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  • Author or Editor: C.N. Johnson x
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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

Abstract

‘Shasta’ chrysanthemum (Chrysanthemum morifolium Ramat) showed less SO2-induced leaf necrosis than ‘Hurricane’. The growth retardant a-cyclopropyl-a-(4-methoxy-phenyl)-5-pyrimidine methanol (ancymidol) at 0.16 and 0.48 mg ai/2.5 cm pot reduced SO2 damage on both cultivars. There was positive correlation between stomatal activity (water diffusion resistance) and degree of leaf necrosis from SO2.

Open 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

Abstract

Combination treatments containing an organic phosphate or carbamate nematicide, a herbicide, and a fungicide on a common granule controlled root-knot nematodes and weeds and increased tomato (Lycopersicon esculentum Mill.) plant growth. Bay 68138 + diphenamid, ethoprop + diphenamid, Bay 68138 + pebulate + Dexon, fensulfothion + isopropalin + Dexon, Bay 68138 + isopropalin + Dexon, and ethoprop + isopropalin + Dexon completely controlled root-knot nematodes. Isopropalin and pebulate controlled FL pusley and crabgrass as effectively as diphenamid, the standard herbicide. Ethoprop + pebulate, fensulfothion + pebulate + Terrazole, ethoprop + pebulate + Dexon, and Bay 68138 + pebulate + Dexon were phytotoxic to tomato seedlings early in the growing season. Formulations containing a nematicide + herbicide + fungicide can be spread on the soil surface just before planting and incorporated with a power-driven rototiller to reduce unit production costs of tomato transplants. Production of uniform transplants free of nematodes and relatively free of weeds can facilitate mechanical harvesting.

Open Access

Abstract

The effect of 0, 250, 1000, 3000, 5000, 7500, 10,000, and 15,000 ppm solution of NaCl:MgCl2 in a 10:1 ratio was determined on Chinese fan palms [Livistona chinensis (Jacq.) R Brown] grown in soil or nutrient solution. Plants grown in soil and drenched weekly with 10,000 ppm ceased growth within 2 months, while palms grown in nutrient solution exhibited a reduced growth rate with increasing salinity levels. Tissue analysis showed increased levels of Na and Mg in plant tissue with increased saline substrate levels, with highest Na and Mg tissue levels in fronds from container-grown palms.

Open Access

Abstract

Soil drench of (2-chloroethyl)phosphonic acid (ethephon) at 500 or 1000 mg (active ingredient)/25-cm pot, caused prostrate growth habit and fruit set on Ficus benjamina L. grown in full sun or 47% shade. Leaves of sun plants generally had a mesophyll with multiple palisade layers, while shade plants had only limited regions of multiple cells. Ethephon treatments reduced intercellular spaces in palisade and spongy mesophyll cells, particularly near leaf margins. High shoot/root ratios, reduced leaf area, and heavy leaf drop during an interior phase occurred with ethephon treatment, especially plants grown under full sun.

Open Access

Abstract

The effects of 2 light levels, (full sun and 47% shade) 3 nitrogen and 3 potassium levels (672, 2018, and 3362 kg/ha yr-1) on light compensation point, shoot and root growth, canopy distribution and leaf tissue nutrient content of Ficus benjamina were determined. The 47% shade treatment during 7 months of production significantly decreased light compensation point levels. N level slightly affected compensation point and K level had no effect. Higher N levels increased shoot growth, while K levels played a dominant role in root development. Light level interacted with both of these effects. N level was positively correlated to percent of the plant canopy contained in the upper half of the plant and this in turn closely was correlated with plant light compensation point.

Open Access

Clematis socialis Kral, commonly known as the Alabama Leatherflower, is an endangered species with only six known populations in northeast Alabama and northwest Georgia. Cutting propagation of the species will aid in establishing additional self-sustaining populations and provide genetic material for future hybridization and genetic preservation. Such research would also benefit growers, especially native nurseries, who wish to produce this species commercially for its ornamental value. Several experiments were performed to determine the effects of four non-amended substrates on root initiation, root growth, and survival of C. socialis stem cuttings. The four substrates tested included sand, perlite, vermiculite, and a 1 peat (P): 1 pine bark (PB): 1 sand (S) mix (by volume). Some of the best results in the preliminary experiments in 2000 were observed when 2 to 3 node cuttings kept under shade and treated with higher IBA/NAA concentrations were used. In 2004, there was a correlation between root growth and cutting survival and particle size of the substrates. Cuttings rooted in the finer-particle substrates sand and vermiculite had higher cutting survival, root growth, root number, and root quality than those rooted in perlite and the 1 P: 1 PB: 1 S mix. Sand, perlite and vermiculite consistently outperformed the 1 P: 1 PB: 1 S mix which had some of the lowest growth data means. Sand was among the highest performing substrates in all years and it is the most inexpensive and readily available making it the most logical substrate for rooting C. socialis stem cuttings.

Free access

Clematis socialis Kral, also known as the Alabama Leatherflower, is an endangered species with only six known populations in northeast Alabama and northwest Georgia. Cutting propagation of the species would be beneficial for establishing additional self-sustaining populations and providing genetic material for future hybridization. A study conducted in 2000 and 2004 determined the effects of four nonamended substrates on root initiation and growth, as well as survival of C. socialis stem cuttings. Of the four substrates tested, including sand, perlite, vermiculite, and 1:1:1 (by volume) peat (P): pine bark (PB): sand (S), cutting survival was highest in sand in both 2000 and 2004. In 2000, sand also produced the longest roots and highest root quality. Vermiculite produced the longest and most roots and highest root quality in the 2004 study. In 2004, cuttings rooted in fine-particled substrates, such as sand and vermiculite, had higher cutting survival, root growth, root number, and root quality than those rooted in perlite and 1:1:1 (by volume) P:PB:S. The 1:1:1 P:PB:S substrate produced the lowest averages for all data collected in both the 2000 and 2004 studies. Sand was among the two highest performing media in both years, regardless of differences in IBA concentration, misting times, and environmental conditions, making it the overall best substrate for rooting C. socialis stem cuttings. Increasing the concentration of IBA in the rooting solution, providing a cooler environment, and decreasing the number and duration of misting cycles the cuttings received increased cutting survival, root length, root number, and root quality for all four substrates from 2000 to 2004.

Free access