Search Results

You are looking at 91 - 100 of 791 items for :

  • bedding plant x
  • Refine by Access: All x
Clear All
Free access

Paul A. Thomas and Joyce G. Latimer

66 ORAL SESSION 15 (Abstr. 478–484) Plant Growth Regulators/Marketing–Floriculture/Foliage

Free access

Krishna S. Nemali and Marc W. van Iersel

Optimal substrate volumetric water content (θ) and drought tolerance of impatiens, petunia, salvia, and vinca were investigated by growing plants under four constant levels of θ (0.09, 0.15, 0.22, and 0.32 m3·m-3). Gas exchange, quantum efficiency (ΦPSII), electron transport rate (ETR), non-photochemical quenching (NPQ), and leaf water potential (ϒ) were measured for all species, and response of photosynthesis (Pn) to internal CO2 concentration (Ci) was studied in petunia and salvia. Leaf photosynthesis (Pmax) was highest at a θ of 0.22 m3·m-3 for all species and did not differ between a θ of 0.15 and 0.22 m3·m-3 for vinca and petunia. The Pn-Ci response curves for petunia were almost identical at a θ of 0.22 and 0.15 m3·m-3. Regardless of species, ETR and ΦPSII were highest and NPQ was lowest at a θ of 0.22 m3·m-3. Based on these results, a θ of 0.22 m3·m-3 for salvia and impatiens and a slightly lower θ of 0.15 m3·m-3 for vinca and petunia, is optimal. Mean osmotic potential in all treatments was lower in vinca and salvia and resulted in higher turgor potential in these species than other species. Analysis of Pn-Ci response curves indicated that Pn at a θ of 0.09 m3·m-3 was limited by both gas phase (stomatal and boundary layer) and non-gas phase (mesophyll) resistance to CO2 transfer in salvia. At the lowest θ level, Pn in petunia was only limited by gas phase resistance, indicating that absence of mesophyll resistance during drought may play a role in the drought tolerance of petunia.

Full access

Kimberly A. Klock-Moore

Horticultural Compost Technology class at the University of Florida for making the GHC compost, and Lovell Farms, Miami, for the plant material and the used greenhouse growing substrate. This work was supported in part by a grant from the Center for Biomass

Full access

Michael A. Schnelle, B. Dean McCraw, and Timothy J. Schmoll

Blakely, Creekside Plants, Oologah, Okla., for their ingenuity and contribution of time, labor, and greenhouse space.

Free access

Cynthia B. McKenney and Marihelen Kamp-Glass

The effectiveness of antitranspirant type and concentration on the leaf water relations of Saliva splendens F. `Firebird and Petunia × hybrida Juss. `Comanche'. Two film-forming antitranspirants, Cloud Cover and Folicote, were tested at three different concentrations in two different environments. The leaf water potential, stomatal conductance, and relative water content were evaluated. Transpiration per unit vapor pressure deficit and stomatal conductance for both crops decrease slightly but there was no trend with respect to the film type, environment or concentration rate. The leaf water potentials and relative water content did not show significant difference after antitranspirant application. In order for antitranspirant application to be of benefit to the growth of herbaceous plants, a more durable coating that remains semipermeable would have to be utilized.

Free access

Chi Won Lee, Gye-Soon Jeong, and Byoung-Ryong Jeong

Toxicity symptom of micronutrients copper, magnesium and zinc were investigated for geranium, marigold, vinca and zinnia. Plants were grown in peat-lite mix in 11 cm plastic pots and watered with nutrient solutions containing 0.05, 0.5, 1, 5, 10 mM concentrations of Cu2+, Mg2+ and Zn2+. In most species, the concentrations of these micronutrients higher than 5 mM greatly reduced plant growth and induced stem and foliar toxicity symptoms. Toxic levels of Cu2+ and Zn2+ reduced plant and leaf sizes without producing leaf spots in all species tested. Toxicity symptom of Mn2+ were characterized by numerous chlorotic or brown leaf spots. Visual leaf toxicity symptoms of these 3 micronutrients in each species are illustrated.

