Geraniums (Pelargonium × hortorum L.H. Bailey `Yours Truly') were grown in a glasshouse from 15 Mar. to 9 May as single pinched plants in a growing medium with a bulk volume of 1.3 liters per 15cm diameter standard plastic pot. Plants received constant fertigation with N at 300 mg·liter-1 from 20N-4.4P-16.6K with leaching fractions (LFs) of ≈ 0, 0.1, 0.2, and 0.4. The LF is the volume of solution leached from the container divided by the volume of solution applied to the container. There were 24 irrigations during the study. Plants with LFs of 0.2 and 0.4 had 46% larger leaf area, 40% more shoot fresh mass, and 37% more shoot dry mass than plants with LFs of 0 and 0.1. By week 5, the leachate electrical conductivity (EC) at 25C for LFs of 0.1,0.2, and 0.4 had increased from ≈ 3 dS·m-1 initially to 12, 8, and 4 dS·m-1, respectively. At harvest, the EC of a saturated medium extract (ECe) was 7, 4, 3, and 2 dS·m-1 for LFs of 0, 0.1, 0.2, and 0.4, respectively. At harvest, medium EC, with LFs of 0.1, 0.2, and 0.4 was 47% 68%, and 60% less in the lower two-thirds of the pot than in the upper third. With a LF of 0, the medium EC, was `not lower in the bottom of the pot. With fertigation N at 300 mg·liter-1, minimizing the LF substantially reduced growth of container-produced geraniums. In addition to specifying LF, the number of container capacities leached per week, termed the leaching intensity (LI), should be calculated for container leaching studies. In two studies, the LFs may be the same yet the LIs can be very different.
Poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch `V-14 Glory') were grown in a greenhouse for 70 days in 1.3 liters of medium (13 cm deep in 15-cm pots) with a leaching fraction (LF) of ≈ 0, 0.1, 0.2, or 0.4. Plants were fertigated with 300 mg N/liter from 20 N-4.4P-16.6K. The electrical conductivity (EC) of the fertigation solution was 2.1 dS·m-1. The leachate EC increased from 2 dS·m-1 initially to plateaus of ≈ 6, 9, and 15 dS·m-1 for LFs of 0.4, 0.2, and 0.1, respectively. Poinsettia height, shoot fresh and dry mass, and leaf and bract areas were not significantly different among the LF treatments. Leachate pH decreased from 6.1 initially to 5.1 at the end, but there was no significant difference among the LF treatments. The EC of a saturated medium extract (ECe) was between 17% and 48% higher in the lower third of the medium than in the middle third. The difference was greater with a lower LF. The EC, was 8.9, 7.3, 5.2, and 3.4 dS·m-1 in the lower third of the pot for a LF of 0, 0.1, 0.2, and 0.4, respectively. Under conditions of this study, container poinsettias required no leaching.
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.
Single-pinched `Yours Truly' geranium (Pelargonium × hortorum) were greenhouse grown in 15-cm diameter pots. They received constant liquid fertigation with a modified Hoagland solution #1 at 0.25, 0.5, 1.0, and 1.5 strength. The 1.0 strength Hoagland solution contained 210 mg/L NO3-N and 31 mg/L P. Leaching fractions (LFs) were 0, 0.2 and 0.4. The total P applied via fertigation ranged from 33 mg at 0 LF and 0.25x Hoagland to 407 mg at 0.4 LF and 1.5x Hoagland. The leachate P concentration ranged from <5 mg/L to -60 mg/L. The P concentration in the recently matured leaves was in the acceptable range for all treatments. We were able to recover 90 to 99% of the applied P by analyzing the shoots, soilless medium, and leachate. Only 4% of the recovered P was in the leachate for plants receiving 0.5x Hoagland and a 0.2 LF. However, these plants were equal in yield to plants receiving higher fertigation rates and higher LFs.
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.
Geranium `Yours Truly' in 15-cm diameter plastic pots were greenhouse-grown as single pinched plants in a completely randomized design. Plants were irrigated with 300 mg/liter N from 20N-4.4P-16.6K with leaching fractions (LF) of 0, 0.1, 0.2, and 0.4. There were 24 irrigations during the 8-week study. Plants with LF of 0.2 and 0.4 had 46% greater leaf area, 40% greater top fresh weight, and 37% greater top dry weight than plants with LF of 0 and 0.1. By week 5 the leachate electrical conductivity (EC) for LF of 0.1, 0.2, and 0.4 had increased from about 3 dS/m initially to 12, 8, and 4 dS/m, respectively. At harvest, medium ECe was 7, 4, 3, and 2 dS/m for LF of 0, 0.1, 0.2, and 0.4, respectively. At harvest, medium pH was the same in the top, middle, and bottom thirds of the pot. At harvest medium ECe with LF of 0.1, 0.2, and 0.4 was 47, 68, and 60% lower in the bottom two-thirds of the pot than in the top third. With a LF of 0 the medium ECe was not lower in the bottom of the pot. Minimizing the LF for potted geraniums substantially reduced plant growth.
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.
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).
A sample of clinoptilolite with an exchangeable K, Na, Ca and Mg content of 160.0, 33.5, 18.7, and 0.4 meq/100 g was evaluated as a slow-release К fertilizer by leaching and growth studies of Chrysanthemum morifolium, Ramat. Potassium release from an amended potting medium indicated that clinoptilolite did not behave like a soluble K source but was very similar to slow-release fertilizers. A single application of 50 g clinoptilolite per 1.5 liters of potting medium produced 3-month chrysanthemum yields equal to those obtained with a daily irrigation with 234 ppm K.