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J. Vlamis and Robert D. Raabe

Abstract

The new growth of manzanita (Arctostaphylos densiflora M.S. Baker and other Arctostaphylos spp.) grown in a nursery in a mix of 2 fir bark : 1 sand (v/v) in plastic containers remained very small and showed some necrosis. Tissue analysis indicated a possible copper deficiency. The addition of 8 mg of copper as copper sulfate per 15 cm pot produced normal growth. The application of boron or calcium was not effective in controlling the problem.

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John M. Englert, Gary D. Coleman, Tony H.H. Chen, and Leslie H. Fuchigami

A 32kDa bark storage protein (BSP) which accumulates in the fall and is degraded in the spring has been identified in Populus deltoides bark. The BSP gene has been shown to be regulated by short day (SD) photoperiod (8 h). The physiological condition of the plant and the environmental factors necessary for the degradation and retranslocation of BSP are of considerable interest for determining the role of this protein in the remobilization of nitrogen in trees.

Poplar plants were placed in a SD growth chamber for 4 or 7 weeks to induce growth cessation (bud set) or dormancy, respectively. BSP accumulated to high levels in bark tissues after 3 weeks SD and remained high through 7 weeks SD. Plants in which growth had stopped (4 weeks SD), or in which dormancy (7 weeks SD) was broken with hydrogen cyanamide (0.5 M) or chilling (4 weeks 0C) broke bud within 1 week of being placed into long day (LD) conditions. Dormant plants which were not chilled broke bud after 3 weeks LD. BSP levels decreased around the time of budbreak, suggesting that the degradation of BSP is dependent on the need for a nitrogen sink, ie. budbreak and new shoot growth.

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Thomas Yeager, Ed Gilman, Diane Weigle, and Claudia Larsen

Columns (4 × 15 cm) of a pine bark medium amended with the equivalent of 4.2 kg per cubic meter of dolomitic limestone and either 0, 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde (38% N) per cubic centimeter of medium were leached daily with 16 ml of deionized water (pH 5.5). Leachate total N, NO3 --N and NH4 +-N concentrations were determined on day 1, 3, 5, 7, 14, 28, 49, 91, 133, 203, 273 and 343. Leachate total N ranged from 600 ppm on day 1 for the 9.5 mg treatment to 4 ppm on day 273 for the 2.4 mg treatment. Leachate NH4 +-N concentrations ranged from 38 ppm c4 day 3 for the 9.5 mg treatment to less than 1 ppm on day 7 for the 2.4 mg treatment and were less than total N concentrations at each sampling time. Leachate NO3 --N was not detectable during the experimental period. Eleven, 16, 20 and 25% of the applied N leached from the columns amended with 2.4, 4.7, 7.1 or 9.5 mg of urea-formaldehyde per cubic centimeter of pine bark, respectively, during the 371 day experiment.

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John D. Lea-Cox and Irwin E. Smith

Pine bark is utilized as a substrate in citrus nurseries in South Africa. The Nitrogen (N) content of pine bark is inherently low, and due to the volubility of N, must be supplied on a continual basis to ensure optimum growth rates of young citrus nursery stock. Three citrus rootstock (rough lemon, carrizo citrange and cleopatra mandarin) showed no difference in stem diameter or total dry mass (TDM) when supplied N at concentrations between 25 and 200 mg ·l-1 N in the nutrient solution over a 12 month growing period. Free leaf arginine increased when N was supplied at 400 mg·l-1 N. The form of N affected the growth of rough lemon. High NH4-N:NO3-N (75:25) ratios decreased TDM when Sulfur (S) was absent from the nutrient solution, but not if S was present. Free arginine increased in leaves at high NH4-N (No S) ratios, but not at high NH4-N (S supplied) ratios. Free leaf arginine was correlated with free leaf ammonia. These results have important implications for reducing the concentration of N in nutrient solutions used in citrus nurseries and may indicate that higher NH4-N ratios can be used when adequate S is also supplied.