Free access

Joyce G. Latimer and Ronald D. Oetting

Two weeks after planting, plugs of New Guinea impatiens (Impatiens × hybrida), marigold (Tagetes erecta), or ageratum (Ageratum Houstonianum) were subjected to eight conditioning treatments: untreated, low N (50 ppm), high N (500 ppm), ebb/flow watering, drought, brushing (40 strokes twice daily), daminozide (5000 ppm), or paclobutrazol (45 ppm). Fertilizers were applied three times per week at 250 ppm N for all plants not treated with high or low N. Five adult twospotted spider mites were placed on each plant 1 week after treatment. New Guinea impatiens height was reduced by low N, brushing, or paclobutrazol at 4 weeks after treatment. Spider mite populations were reduced only by brushing. Marigold height was reduced by low N, drought, or brushing, but spider mite counts were reduced by brushing or paclobutrazol. Height of ageratum was reduced by low N, daminozide, or paclobutrazol, but spider mite counts were reduced by ebb/flow or brushing at 4 weeks after treatment.

Free access

Douglas A. Cox

`First Lady' marigold (Tagetes erecta L.) and `Selenia' New Guinea impatiens (NGI; Impatiens sp. hyb.) were grown in solution culture for 60 days. At 10-day intervals, plants received low N for 10 days (marigold) or 20 days (NGI). Low-N treatment was 5% and 10% of the control, respectively, for marigold and NGI. After each low-N period, FW of treated and control plants was measured and N uptake by the controls was determined by solution depletion. Nitrogen uptake by marigold reached a peak 40 days after planting, and then decreased somewhat during the final 20 days of the experiment. In contrast, N uptake by NGI increased gradually after planting, reaching its highest level at the end of the experiment (60 days). Low-N periods 10 to 20 and 20 to 30 days after planting reduced the FW of marigold about 35% vs. control. FW reductions resulting from earlier or later low-N periods were much smaller or did not occur. Reductions in NGI FW resulted from low-N periods 20 to 40, 30 to 50, and 50 to 60 days after planting. While short periods of low N reduced the growth of both species, these reductions were desirable and not excessive, and no foliar symptoms of N deficiency were apparent at any time. Results of these experiments have implications for efficient fertilizer use and growth suppression using short periods of low nutrition.

Free access

Dharmalingam S. Pitchay, James L. Gibson, C. Ray Campbell, Paul V. Nelson, and Brian E. Whipker

The margin of error in pinpointing the difference in deficiency symptoms between calcium and boron is high. Several experiments were conducted in the greenhouse to induce as well as to differentiate the exact foliar and root symptoms of Ca and B. The experiments were conducted with modified Hoagland nutrient solutions. The treatments were with or without Ca or B salts for inducing total deficiency symptoms. Symptoms were expressed on the upper part including the growing point of the plant. In absence of Ca, marigold and zinnia plant heights were reduced by 58% and 37%, respectively, from the control. However, the reduction in height was only in the 27% and 25% range for B deficiency. Ca deficiency was noted as a blackened region on the leaf blade (early stage symptoms) which progressed into necrotic spots on the newly formed leaves. Severe necrosis, was observed on the growing point with advanced Ca deficiency. B deficiency results in a leathery and gray color in zinnia, needle like and narrow leaflets in marigold. The leaf blades were brittle in all B deficient species. B deficient plants roots were stiff and leathery and lateral roots possessed black nodule like endings at the tips. The Ca deficient roots expressed less side branching and at the advanced stage the roots were shorter and fewer with severe necrotic symptoms. The above initial and advanced deficiency symptoms appeared earlier in treatments without Ca than B. Images of Ca and B deficiency symptoms, as well as tissue concentration values will be presented.

Free access

Holly L. Scoggins, Douglas A. Bailey, and Paul V. Nelson

1 Current address: Dept. of Horticulture, Virginia Tech, 301C Saunders, Blacksburg, VA 24061 2 Current address: Dept. of Horticulture, Univ. of Georgia, 1111 Plant Science Bldg., Athens, GA 30601. The research reported herein was funded in