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- Author or Editor: H. B. Pemberton x
Abstract
Individual flowers from Rhododendron L. ‘Prize’ inflorescences were used at various stages of development for quantitative analysis of endogenous free abscisic acid (ABA) content by gas-liquid chromatography with electron capture detection. A decrease of endogenous ABA levels was observed in bud scale, petal, and gynoecium tissue during 6 weeks of cold treatment (9°C) given for release of floral bud dormancy. However, plants which received no cold treatment flowered as rapidly as plants exposed to 6 weeks of 9°. Therefore, a relationship between endogenous ABA levels and the capacity of azalea floral buds for continued development after a cold treatment could not be shown. Regression models of endogenous ABA content on respective morphological measurements of flower bud parts were computed to illustrate the relationship between destructive hormonal determinations and defined morphological changes over time.
Extensive field screening of rose (Rosa spp.) germplasm at two sites in Texas has determined that most modern roses are susceptible to blackspot [Diplocarpon rosae (Lib.) Wolf]. Fortunately, there is a high level of resistance in a number of diploid rose species, such as Rosa laevigata, R. ganksiae, R. rugosa, R. wichuraiana, and R. roxburghii. These species were used to create three amphidiploids: 84-1000 (R. roxburghii x R. laevigata), 86-3 (R. banksiae x R. laevigata), and 86-7 (R. wichuraiana x R. rugosa rubra). These were examined for fertility to determine their usefulness in a breeding program. 86-7 had the most abundant pollen production and the greatest pollen fertility, as measured by hip set (38%), followed by 86-3 (19%), and 84-1000 (13%). The female fertility of 86-3 and 84-1000 is low, and 86-7 is female-sterile. Although 86-7 showed poor female fertility, F1 hybrids exhibited a wide range of fertility, indicating that the fertility of this germplasm can be quickly increased in subsequent generations.
Plants of Rosa L. `RUIjef', `RUIdodo', and RUIrosora' were grown using a short-cycle production schedule. Rooted cuttings were established in 11.4-cm pots followed by pinching to start a final forcing period. Paclobutrazol was sprayed at 0, 25, 50, 100, or 200 mg·L-1 when shoots growing after the pinch were 2 to 3 cm long. Plants were harvested when at least two flowers were at stage 2 (showing color, calyx reflexing, no petals reflexed). At harvest, plants were moved to a simulated interior environment at 21 °C with 30 lower case μmol·m-2·s-1 fluorescent light. Plants of `RUIjef' had the most flowers per pot, whereas plants of `RUIdodo' were the shortest and the latest to flower. Plants of `RUIrosora' exhibited the longest shelf-life, but cultivars responded similarly to paclobutrazol treatments. Paclobutrazol treatment at 50 mg·L-1 and above resulted in shorter plants than the control while 25 mg·L-1 and above reduced peduncle length. Days to harvest was unaffected. Plant shelf-life was reduced 2.1 d by 100 or 200 mg·L-1 paclobutrazol treatment in comparison to the control. Longevity of selected individual flowers was reduced 1.4 d after 50 mg·L-1 treatment and by 2.2 d after 100 mg·L-1 treatment. Leaf abscission during the interior evaluation period was significantly reduced by paclobutrazol treatment of 50 mg·L-1 or higher, but leaf abscission overall was less than 10%. Considerations of height control, plant shelf-life and floral longevity should be balanced when using paclobutrazol in miniature pot rose production.
Orange end Red Sunblaze miniature rose plants were forced. to flower in a glasshouse in 10 cm pots. At harvest, flower stage (FST) 1 (tight bud), 2 (reflexed calyx), and 3 (petals starting to reflex) flowers were designated and tagged. The plants were then stored at 4, 16 or 28°C for 2, 4, or 6 days. Subsequent to the simulated shipping treatments, plants were evaluated in a simulated home interior environment (21° with 30 μmoles M-2 sec-1 cool-white fluorescent light). After summer forcing, flowers of both cultivars developed at least 1 FST during simulated shipping. Flower development increased as storage duration increased for FST 1 and 2, but storage duration did not affect development of FST 3 flowers. The higher the temperature the faster flowers developed, but development was less than 1 FST at 4°. After winter forcing, flowers developed less than 1 FST during simulated shipping. Flower development increased with increasing temperature. In summer, plants with FST 2 flowers could be shipped at up to 16°, but plants with FST 3 flowers should be shipped at 4°. In winter, plants can be shipped at up to 16° with FST 3 flowers.
Plants of Rosa `Mr. Lincoln' and `Peace' were established in March 1992. Using a RCB design, fungicide treatments were initiated on 15 May and terminated on 22 Oct. 1992. Foliar applications were made with a Birchmeier® Closed System Unit equipped with a ConeJet® #5500 adjustable spray tip at 50-65 psi. Treatments were cyproconazole at 0.1, 0.2, and 0.4 kg·ha-1 applied at either 14 or 28 day intervals, mancozeb at 2.250 g·1-1 applied every 7 days, and an untreated control. Cyproconazole treatments were applied in 946 1·ha-1 water and mancozeb was sprayed to runoff. Disease pressure and plant defoliation ratings were taken on 29 June and 26 August. The disease rating was based on a scale of 1-10, where 1 = no infection and 10 = severe infection and defoliation. The defoliation rating was based on a scale of 1=10, where 1=0-10% and 10=91-100% defoliation of canopy. A full season control rating was determined on 17 Nov. 1992, based on a scale of 1-3, where 1=excellent, 2=acceptable, and 3=unacceptable control of blackspot. Blackspot control with mancozeb was unacceptable on either cultivar. Cyproconazole at 0.1 kg·ha-1 every 28 days did not control blackspot by mid-November with `Peace' and was marginally acceptable on `Mr. Lincoln'. Season long disease control was near excellent for both cultivars with 0.2 kg·ha-1 cyproconazole every 28 days. All other cyproconazole treatments proved to be excellent.
