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Hui-qing Li, Qing-he Li, Lei Xing, Gao-jie Sun and Xiu-lian Zhao

classification of the staining intensity may be difficult ( Purcell and Young, 1963 ) and is subjective ( Nesbitt et al., 2002 ). According to Sakai (1955) , freezing injury of twigs first appears as a brown ring at the peripheral layers of the xylem and pith

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Brad B. Hawcroft and Steven E. Newman

Kenaf is an alternative fiber crop being evaluated in Mississippi. Kenaf, primarily grown in Asia, can be used in the manufacture of paper, fiber board, acoustical tiles and compost. The bark is the source of the fiber used, leaving the fiber core or pith for use as a paper additive, poultry litter, or is discarded. The objective of this study was to evaluate the potential use of kenaf fiber core as a vermiculite substitute in a sphagnum peat moss-based medium.

Plugs of Celosia argentea, Viola × wittrockiana, and Impatiens wallerana were transplanted into 10 cm pots containing 5 different sphagnum peat moss-based media modified with the milled fiber core (pith) of kenaf (Hibiscus cannabinus) and/or vermiculite. The media were as follows: 5 peat: 0 kenaf : 5 vermiculite (v/v/v); 5 peat : 1 kenaf : 4 vermiculite (v/v/v); 5 peat : 2 kenaf : 3 vermiculite (v/v/v); 5 peat : 3 kenaf : 2 vermiculite (v/v/v); 5 peat : 4 kenaf : 1 vermiculite (v/v/v); and 5 peat : 5 kenaf: 0 vermiculite (v/v/v). Water holding capacity, pore space, pH and media shrinkage were monitored throughout the study along with plant growth and plant quality.

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Reeser C. Manley and Rita L. Hummel

Winter survival of cabbage seed crops is limited by the freezing resistance of the lower stem pith tissue. Both tolerance of extracellular freezing and avoidance of lethal temperatures are components of stem pith tissue freezing resistance. The avoidance mechanism involves the formation of ice within the pith tissue at relatively warm temperatures (little undercooling) and the subsequent release of heat of fusion, followed by significant slowing of the freezing rate so that stem temperatures are mitigated against ambient temperatures for several hours.

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Alan W. Meerow

Coir is the name given to the fibrous material that constitutes the thick mesocarp of the coconut fruit (Cocos nucifera L.). The long fibers of coir are extracted from the coconut husk and utilized in the manufacture of various products. The short fibers and dust (“pith”) left behind have accumulated as a waste product. Coir pith is light to dark brown in color and consists primarily of particles in the size range 0.2-2.0 mm (75-90%). In composition, it is 65-70% lignin and 20-30% cellulose. To date, few replicated tests have assessed the performance of coir pith as a plant growth medium. From April, 1993 to April, 1994, four ornamental crops (pentas, ixora, anthurium and majesty palm) were grown in container media that differed only in the peat fraction (40%), either sphagnum, Florida (sedge) peat, or coir pith. On the basis of plant growth parameters, coir pith was superior to sedge peat as a medium component (though only marginally for the anthurium) and at least equal to sphagnum peat. In addition to physical qualities equal to or better than sphagnum peat, coir decomposes more slowly than either sedge or sphagnum peat, withstands compression better and is easier to wet than peat. There are also no ecological drawbacks to the use of coir -- a waste product -- relative to the harvest of peat from wetland ecosystems.

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Andrea Luvisi, Alessandra Panattoni, Roberto Bandinelli, Enrico Rinaldelli, Mario Pagano, Barbara Gini, Giorgio Manzoni and Enrico Triolo

one (5 mm higher). Direct drilling of the pith with a 2.5-mm drill bit was then performed to a depth of 40 mm for R1 and R2 treatments, followed by microchip insertion in R1-treated plants ( Fig. 1 ), locating the TAG below the higher bud. The cut was

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Mitchell W. Goyne and Michael A. Arnold

Four underutilized small trees, Chilopsis linearis, Rhus lanceolata, Acacia wrightii, ×Chitalpa tashkentensis, and a commercial control Fraxinus velutina, were grown outdoors in 15-L containers. Four media combinations, 3 pine bark: 1 sand, 3 pine bark: 1 coconut coir pith, 3 kenaf stalk core: 1 sphagnum peat, and 3 kenaf stalk core: 1 coconut coir pith (v/v), were amended with Sierrablen 18N–2.6P–10K at three rates, 3.6, 7.1, and 10.7 kg·m-3. Fraxinus velutina and C. linearis seedlings were transplanted to the field to evaluate initial landscape establishment. Growth was typically reduced, in both the field and container, when kenaf media was used during production. EC was greatest early and with higher fertility rates. Leachate pH decreased over time, and was lower at high fertility rates. Soil particle size >6.0 mm decreased substantially in kenaf media over time. Water holding capacity increased, while air space and total root volume decreased in kenaf media. Physical characteristics and growth responses were similar with coconut coir and peat moss.

