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  • Author or Editor: C. R. Johnson x
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Abstract

α-Cyclopropyl-α-(4-methoxyphe-nyl)-5-pyrimidinemethanol (ancymidol) applied at 2 drench rates (0.25 mg and 0.50 mg/15 cm pot) controlled height and increased stem diameter of Chrysanthemum morifolium Ramat cv. Neptune grown in clay and plastic pots. Flower diameter was decreased by ancymidol treatments and anthesis was progressively delayed with increased rates. Watering frequency was reduced by use of plastic pots and growth regulator.

Open Access

Abstract

Roots of Carrizo citrange seedlings were inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus intraradices or provided an inoculum filtrate (non-VAM plants). Plants were exposed to drought stress after transplanting into large containers filled with a phosphorus amended medium (30 mg g-1). Drought stress caused reduction of phosphorus in leaf tissues and dry matter accumulation in VAM plants. However, phosphorus levels, dry weights, and transpiration of VAM seedlings were greater than non-VAM plants. Mychorrhizal infection appears to improve establishment of citrus into transplant situations by improving phosphorus uptake and reducing plant stress.

Open Access

Abstract

Freezing tolerances of 31 evergreen and semi-evergreen Ficus species growing out-doors at Fairchild Tropical Garden, Miami, Fla., were determined in late Dec. 1982. Five species, Ficus hookeriana Corner, F. montana Burm.f., F. rubiginosa Desf. ex Venten., F. tinctoria Forst.f., and F. trigonata L. survived freezing at −2°C whereas the hardiest species, Ficus pumila L., survived −4°. The other 25 species failed to survive freezing at −2°. A tender species, Ficus benjamina L., grown under natural environmental conditions in Gainesville, Fla., failed to survive a Jan. 1983 freeze of −4°. Freezing avoidance via supercooling appeared to be an effective means of survival for F. benjamina, as evidenced by 80% rooting in samples that supercooled to −2° and −4°.

Open Access

Nitrogen (N) and potassium (K) nutrition of Jalapeno peppers was determined on plants grown in sand culture. Varying rates of N (1 to 30 mM) and K (1 to 12 mM) in Hoagland's solution were evaluated to determine optimum nutrient concentration for plant growth and fruit production. Application of nutrient treatments were initiated at transplanting and flowering. A quadratic response to N rate was determined for biomass and fruit production per plant, regardless of when the N treatments were initiated. Plants that had N treatments initiated at transplanting were smaller and had less fruit. Optimum N rate for fruit yield was 15 mM. A linear response to K rate was determined for biomass, fruit number, and fruit weight per plant when nutrient treatments began at transplanting. A quadratic response to K rate was determined when K treatments began at flowering. Pepper plants that had K rates initiated at transplanting were smaller and had less fruit. The optimum K rates for fruit yield was 3 to 12 mM. Pungency of fruit was only affected by N rate treatments initiated at transplanting. 1 mM N reduced capsaicin levels in fruit as compared to other rates. Jalapeno peppers grown in sand culture required 15 mM N and at least 3 mM K for optimum fruit production.

Free access
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Abstract

Carnations (Dianthus caryophyllus cv. White Sim) planted August, 1970 were grown under long (LD) or normal (ND) daylengths and 4 continuous soil heating treatments, (none, 18°, 21°, 32°C). The rate of leaf unfolding and flower development was nearly equal for all treatments, although flowers appeared to initiate 3 weeks earlier under LD. Peaks of cut flower production were 1 month earlier and of greater magnitude under LD than ND. High soil temp (21°, 32°) under ND (winter daylengths) delayed peak flower production by another month. Total flower production was significantly greater with the plants grown under LD. Flowers from plants with high soil temp (21°, 32°), particularly those under LD, were of significantly better quality than those at 18° or without supplemental soil heat.

Open Access

Abstract

After 48 days rooting percentages and quality were highest for cuttings from Hibiscus rosa-sinensis plants grown under a reduced light intensity (65% natural light) regardless of (2-chloroethyl)phosphonic acid (ethephon) sprays at 100-5,000 ppm or indolebutyric acid (IBA) treatment to cuttings (0.8%). Ethephon and IBA treatments only affected cuttings from plants grown in 100% natural light, but rooting was not superior to that of cuttings from plants grown under reduced light. After 62 days, there were no treatment differences.

Open Access

Abstract

Partial shading, as a means of preventing or decreasing flower development, was used to study the influence of flowering on leaf rootability. Reduced light intensity decreased the size of flowers and sugar levels in leaves. The rooting-potential of leaves from plants grown under 25 percent shade was reduced compared to full sunlight controls; but was increased in the ones from under 95 percent shade. Exogenous hormone application improved rooting of leaves from full sunlight and 25 percent shade treatments, but reduced rooting in those from 95 percent shade. It was suggested that the reduction or prevention of flowering improves rooting-potential because of less active competition for materials necessary in rooting.

Open Access

Studies were conducted on the host plants of four billbug species (Coleoptera:Curculionidae: Sphenophorus parvulus Gyllenhal, S. venatus Chitt., S. inaequalis Say, and S. minimus Hart) found on New Jersey turfgrasses. A collection of 4803 adults from pure stands of various turfgrasses revealed all four billbugs on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb.), and perennial ryegrass (Lolium perenne L.), and S. parvulus, S. venatus, and S. minimus on Chewings fescue (F. rubra L. ssp. commutata Gaud.). Since the presence of larvae, pupae, or teneral adults more accurately indicates the host status of a grass species, immature billbugs were collected from plugs of the various grass species and reared to adults for identification. All four species were reared from immature billbugs found in Kentucky bluegrass turf; immatures of S. venatus, S. inaequalis, and S. minimus were found in tall fescue; S. venatus and S. minimus in perennial ryegrass; and S. inaequalis in strong creeping red fescue (F. rubra L. ssp. rubra). A laboratory experiment was also conducted in which billbug adults were confined in petri dishes with either Kentucky bluegrass, perennial ryegrass, tall fescue, or bermudagrass (Cynodon dactylon Pers.). Only minor differences were found between the four grasses in billbug survival, number of eggs laid, and amount of feeding. In general, bermudagrass was the least favored host and the other grasses were equally adequate hosts. The results of this study indicate a need for updating host-plant lists of these four billbug species.

Free access

Abstract

Three container-grown woody ornamentals (Viburnum suspension Lindl., Podocarpus macrophylla Thunb., Pittosporum tobira Thunb.) showed increased height, stem caliper, shoot and root fresh weight when inoculated with either Glomus fasiculatus (Thaxter) Gerd. & Trappe or G. mosseae (Nich. and Gerd.) Gerd. & Trappe endomycorrhizae.

Open Access

Abstract

High N fertilization reduced percent infection by Glomus spp. (Glomus fasciculatus (Thaxter Gerd. & Trappe and G. mossae (Nich. and Gerd.) & Trappe) endomycorrhizae on inoculated Podocarpus macrophyllus Thunb., Pittosporum tobira Thunb., and Rhododendron simsii Planch. plants. Inoculation with Glomus spp. benefited growth of the 3 woody plant species even at high levels of fertilization (1250 N, 1250 K and 230 Mg kg/ha·yr−1) although leaf nutrients levels showed little difference from noninoculated plants.

Open Access