Abstract
Ancymidol foliar spray at 66 and 132 mg·liter−1 a.i. significantly decreased height, node number, leaf area, fresh weight, and dry weight of four sunflower cultivars. Ancymidol resulted in darker green leaves and increased chlorophyll content per unit area, as measured spectrophotometrically, when compared with controls. However, chlorophyll a, b, and total chlorophyll were increased in only two cultivars when measured on a weight basis using high-performance liquid chromatography (HPLC). Ancymidol increased three xanthophyll levels (neoxanthin, vio-laxanthin, and lutein) in the four cultivars, but had no effect on β-carotene when measured on a weight basis by HPLC. Chemical name used: a-cyclopropyl-a-(4-methoxyphenyl)-5-pyrimidine methanol (ancymidol).
Perennial ryegrass (Lolium perenne) has traditionally been used to overseed warm-season grasses in the southern U.S. when warm-season sods are dormant due to chilling temperatures. In this study we investigated overseeding turf-type annual ryegrass (two cultivars of L. multiflorum and one cultivar of L. rigidum) and chewing fescue (Festuca rubra var. commutata) as well as perennial ryegrass onto a warm-season common bermudagrass (Cynodon dactylon) sod. The objective was to compare turf quality, turf color, and transition date of turf-type annuals with perennials and other cool-season grasses. Results for turf quality indicated that the annual ryegrass cultivars `Axcella' and `Panterra' (L. multiflorum) compared very well with perennials through March; however, in April and May, perennials were superior for quality. `Hardtop' fine fescue is a hard fescue (F. ovina var. duriuscula). It was inferior to the annuals for turf quality from December to April when the annuals began to die. For turf color, annuals had a lower rating compared to dark green perennials such as `Premier II', `Derby Supreme', or `Allstar'. `Panterra' was darker compared to `Axcella' in March and April. Chewing fescue was intermediate in color compared to annuals and perennials. For turf height, `Axcella' was taller than `Panterra', which were both taller than the perennials, and the fine fescues were shorter than the perennials. For transition in the spring, the annuals had a shorter transition and died about 1 month earlier than the perennials. `Transtar' (L. rigidum) had an earlier transition than the other annuals. The perennials tended to have a longer transition period. The fescues had a very long transition period and were similar to the perennials.
Plants of Rosa L. `Peace' were field planted in Feb. 1995 in order to test black spot (Diplocarpon rosae Wolf) control efficacy of several compounds. Plants were protected from fungal infection by black spot with weekly sprays of chlorothalonil (Daconil) from 5 Apr. to 8 June 1995 to allow plant establishment. Spray treatments for efficacy testing were started on 23 June and ended on 1 Nov. 1995. All plants were uniformly weeded, fertilized, and irrigated as needed for the duration of the experiment. Plants were rated for defoliation and disease development on 18 July, 1 Sept., and 10 Nov. 1995. A wettable granular formulation of cyproconazole (Sentinel) controlled black spot significantly better when a surfactant, Latron B-1956, was added to the spray solution at 0.5 mL·L–1. Differences between treatments with and without surfactant were greater at lower rates vs. higher rates of cyproconazole. The most effective Sentinel rates with the surfactant were 0.13 g·L–1 applied every 14 days or 0.26 g·L–1 every 21 days. A formulated combination of chlorothalonil and thiophanate methyl (ConSyst) controlled black spot on a 7-day interval at 1.2 g·L–1, but not when applied at 1.8 g·L–1 every 14 days. Control was no better than the standard mancozeb (Dithane) treatment. Neem oil (NeemGard) was not effective on the 14-day schedule tested. Tank mixing neem oil with chlorothalonil or thiophanate methyl (Domain) did not significantly improve control. Neither myclobutanil (Systane) or a formulated combination of mancozeb and myclobutanil (RH 0611) was effective in controlling black spot.
Viola tricolor seed were exposed to aerated solutions of water or 300 or 400 mM NaCl for 0, 2, 4, 6, or 8 days. After priming treatments, seed were air dried, placed on moist filter paper in petri dishes, and set in dark growth chambers at 18 or 30°C for germination. priming for 6 days in water increased germination of `Crystal Bowl Yellow' seed from 80 to 88% when germinated at 30 °. Untreated seed germination was 92% at 18°. Priming for 6 days in 300 mM NaCl improved germination of `Majestic Giant Blue' seed from 57 to 76% when germinated at 30°. Untreated seed germination was 80% at 18°. These data indicate that seed priming could be used to improve summer germination of a cool season annual. Priming increased germination at the higher than optimum temperature (30°) to levels similar to that for the optimum temperature (18°). However, the best priming solution depended on the cultivar.
Abstract
Easter lily (Lilium longiflorum Thumb. ‘Nellie White’) bulbs forced under an 8-hr duration of fluorescent light at 400 μmol·s−1·m−2 were acceptable for commercial sales. The total number of flowers initiated were not influenced by light intensity or duration during forcing. The number of flowers reaching anthesis was influenced by light duration. Ancymidol was effective in reducing internode elongation.