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Mitchell W. Goyne and Michael A. Arnold

Growth responses during nursery production in 2.2- and 11.4-liter plastic containers to conventional and alternative media of four species of small trees of limited availability for potential use in urban sites in the southwest United States (Acacia wrightii, Chilopsis linearis, × Chitalpa tashkentensis, and Rhus lanceolata) were compared to that of a commercially available small tree (Fraxinus velutina). Four media combinations, at 3:1 (v/v) of bark: sand (conventional), bark: coconut coir pith, kenaf stalk core: peatmoss, and kenaf: coir, with three fertilizer concentrations (3.6, 7.2, and 10.7 kg·m–3 of 18N–2.6P–10K Osmocote) were tested with each species. All species exhibited commercially acceptable growth (80 to 167 cm mean heights in 11.4-liter containers in 240 days) with near 100% survival in most media and fertilizer combinations with the following exceptions: shoot extension of Rhus lanceolata was reduced by 20 to 30 cm and survival by 20% to 50% in kenaf media with high fertility rates; and Acacia wrightii had acceptable shoot extension but exhibited poor trunk diameter growth across media relative to the other species. Slightreductions in growth of some species were noted with kenaf media and slight increases with coconut coir, but differences were not likely of commercial significance. Kenaf media was significantly lighter (20% to 80%) than bark media, but had elevated initial electrical conductivity (EC) and shrank to 60% to 70% of its initial volume after 240 days. Kenaf: peatmoss media had a slightly lower mean pH (6.34) compared to the other media (pH 6.41–6.49).

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John McCallum, Susan Thomson, Meeghan Pither-Joyce, Fernand Kenel, Andrew Clarke and Michael J. Havey

-pollinated onions from Argentina and Brazil Allium Improvement Nwsl. 9 1 4 Martin, W. McCallum, J. Shigyo, M. Jakse, J. Kuhl, J. Yamane, N. Pither-Joyce, M. Gokce, A. Sink, K

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Alan W. Meerow

Growth of Pentas lanecolata (Forssk.) Deflers `Starburst Pink' and Ixora coccinea L. `Maui' was compared in container media using sphagnum peat, sedge peat, or coir dust as their peat components. Growth index and top and root dry weights of both crops were significantly better in coir-based medium than sedge peat-based medium. Pentas grew equally well in coir- and sphagnum peat-based medium. Growth index and top dry weight of Ixora were significantly lower in the coir-based than the sphagnum peat-based medium, although root dry weights were equal. This difference was not apparent and may have been caused by N drawdown in the coir-based mix. The sedge peat-based medium had the highest air porosity and the lowest water-holding capacity of the three media at the initiation of the trials, but at the termination of the study, it showed a reversal of these characteristics. The coir-based medium showed the least change in these attributes over time. Coir dust seems to be an acceptable substitute for sphagnum or sedge peat in soilless container media, although nutritional regimes may need to be adjusted on a crop-by-crop basis.

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S.P. Vander Kloet and J. Pither

Periodic prescribed burns of lowbush blueberry barrens promote high yield, aid in weed control, and reduce fungal and insect damage. Whether such prescribed fires should be set in the autumn or the spring has been a matter of some dispute. Previous research on Vaccinium angustifolium Aiton suggested some advantages to autumnal burning, but few data have been collected on V. myrtilloides Michaux. To evaluate whether time of burning affected plant qualities most favorable for mechanical harvesting, such as stem length and lateral branching, a series of experiments was conducted on V. myrtilloides. Differences in stem length, numbers of lateral branches, and buds per stem were nonsignificant among plants burned in fall vs. those burned in spring. In three of four experiments, however, fall burns resulted in the growth of fewer lateral branches. Furthermore, among the four experiments, growth responses were more uniform following fall than following spring burns. We therefore suggest that, where possible, fall burns should be prescribed for blueberry plants that will be mechanically harvested.