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  • Author or Editor: R.H. Merritt x
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Abstract

Geranium seedlings (Pelargonium × hortorum L.H. Bailey ‘Mustang’) were greenhouse-grown at a plant density (PD) of 85, 170, 255, or 340 plants/m2 for two time periods (21 to 34 days and 35 to 62 days from sowing). There was a positive linear regression between PD and crop productivity (CP), expressed as g dry matter/day per m2; between PD and crop productivity efficiency (CPE), expressed as percent of energy in the photosynthetic photon flux (PPF) incident on the crop that is stored in crop dry matter as energy of combustion; and between PD and leaf area index (LAI) for both time periods. Plant top dry weight, leaf area, length of longest petiole, and main stem length and height were not affected by PD at 35 days from sowing. However, at 63 days from sowing there was a negative linear regression between PD and both plant top dry weight and main stem length, and a positive linear regression between PD and both plant height and length of the longest petiole.

Open Access

Abstract

Calcium deficiency symptoms of heartleaf philodendron (Philodendron scandens ssp. oxycardium) were reported to occur first on the vine's basal leaves, with the tip or uppermost leaves the last to develop symptoms (1). This pattern of symptom development was interpreted to indicate that philodendron was an exception to the generalization that Ca is immobile in plants, i.e., in philodendron, Ca was translocated from basal to upper leaves (5). Since Ca deficiency symptoms occur in meristematic areas (such as shoot and root tips), Ca is considered immobile in plants (2). Thus, the report of Ca deficiency symptoms on basal leaves of philodendron (1) was indeed exceptional. Unfortunately, there was no report of the recovery of the deficient plants when fertilized with Ca, nor any Ca analysis of philodendron tissue, to confirm that Ca deficiency was the cause of the observed symptoms (1) and to support the conclusion that Ca was mobile (5). The purpose of this study was to produce Ca deficiency symptoms in heartleaf philodendron to determine if Ca deficiency symptoms occur on basal leaves, as originally reported (1).

Open Access

Abstract

Two primary purposes of education are to satisfy the quest for knowledge and to provide educated and trained persons to serve the needs of society. These purposes also constitute an important part of the mission of a horticulture teaching program. In recent years, this mission has become more difficult to achieve, being challenged by declining enrollments, reallocation of positions, operating resources for teaching, inadequate facilities, and the diminishing half-life of new knowledge brought about by rapid advances in science and technology. The challenge also comes from institutional and societal pressures to look beyond disciplinary boundaries in both teaching and research.

Open Access

Abstract

Static solution culture systems are widely used in plant research and for teaching demonstrations of plant nutrient deficiency symptoms. Numerous systems have been described (1,2) including one (3) constructed of readily available materials. Reported here is another design for a static solution culture system built of readily available components. This system is characterized by a) low cost, b) simplicity, c) easy assembly, d) potential for variable spacing of culture vessels, e) identical aeration rate for each vessel without individual air flow valves, and f) aeration from the top of the culture vessel rather than the bottom, eliminating drainage through aeration lines should the air supply fail.

Open Access

Abstract

Seedlings of Begonia × semperflorens-cultorum Hort. ‘Scarletta’ were grown in a greenhouse at a plant density of 193 plants/m2. Crop productivity (grams of dry matter produced per day per square meter of crop) and crop productivity efficiency (percentage of the photosynthetic photon flux incident on the crop that is stored in the form of crop dry matter as energy of combustion) did not increase when the photoperiod was extended from 9 to 13 hr with incandescent lights. However, stem and petiole length did increase under 13- compared to 9-hr photoperiods. Crop productivity of begonia was less than maximum values reported for some other bedding plants. However, when crop growth was expressed in terms of fresh weight rather than dry weight, begonia crop growth exceeded that reported for other bedding plants. This increased growth seemed to be due to the low dry weight to fresh weight ratio in wax begonia of 0.03.

Open Access

Aquilegia cultivars `Songbird Bluebird', `Songbird Robin', `Dove Improved', `Colorado Violet/White' and five cultivars from new experimental genetic lines (`Red and White', `Rose and White #1', `Rose and White #2', `Scarlet and Yellow' and `White') will flower without vernalization, but little is known of their response to light or plant growth regulators. Plants were started from seed on 5 Jan. 1999 and grown in either natural light or 33% shade, and treated with gibberellins (GA4/7) at the seven-leaf stage. Flowering time, number of flowers/plant, and plant height were evaluated through 31 May 1999. All five cultivars from the new genetic lines bloomed during the study. `White', grown in shade and treated with GA4/7, bloomed 2 weeks earlier (115 days) than untreated plants grown in natural light (130 days). `Songbird Robin', treated with GA4/7, bloomed in 146 days, and was the only other cultivar to bloom. Flower numbers were greater in natural light than in 33% shade. GA4/7 increased flowering for four of five cultivars, in the new genetic lines, grown in natural light. In shade, GA4/7 increased flowering for three of five cultivars. Height response to GA4/7 was significant in both natural light and 33% shade. Four of the five cultivars in the new genetic lines were taller when treated. All five of these cultivars were taller when grown in natural light verses 33% shade. `White' and both `Rose and White' cultivars were consistently taller, bloomed earlier and were more floriferous when treated with GA4/7.

Free access

A heat-unit model was established for tracking the development of geranium, based on experimental data collected at UC Davis and Rutgers Univ. The temperature thresholds for initiating development and heat-unit benchmarks needed to accomplish each phenostage are parameters in this model. The methods of estimating these parameters were proposed and tested with the observed data. The model worked well during either vegetative or reproductive stages, but failed to predict the initiation of flowers, suggesting that factors other than only temperature drive the flower initiation process. With this model crop development characterized by a series of specific morphological events can be tracked and predicted under various temperature regimes, so that crop timing can be more precise.

Free access