E. Jay Holcomb

A practical method for the production of flowering Easter lilies from callus cultures

Abstract Callus cultures were established from immature leaf explants of Easter lily ( Lilium longiflorum Thunb. cv. ‘Nellie White’). These callus cultures were induced to undergo organogenesis within 3 weeks upon subculture to medium containing 0.1 mg l −1 of both 2,4-dichlorophenoxyacetic acid and 6-benzylaminopurine. The regenerated plantlets were acclimatized under a mist and transferred to greenhouse conditions at a 100% success rate. Plants exposed to supplemental lighting produced an average of four flowers per plant, were 20 cm shorter and flowered six and a half weeks sooner than plants maintained under normal day length conditions, where only 63% of the plants flowered. On average, plants supplied with supplemental lighting required 29 weeks (8 weeks of acclimation, 9 weeks in 15 cm pots under normal greenhouse conditions, and 12 weeks under supplemental lighting) from the time of establishing in the greenhouse to full bloom. The number of abnormal plants observed was less than 2%. Maintaining plants in 6 cm × 4 cm × 5.5 cm growing trays produced miniature Easter lily plants, each with a single flower.

Potassium release from selected slow‐release fertilizers 1

Abstract Potassium (K) release rate from Osmocote 14–6.3–11.6 (N‐P‐k), MagAmp 7–18–5, Choice 10–4.3–8.3, Scotts 21–3–5.8 and Unimix 10–8.7–4.2 was determined. During the 63‐day experiment Osmocote and Scotts had relatively linear release rates while the release rate from the other fertilizers was initially rapid and decreased over time.

Correlation among soil test values and elemental composition of chrysanthemums

SummaryChrysanthemum morifolium Ramat. plants were grown in a soil mix fertilized daily with a balanced solution containing N, P, K, Ca, and Mg at 4 rates which were 0.5, 1, 2, and 4 times. At the end of 4 weeks of vegetative growth, the above-ground portions of the plants were analyzed for elemental content, and the soil mix was analyzed by 3 soil testing procedures. The N, P, and K contents of chrysanthemum were positively correlated with the reported values of these nutrients in the soil as determined by the Spurway, Penn State, and Intensity-Balance soil tests. Magnesium, as in the Penn State and Intensity-Balance soil tests, was negatively correlated with plant Mg content; however, Ca was not significantly correlated with plant Ca in the Penn State test and negatively correlated in the Intensity-Balance test. The magnitude of the correlation coefficients between nutrient content of the plants, and the soil test value of the nutrient by all three soil tests were similar indicating that all three soil tests can be used.

A technique for determining potassium release from a slow‐release fertilizer 1

Abstract A new technique was utilized to determine the rate of potassium release from a slow‐release fertilizer. The technique is based on diffusion of the potassium ion into a saturated capillary mat followed by extraction and analysis of the solution pressed from the capillary mat. The technique demonstrated that K was released at a rate similar to that reported by another researcher. The major advantage of this technique is the simple readily available equipment needed for solution extraction.

In situ determination of electrical conductivity of potting media using time domain reflectometry

Abstract The possibility of measuring both the volumetric water content (ν θ) and bulk electrical conductivity (ECb) of media using a single instrument makes time domain reflectometry (TDR) invaluable for greenhouse potting media ν and ECb determination. Laboratory experiments in three different potting media instrumented with triple‐wire TDR probes were performed to calibrate the TDR system for the determination of potting media water electrical conductivity (ECw). The performance of the TDR for in situ determination of ECw, using the experimentally‐determined conductivity model, was investigated using packed columns of potting media. Linear relationships between the ECb‐ECw data were found for all the tested media at the three water contents (0.30, 0.36, 0.45 cm3cm‐3) for four solute concentrations ranging from 1.481 to 3.797 dS m‐1. Linear regression coefficient of determination, r2, of between 0.97 and 0.99 were achieved. Calibration accuracies ranged from 94% to 98% for ECwpredictions. Results indicate that TDR is a useful technique for the accurate determination of potting media Ecb. TDR allows determination of ECw, from the measured ECb and θν, to be made quickly and simultaneously using a single and relatively inexpensive probe combined with the TDR cable tester.

Growth of bedding plants and poinsettias in mineral wool and mineral wool/peat substrates

Abstract Studies were conducted to ascertain the suitability of mineral wool (MW), either alone or in combination with sphagnum peat moss, as a substrate for potted greenhouse plants. Two types of hydrophyllic mineral wools, cleaned mineral wool (CMW) and uncleaned mineral wool (UMW), were used. Unamended CMW had a low bulk density, excellent water holding capacity, good aeration, but a high pH. Once peat moss was added to the CMW, bulk density remained low, water holding capacity remained good, and the pH dropped to a more suitable level. Unamended UMW had a high bulk density, good water holding capacity, poor aeration, and a high pH. Once peat moss was added to UMW, bulk density decreased, water holding capacity remained good, aeration increased, and the pH decreased to a more optimal level. CMW and UMW, were used unamended, as well as amended with 25%, 50%, and 75% peat moss. Two bedding plants, Impatiens walleriana ’Dazzler Violet’ and Begonia semperflorens ’Whiskey’ were grown for six and nine weeks ...

Chrysanthemum and poinsettia growth in coal gasification slag amended media

Abstract Coal gasification slag is a by‐product of the power industry that may prove useful to the horticultural industry as a component of growing media. The objectives of this research are to determine if suitable crops of chrysanthemum and poinsettia can be produced in media of slag alone or in combination with moss peat. Chrysanthemums and poinsettias were grown in slag or slag mixes in an ebb and flow irrigation system with a complete nutrient solution being recycled. Slag alone had a high bulk density and high pH, but adding 50% by volume peat decreased bulk density and pH so that an acceptable growing mix resulted. Weight of plant shoots grown in slag was lower than for plants that were grown in slag mixes. Weight of plants in slag mixes was similar to the peat‐perlite control. Plants grown in slag or slag mixes generally were low in phosphorus (P) and manganese (Mn) and high in boron (B). The slag mixes seem to remove P and Mn from the fertilizer solution while releasing B and to some extent calci...