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  • Author or Editor: G. E. Beck x
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Abstract

Five selections of cape primroses (Streptocarpus Xhybridus Voss.) were developed for the commercial greenhouse industry as flowering potted plants and approved for release in April 1983. The new cultivars exhibit compact, vigorous growth, improved heat tolerance, and abundant flower production. The flower colors, shapes, and patterns offer novel combinations not previously available.

Open Access

Abstract

Clerodendrum thomsoniae Balf. plants untreated and treated with a 0.3 mg drench of ancymidol (a-cyclopropyl-a-(4-methoxyphenyl)-5-pyrimidmemethanol) flowered under a 12 hr photoperiod and were mostly vegetative under a 15 hr photoperiod. Initiation of flower parts was 8 days earlier in ancymidol treated than untreated plants. Although ancymidol hastened the initiation of flower parts, untreated plants flowered at nearly the same time as treated ones. The shoot apex remained vegetative and axillary buds flowered in treated and some untreated plants. In untreated plants, flower induction in the axillaries was apparent at 12 days and only sepal and petal primorida were present at 16 days after the initiation of the experiment when the plants were 9 cm tall. In treated plants, induction was apparent 4 days after treatment; flower development was accelerated; and at 16 days all flower parts were differentiating.

Open Access

Abstract

More rhizomes were initiated by plants of ‘Astrid’ chrysanthemum grown in short day and cool air temperature than in long day and warm air. Rhizome development was greatest, shoot growth was enhanced, and root length and dry weight increased with warm compared to cool soil temperature. Rhizomes grown at a cool soil temperature either in long or short days had the least cellular injury after exposure to –8°C.

Open Access

Abstract

The stems of 3 clones of Dianthus were studied at weekly intervals from August through November and the cold-hardiness as well as the peroxidase isoenzyme complement was determined. The hardening patterns showed indications of the typical plateau, this occurring at −10 to −14°G in November. The time of initiation of hardening correlated well with the winter-hardiness of the clones, the hardiest clone undergoing hardening 2 to 3 weeks before the tender clone. As determined by acrylamide gel electrophoresis of the stem extracts, the 2 winter hardy clones showed a gradual synthesis of 2 to 4 new peroxidase isoenzymes during the hardening period, whereas the tender clone showed only a relatively weak initiation of one isoenzyme. The formation of the new isoenzyme preceded the period of hardening by several weeks to more than a month, depending on the specific isoenzyme and the clone.

Open Access

Abstract

‘Dark Red Irene’ and ‘Princess Irene’ geraniums were subjected to low, medium, and high soil moisture regimes in the greenhouse for 10 weeks. A system was devised to maintain 3 moisture levels. Plant height, leaf area, and dry weight increased as soil moisture increased. Diameter of petioles and stems and thickness of leaves also increased as soil moisture increased. Number of xylem elements per unit area increased considerably in stems and petioles of plants grown in the high moisture regime, while phloem tissue was greater in plants grown in medium moisture. More vascular bundles were differentiated in leaves per unit as soil moisture decreased. ‘Princess Irene’ had fewer xylem and more phloem elements than ‘Dark Red Irene’, especially in plants grown in high soil moisture.

Open Access

Abstract

Two cultivars of Pelargonium hortorum Ait. were used to determine the effect of certain environmental conditions and cultural practices on the formation and development of oedema. High light intensity, low nutritional levels and high soil moisture content increased susceptibility of leaves to oedema. Severity increased when plants were subsequently exposed to environmental conditions that favored water absorption rather than transpiration. A study of stomatal behavior of oedematous leaves showed greater vapor diffusion resistance compared with normal leaves. The excess water in leaf tissues caused hypertrophy of some cells in the leaf which resulted in plugging the sub-stomatal chamber. Sometimes there was an increase in the size of epidermal cells adjacent to guard cells forcing them to close. The stoma was sometimes collapsed as a result of hypertrophy of surrounding cells. The differences in the susceptibility of the 2 cultivars to oedema under high soil moisture was due to differences in their internal structure and stomatal behavior.

Open Access

Abstract

Five cultivars of Pelargonium hortorum Ait. were used to determine the effect of soil and air temperatures, photoperiod, light intensity, soil water content, and cultivar response on the occurrence and severity of oedema. Oedema was most severe on the peripheral portions of the lower epidermis of the lower, older leaves of the plants. As the disorder progressed, the symptoms became prevalent over the entire lower epidermis. Symptom expression was similar in appearance on most of the cultivars, but the cultivars differed in their susceptibility. A continuously warm moist soil with humid cool night temperatures predisposed plants to oedema. Anatomically, hypertrophy of the spongy parenchyma cells into the sub-stomatal cavity resulted in the occlusion of the stomatal pore. In severe stages the spongy parenchyma cells divided periclinally and a periderm was differentiated which resulted in the raised macroscopic intumescences characteristic of oedema.

Open Access

Deformations consisting of longitudinal ridges in the rind of Citrus fruits have recently been found in Southern California Citrus groves. Here, we report the correlation between ridge formation and applications of chlorpyrifos (Lorsban, Dow Chemical Company, Midland, MI) during the feather-growth stage of bud break. All chlorpyrifos formulations resulted in significant ridging. Addition of agricultural oil and 2,4-D (2,4-dichlorophenoxyacetic acid (2,4-D) to chlorpyrifos resulted in the greatest ridging damage and widened the window of susceptibility by 2 weeks in 1988. In 1989, no significant difference was seen between treatments of chlorpyrifos, although all were significantly greater than the control. The susceptible stages of bud growth are described, as are the non-susceptible stages which precede and follow it. Floral buds in which carpels are initiating are susceptible to fruit ridging upon application with chlorpyrifos. These ridges are the result of an increase in cell size of the flavedo tissue which may be the result of a polyploid chimera.

Free access

Summer cover crop rotations, compost, and vermicompost additions can be important strategies for transition to organic production that can provide various benefits to crop yields, nitrogen (N) availability, and overall soil health, yet are underused in strawberry (Fragaria ×ananassa) production in North Carolina. This study was aimed at evaluating six summer cover crop treatments including pearl millet (Pennisetum glaucum), soybean (Glycine max), cowpea (Vigna unguiculata), pearl millet/soybean combination, pearl millet/cowpea combination, and a no cover crop control, with and without vermicompost additions for their effects on strawberry growth, yields, nutrient uptake, weeds, and soil inorganic nitrate-nitrogen and ammonium-nitrogen in a 2-year field experiment. Compost was additionally applied before seeding cover crops and preplant N fertilizer was reduced by 67% to account for organic N additions. Although all cover crops (with compost) increased soil N levels during strawberry growth compared with the no cover crop treatment, cover crops did not impact strawberry yields in the first year of the study. In the 2nd year, pearl millet cover crop treatments reduced total and marketable strawberry yields, and soybean treatments reduced marketable strawberry yields when compared with the no cover crop treatment, whereas vermicompost additions increased strawberry biomass and yields. Results from this study suggest that vermicompost additions can be important sustainable soil management strategies for transitional and certified organic strawberry production. Summer cover crops integrated with composts can provide considerable soil N, reducing fertilizer needs, but have variable responses on strawberry depending on the specific cover crop species or combination. Moreover, these practices are suitable for both organic and conventional strawberry growers and will benefit from longer-term studies that assess these practices individually and in combination and other benefits in addition to yields.

Full access