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  • Author or Editor: B. K. Harbaugh x
  • Journal of the American Society for Horticultural Science x
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Abstract

Various rates, types, and formulations of controlled-release fertilizers were evaluated as potential components in a trickle irrigation production system for spray chrysanthemums (Chrysanthemum morifolium Ramat.). Optimum rates of total-N, with 34 kg N/ha as soluble 6-2.6-5 (N-P-K) and the remainder as 14-6.1-11.6 Osmocote, were estimated to be from 489-501 kg per planted hectare in 2 tests. Other formulations or ratios of Osmocote and urea formaldehyde fertilizers at similar rates did not improve production or were not comparable to Osmocote 14-6.1-11.6 or to the commercial practice of weekly overhead liquid fertilization. A water savings of 70-80% was estimated with the controlled-release fertilizer-trickle irrigation system compared to overhead irrigation, while yields (marketable stems and height) were similar to those produced with overhead-liquid fertilization practices.

Open Access

Abstract

Plants of Philodendron scandens subsp. oxycardium (Schott) Bunt. were exposed to ethylene-air mixtures at various temperatures and levels of light and CO2. Plants held in ethylene (2.5 to 10μl/liter air) abscised leaves and stipules, developed chlorotic foliage, and grew poorly. As the levels and duration of exposure to ethylene increased, the rate of leaf abscission increased. Plants exposed to 5μl ethylene/liter air at 23.5°C for 3 days in light abscised more than 50% of their leaves, whereas plants similarly handled but held in darkness lost 20%. At a given level of ethylene, the lower the temperature the fewer the number of leaves abscised. Plants held at 27° at 10 μl/liter air had total leaf abscission. Plants held in ethylene with 5% CO2 or with lanolin-coated leaves abscised fewer leaves than plants without added CO2 or non-coated leaves.

Open Access

Abstract

Geranium seedlings were exposed to various levels of ethylene (0–10 µl/liter air) at 23°C for 2 and 5 days in light. Seedlings held in ethylene for 2 days developed more chlorotic leaves and did not grow as well as seedlings held in air. Seedlings exposed to ethylene for 5 days abscised leaves, whereas those exposed for 2 days did not. Seedlings exposed to ethylene (1 µl/liter air) at 23° for 3 days in dark had more chlorotic leaves and did not grow as well as seedlings exposed to ethylene in light. Seedlings held in air in darkness had more chlorotic leaves than seedlings held in air in light. Seedlings held in air in the laboratory grew as well as seedlings held in the greenhouse. Seedlings exposed to ethylene (1 µl/liter air) for 3 days in dark retained more chlorophyll and had better growth at low temperatures (4.5°, 10°) than those exposed at higher temperatures (15.5°, 23°). Seedlings held in air at all temperatures for 3 days had similar chlorophyll levels and growth patterns. Temperature was negatively correlated with loss of chlorophyll and plant dry weight and positively correlated with number of chlorotic leaves of seedling held in darkness for 7 days.

Open Access

Abstract

Experiments were designed to develop information on commercial production systems for Episcia cupreata (Hook.) Hanst. (flame violet) encompassing nutrition, propagation, light intensity, and insect pest management. A 200–250 ppm N and 150 ppm K solution applied at a rate of 50 ml/10-cm pot per week provided adequate nutritional requirements for these major elements. Propagation techniques involving combinations of rooted or unrooted plantlets 5–13 cm in canopy diameter provided crop turnover rates from 4 to 12 weeks for production in 10-cm pots. Optimum light intensity was established at 17–22 klx. Acephate and oxamyl eliminated mealybugs (Ferrisia virgata) on Episcia plants and were not phytotoxic to the foliage.

Open Access

Abstract

A study was conducted to investigate environmental factors which affect leaf water potential (LWP) response of chrysanthemums (Chrysanthemum × morifolium Ramat). Meteorological parameters, including air temperature (TEMP), relative humidity (HUM), total solar radiation (RAD), and photosynthetically active radiation (PAR) were measured simultaneously as LWP determinations were made diurnally for plants grown with 5 different irrigation rates. Stepwise multiple regression analyses using the meteorological parameters as independent variables and LWP as the dependent variable showed that models developed for each irrigation rate included TEMP, HUM, and PAR as statistically significant (P = 5%) independent variables. Coefficients of determination (R2) for the models ranged from 0.83–0.87. A combined model, including irrigation rate (R) as an independent variable along with the meteorological parameters, revealed that TEMP, PAR, HUM, and R were statistically significant at P = 1% and had an R2 = 0.84. Results reveal environmental factors which must be considered in studies involving LWP measurements for chrysanthemums in order to avoid misinterpretation of data.

Open Access