Free access

Alex X. Niemiera, Ted E. Bilderback, and Carol E. Leda

Pine bark (PB), either unamended or amended with sand (S) at 9 PB: 1 S or 5 PB:1 S (v/v), was fertilized with solutions of 100,200, or 300 mg N/liter solution and tested for N concentration using the pour-through method (PT). PB, 9 PB: 1 S, and 5 PB: 1 S had porosities of 84%, 75%, and 66%, respectively. PT NO3-N concentrations, obtained via PT, of the 5 PB:1 S substrate were 43%,28%, and 15% higher than PB NO3-N values for the 100,200, and 300 mg·liter-1 treatments, respectively. Differences in N concentration obtained with PT can be attributed to substrate physical characteristics. Based on the results, data for PT should be interpreted with regard to substrate porosity.

Open access

Alexander X. Niemiera and Robert D. Wright

Abstract

Pine bark-filled containers were subjected to 10°, 20°, 30°, or 40°C for 24 days and fertilized periodically with 210 ml of a solution containing 100 ppm NH4-N. Every 6 days, medium solutions were tested for NH4-N and NO3-N concentrations and a NO3-N accumulation rate (NAR) was determined. Medium solution NH4-N concentrations were lower at 20° and 30° than at 10° and 40°, while those at 40° were considerably greater than at other temperatures and increased over time. In general, medium solution NO3-N concentrations at 10°, 20°, and 30° were comparable and higher than at 40°. Over time, the general order of NAR was 20° = 30° > 10° > 40°.

Free access

M. Pilar Bañados, Gary D. Coleman, and Tony H. H. Chen

In poplar (Populus deltoides) a 32kDa bark storage protein (BSP) accumulates during the fall, and is a major form of stored nitrogen during overwintering. This protein is induced by short-day (SD) photoperiod and may play an important role in nitrogen cycling in the plant. To determine the effect of plant nitrogen status upon BSP gene expression, poplar plants were grown in controlled environmental chambers under either SD or long-day (LD) photoperiods and watered with either 5, 10, 50, and 100 mM NH4NO3 for four weeks. [15N]-NH4NO3 was applied during the first and third weeks. SDS-PAGE and western blot analysis were used to detect the relative amounts of BSP. RNA gel blot analysis was used to determine the changes in BSP gene expression. BSP accumulation was enhanced by increasing levels of nitrogen under both photoperiods, however, SD photoperiod appears to moderate the response. These results indicate that BSP gene expression is dependant upon the nutritional status of the plant. [15N] analysis will also be presented.

Free access

Celina Gómez and James Robbins

The most common components of soilless container media used by the nursery industry in the United States are bark from loblolly pine ( Pinus taeda L.) and douglas fir [ Pseudotsuga menziesii (Mirb.) Franco]. Loblolly PB is widely used by growers

Open access

W. C. Morris and D. C. Milbocker

Abstract

Suppressed growth and chlorotic leaves of Japanese holly (Ilex crenata, Thunb. ‘Hetzii’) when grown in hardwood bark, were caused by the uptake of excessive amounts of available Mn in bark leachates.

Open access

J. E. Klett, J. B. Gartner, and T. D. Hughes

Abstract

Hardwood bark was used in combination with other materials as media for forsythia and juniper plants in containers with various growing procedures, bark sources, and fertility practices. Based on dry wt, the most rapid growth of forsythia was obtained in a bark and fine sand medium; whereas, the least growth was obtained in soil, peat, and perlite. However, pfitzer juniper plants under 2 different fertility regimes grew most rapidly in a bark, soil, and peat medium, slowest in a bark and torpedo #2 sand medium, and at an intermediate growth rate in soil, peat, and perlite. The standard mix (soil, peat, and perlite) was more acidic than the experimental mixes containing bark and sand. Chlorotic plants were more numerous in acidic mixes. Leaf tissue analyses from the plants grown in the peat amended bark and standard mix had higher Fe and Mn concn than plants grown in a bark-sand mix.