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  • Author or Editor: R. D. Wright x
  • Journal of the American Society for Horticultural Science x
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Stem cuttings of Blue Rug juniper (Juniperus horizontalis Moench `Wiltonii'), `Hino-Crimson' azalea [Rhododendron (Lindl.) P1anch `Hino-Crimson'], and `Helleri' holly (Ilex crenata Thunb. `Helleri') were propagated in 1 peat: 1 perlite (v/v) at one of five moisture levels based on medium dry weight (125%, 250%, 375%, 500%, or 625%). Cutting survival and percentage of rooted cuttings were highest at the highest medium moisture level in all three species. Incidence of cutting basal rot was not directly related to medium moisture level, but more to the growth stage of the stock plant. Midday xylem water potential (ψ) of cuttings for each species was highest in the wettest propagation medium and lowest in the driest medium. During propagation, stem cutting ψ below - 2.0 MPa occurred even in the wettest medium tested, and frequently reached - 4.0 MPa in cuttings in the driest treatment (125%). Basal water uptake by cuttings was highest in the wettest medium moisture level. Water uptake was highest during the first few days after insertion, and thereafter decreased until root emergence.

Free access

Abstract

Multiple branched liners of ‘Helleri’ holly growing in a pine bark medium were fertilized at the beginning of active root growth at 300, 400, 500, or 600 ppm N with a 20N−8.7P−16.7K water soluble fertilizer. One week later, one half of the plants were fertilized again. The treatments were repeated during the next 2 periods of root growth which occurred about 6 weeks apart. The above soluble fertilizer was applied weekly at 300 ppm N to the control plants. Shoot growth of plants fertilized twice at 500 ppm N was comparable to growth of the control plants. Further, these plants received 44% less fertilizer and utilized 17.6% more of the total fertilizer applied. Extract nutrient and soluble salt levels were high during root growth and low during shoot growth except for the control plants, indicating the plant's need for fertilizer predominates during periods of active root growth.

Open Access

Abstract

The pour-through (PT) method of nutrient extraction, which involves pouring water on the container media surface and collecting the extract (leachate), was compared to the saturated soil extract (SSE) method for a 100% pine bark medium at container capacity (102% gravimetric moisture). The SSE and PT correlation coefficients, respectively, were 0.99 and 0.94 for N, 0.99 and 0.97 for P, 0.99 and 0.93 for K, and 0.99 and 0.98 for pH. As container media moisture levels increased from 50 to 102%, the PT and SSE soluble salt levels increased 1.5 and 1.6 times, respectively, while nitrate levels increased 1.7 and 1.6 times, respectively. The volume of water applied for the PT was varied from 40 to 100 ml and did not result in extraction of different levels of N, P, K, Ca, or Mg. These data indicate the PT is an alternative to the SSE for nutrient extraction from a pine bark medium.

Open Access

Abstract

The response of cape primrose (Streptocarpus) plants to external N application is dependent on growth media only in terms of response magnitude. A 2.0% to 2.9% tissue N level in either sand or bark media maximized shoot dry weight, the number of potential flowers, and the quantity and quality of plantlets regenerated during subsequent asexual propagation. In sand, 2.9% tissue N was below the level required for maximum leaf elongation and resulted in a desirable restriction of the primary leaf (phyllomorph). Tissue N levels that either exceeded or lagged behind the optima were often detrimental to plant aesthetics, and wasteful where luxuriant tissue levels did not affect the measured characteristics.

Open Access

Abstract

Rooted stem cuttings of Ilex crenata Thunb. ‘Helleri’ were grown in a series of experiments for 3 or 6 weeks at day/night temperatures ranging from 6°/2° to 26°/22°C. Percentage of tissue N increased over time at all temperatures but at progressively slower rates as temperature decreased. Temperatures of 18°/14° or less prevented visible shoot elongation, although plant dry weights increased at all temperatures. Percentage of dry weight K increased and P, Ca, Mg, Mn, and Zn decreased with time for plants grown at 10°/6°, 14°/10° and 18°/14°, whereas the total amounts of each nutrient per plant increased. Nutrient content increased at greater rates as temperature increased. Nitrogen accumulation data were used to develop a method of timing fertilizer application in the fall. The proposed procedure ensures adequate nutrient accumulation to support vigorous spring growth without jeopardizing proper cold acclimation in the fall

Open Access

Abstract

Pine bark was shown to adsorb 1.5 mg of N/g of bark when NH4 solutions were leached through the bark. Increasing pH of bark increased adsorbed NH4. At pH 3.3, only NH4 was adsorbed to bark particles when a fertilizer solution containing NH4, Ca, K, and Mg was applied. However, adsorption of NH4 and other cations increased as pH was increased from 3.8 to 5.8. These data indicate that 2 types of sites exist for the adsorption of NH4 to pine bark. One site is effective at lower pH; the other is active as pH increases. Daily application of 2.5 cm of water containing 50 ppm NH4 required 20 days for equilibration to occur so as to satisfy all binding sites. Thus, incorporation of NH4 into a pine-bark medium prior to planting may be advisable to prevent low N levels from occurring in the container solution due to NH4 binding when plants are first planted and fertilized.

Open Access