing for most cultivars tested. Paclobutrazol treatments had no residual effect on shoot elongation during forcing of the cultivars tested. The 2× treatments of all PGRs decreased inflorescence diameter of some of the cultivars tested compared with nonsprayed controls. Results from this study indicate that 1) summer application of PGRs can have a residual effect on plant height and inflorescence diameter of hydrangeas during the spring greenhouse forcing phase; and 2) hydrangea cultivars differ significantly in response to the PGRs tested. Therefore, the need for height control during the spring forcing period of hydrangeas will vary with cultivar, and it will depend on how plants were treated the previous summer growing season. We recommend that producers of dormant hydrangeas provide records of their summer height control program to forcers so that height control programs during spring forcing can be adjusted appropriately.
Abstract
Plants of Euphorbia pulcherrima Willd.‘Glory’ received seven biweekly 236.5-ml soil drenches, each containing either 0, 10, 40, 80,160, or 320 mg Mo/liter (0, 2.4, 9.5, 18.9, 37.8, and 75.7 mg/pot). No visible phytotoxic effects due to excess Mo were observed on any plants, and no treatment differences were evident for plant height at anthesis, days from start of short days to anthesis, or display bract diameter at anthesis. Foliar nutrient analyses indicated no effect on nutrient uptake due to treatment for any element except Mo. A level of 806 mg Mo/kg dry weight were recorded for poinsettia leaves without adverse effects on plant growth or appearance. Results suggest Mo toxicity is not a real threat in poinsettia production.
Abstract
Seed of Lycopersicon esculentum Mill. ‘Champion’ and Petunia hybrida Vilm. ‘Snow Cloud’ were irrigated with either nonacidified solution (0.15, 0.30, or 0.45 ml) of 75% H3PO4·liter−1; or 0.11, 0.20, or 0.26 ml of 46.5% H2SO4·liter−1. Germination was not affected by acidification, yet seedling growth was enhanced for both species. Growing medium and plant shoots were analyzed for N, P, K, Ca, and Mg content. Although nutrient levels were affected by acidification, no nutrient deficiency or phytotoxicity due to irrigation water acidification was evident.
Abstract
Terminal cuttings of Hydrangea macrophylla Ser. ‘Rose Supreme’, ‘Merritt’s Supreme’, and ‘Sister Therese’ were treated with basal dips of 0, 5000, 10,000, or 20,000 mg/kg IBA-talc and allowed to root in 22°C sand under mist for 0, 1, 2, 3, 4, or 5 weeks. Adequate root-system development required 4 weeks for ‘Sister Therese’ treated with 10,000 or 20,000 mg/kg IBA, and 5 weeks for ‘Merritt’s Supreme’ treated with 5000, 10,000, or 20,000 mg/kg IBA. After 5 weeks under mist, no cuttings of ‘Rose Supreme’ had developed an adequate root system. ‘Merritt’s Supreme’ hydrangeas were irradiated continuously with 0 or 84 ± 3 μmol -2s-1, supplemental photosynthetically-active radiation (PAR) supplied by high-pressure sodium vapor lamps, and were grown in an 18°-minimum-temperature greenhouse during the winter months. Plants receiving PAR concomitant with natural daylight developed 7 expanded leaf pairs after 9 weeks, whereas control plants required 12 weeks to reach the same stage. Plants receiving supplemental PAR were significantly taller, yet acquired less leaf and stem dry weight and less leaf area than did plants receiving natural daylight alone.
Abstract
Nutrient imbalances were investigated to a) document nutrient deficiency and micronutrient toxicity symptoms in florists’ hydrangea (Hydrangea macrophylla Thunb.) and b) examine the possible relationship of single-element deficiencies and toxicities with a foliar malformation prevelant on hydrangeas grown at >30°C. Plants subjected to N, P, K, Ca, Mg, S, B, Fe, and Zn deficiency and B and Mn toxicity treatments produced visual symptoms of the corresponding nutrient imbalance. Visual symptoms did not develop in +Fe, +Cu, +Zn, +Mo, −Mn, −Cu, and −Mo treatments. None of the symptoms induced were similar to the foliar malformations observed on hydrangeas grown at >30°. Hydrangea leaf malformation does not appear to be correlated with any single nutrient imbalance within hydrangea leaves. Results of the nutrient deficiency and toxicity experiments offer a diagnostic tool for interpretation of nutrient analysis of hydrangea.
Abstract
Plants of Hydrangea macrophylla Thunb. were grown in various environments to identify factors responsible for the appearance of malformed hydrangea leaves and to screen cultivars for tolerance to the foliar disorder. Ambient temperature, photosynthetic photon flux (PPF), and root system temperature were studied. Hydrangea leaf malformation is under thermal control and can be stimulated by ambient temperatures of 33/26C (light/dark), but these must be maintained to sustain the development of distorted foliage. Placement of plants with malformed leaves into a 26/22C (light/dark) environment resulted in subsequent development of typical leaves. A PPF of 506 μmol·s−1·m−2 resulted in a more rapid appearance of distorted leaves than a PPF of 224 μmol·s−1·m−2. Reducing the root system temperature below the ambient level of 32/28C to 20/18C (light/dark) reduced, but did not prevent, the development of malformed leaves. ‘Blau Donau’ and ‘Tricolor’ did not develop malformed foliage during 22 weeks of growth at 32/26C (light/dark). ‘Rose Supreme’, ‘Merritt's Supreme’, ‘Rosa Rita’, and ‘Dr. Bernard Steiniger’ had developed malformed leaves by week 8 of treatment. For ‘Rose Supreme’ and ‘Blau Donau’, leaves developing at the higher temperatures had shorter and narrower laminae, less fresh weight and surface area, and more dry weight per unit area than plants at the lower temperatures. Laminae developing at the higher temperatures were thicker due to an increase in adaxial palisade parenchyma tissue. Malformed ‘Rose Supreme’ leaves had fewer intercellular spaces than normal leaves and lacked an observable spongy parenchyma layer. However, laminae of ‘Blau Donau’ leaves developed a distinct, yet thinner, spongy parenchyma layer at the higher than at the lower temperatures; intercellular spaces were still prevalent in the spongy parenchyma layer at the higher temperatures.
Abstract
Plants of Hydrangea macrophylla ‘Rose Supreme’, ‘Merritt's Supreme’, and ‘Sister Therese’ produced inflorescence primordia more effectively under 8-hr photoperiods than under continuous photoperiod (CP) at 24°C. Inflorescence primordia were present on all plants under 8-hr photoperiods after 16 weeks, whereas plants under CP remained vegetative. Plants under CP sustained internode elongation throughout the experiment, whereas plants under 8-hr photoperiods remained short with little increase in number of expanded leaf pairs. Continuous photoperiod inhibited floral initiation of ‘Rose Supreme’ and ‘Merritt's Supreme’ plants at 24°C, yet had little effect at 18°C. ‘Sister Therese’ plants bloomed freely, regardless of photoperiod. Daminozide (3 biweekly foliar sprays of 5000 mg/liter) inhibited floral initiation of ‘Rose Supreme’ and ‘Sister Therese’ plants. Plants of all 3 cultivars flowered more rapidly at 24° than at 18°, whereas photoperiod had no effect on flowering date. Inflorescences were larger and plants were taller at 24°C than at 18°C. Continuous photoperiod increased inflorescence diameter and plant height at 24°C but had little effect at 18°C. Plants treated with daminozide were shorter than untreated plants, regardless of temperature or photoperiod.