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  • Author or Editor: D. R. Johnson x
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The influence of N and K rates in Hoagland's nutrient solution on Jalapeño pepper (Capsicum annuum L.) plant growth and pod production was determined on greenhouse-grown plants in sand culture. Varying the rates of N (1 to 30 mm) and K (1 to 12 mm) in Hoagland's solution identified optimum concentrations for Jalapeño plant growth and pod production. Two experiments were conducted to determine Jalapeño pepper sensitivity to differential fertilization. In the experiment seeded in April, nutrient treatments began at transplanting, and in the one seeded in May, treatments began after all plants had flower buds and half had flowered. Biomass and pod production per plant responded curvilinearly to N rate in both experiments. Optimum N rate for pod yield was 15 mm. Nitrogen rate affected pungency of pods only in the first experiment, with 1 mm N reducing capsaicin levels in fruit compared to other N rates. Biomass, fruit count, and fruit weight per plant increased linearly with increasing K rate in the first experiment and curvilinearly with K rate in the second experiment. The optimum K rate for pod yield was 6 mm. Potassium rates did not affect pod pungency. Jalapeño peppers grown in sand culture required 15 mm N and at least 3 mm K for optimum pod production.

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Abstract

The response of fruit size and fruit size distribution was studied in four peach (Prunus persica L. Batsch.) cultivars (May Crest, June Lady, Elegant Lady, O’Henry) ranging in maturity date from late May to early August (75 to 150 days after bloom). Mature, open-vase trees were thinned to fruit levels ranging from 150 to 2200 fruit per tree. The slopes of the linear relationships between fruit weight and fruit number per tree were consistent among cultivars, but their y-intercepts increased proportionate to maturity date. The standard deviation of individual fruit weights tended to decrease with increasing fruit number per tree and increased with later-maturing cultivars. However, the coefficient of variation remained nearly constant among cultivars. Mean fruit weight generally dropped off with successive harvests, especially on trees with heavy fruit loads. Heavy fruit loads also delayed maturity in all four cultivars. This study measured the variation of fruit weight response to thinning, information that is needed for a detailed economic analysis of thinning to different fruit loads.

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.

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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

Abnormal needle tip curling was induced by low humidity in 4 half-sib families of loblolly pine (Pinus taeda L.) grown in a growth chamber. The injury developed on new growth on both 12-week-old and 1-year old seedlings when plants were maintained under 30% ± 5% relative humidity with a 16-hour photoperiod, 23°C light period and 17° dark period. Very little injury developed on plants maintained at 70% ±5% relative humidity. Significantly more needle tip curling occurred on seedlings grown from seed collected in Texas than in seed collected from Virginia.

Open Access

Abstract

Five plant species [burford holly (Ilex cornuta Lindl. and paxt. ‘Burfordii’) golden-rain tree [Koelreuteria elegans (Seem. A.C. Sm.], ligustrum (Ligustrum japonicum Thunb.), hibiscus (Hibiscus rosa-sinensis L.), and podocarpus (Podocarpus macrophyllus Thunb.)] were arranged in a 5 × 5 × 5 factorial experiment and sprayed with 4 pesticides (dimethoate, dicofol, malathion, oxydemeton methyl) and water alone, as well as 4 chemicals [ancymidol, ethephon, gibberellic acid (GA3)] and water alone. Growth regulators increased pesticide phytotoxicity ratings, whereas the antitranspirant had no effect on phytotoxicity ratings.

Open Access

One of the deterrents to the commercial adoption of controlled-environment agriculture (CEA) on a broad scale is the significant energy cost for lighting and thermal environmental control. Advances in energy conversion technologies, such as internal combustion engines (ICs), microturbines and fuel cells, offer the potential for combined heat and power (CHP) systems, which can be matched with the needs of CEA to reduce fossil-based fuels consumption. A principal concept delineated is that an integrated entrepreneurial approach to create business and community partnerships can enhance the value of energy produced (both electrical and heat). Energy production data from a commercial dairy farm is contrasted with energy use data from two greenhouse operations with varying energy-input requirements. Biogass produced from a 500-cow dairy combined with a 250-kW fuel cell could meet nearly all of the energy needs of both the dairy and an energy-intensive 740-m2 CEA greenhouse lettuce facility. The data suggest CEA greenhouses and other closely compatible enterprises can be developed to significantly alter agriculture, as we have known it.

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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

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

Increased soil moisture stress reduced growth and transpiration rate of Ficus benjamina. Leaf drop during indoor phase was greater for plants previously watered during production at 3 day intervals than for plants grown under the 6- and 9-day water regimes.

Open Access