Grevillea ( Offord et al., 1998 ). The feasibility of using pine bark mixtures in substrate formulation was shown in Pinus and Cupressus by Guerrero et al. (2002) and Hernández-Apaolaza et al. (2005) . The effect of adding composted waste to a peat
A greenhouse experiment was conducted to determine the relationship between milled pine bark amended soils (0, 25, and 50% pine bark mixed with soil, by volume), and applied compaction rates (0, 20, 40, 60, and 80 psi) on vegetative growth, root development, and cold tolerance of ‘Tifgreen’ bermudagrass. One-half of the unamended soil and of the pine bark amended soils was also overlain with a 3-inch milled pine bark layer (cushion) in an attempt to absorb compaction forces.
Soil compaction significantly reduced top and root development of the bermudagrass. Forty to 60 psi represented the point at which soil compaction became a severely limiting factor in turf growth. A 3-inch surface layer of pine bark offset the value of incorporating pine bark as a soil amendment. Amending the soil with pine bark (up to 50% by volume) increased vegetative growth and root development of turf and delayed the onset of adverse conditions caused by soil compaction.
‘Tifgreen’ bermudagrass recovered best from low temperature (-9.4°C for 5 hr) exposure when grown in soils receiving compaction pressures less than 40 psi and which were amended with 50% milled pine bark, 25% milled pine bark, or were unamended.
irrigated substrate without plants to preclude the difficulties noted earlier, with repeat samples collected over time to allow a more thorough assessment. Materials and Methods Substrate. The substrate used in the study was a 25 pine bark (6
Plant height of potted Bouvardia humboldtii Hort. was controlled effectively by foliar or drench applications of paclobutrazol. Three foliar applications of 250 mg·liter−1 paclobutrazol or a drench of 2 mg/100-mm-diameter pot reduced plant height by≈30% and increased the total number of flowers per plant by ≈35%. Overall, paclobutrazol significantly reduced total plant dry weight, and sprays were more inhibitory than drenches. Paclobutrazol altered the shoot : root ratio in favor of the shoot. Foliar sprays of daminozide (5000 mg·liter−1) or chlormequat (2000 mg·liter−1) were ineffective in controlling growth or flowering. It is concluded that paclobutrazol application may be a useful technique in the commercial production of Bouvardia as a flowering pot plant. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-l-ethanol [paclobutrazol (ICI-PP333)].
Many research studies have evaluated potential organic and mineral container substrate components for use in commercial potting substrates. Most studies report results of plant growth over a single production season and only a few include physical properties of the substrates tested. Furthermore, substrates containing predominantly organic components decompose during crop production cycles producing changes in air and water ratios. In the commercial nursery industry, crops frequently remain in containers for longer periods than one growing season (18 to 24 months). Changes in air and water retention characteristics over extended periods can have significant effect on the health and vigor of crops held in containers for 1 year or more. Decomposition of organic components can create an overabundance of small particles that hold excessive amounts of water, thus creating limited air porosity. Mineral aggregates such as perlite, pumice, coarse sand, and calcined clays do not decompose, or breakdown slowly, when used in potting substrates. Blending aggregates with organic components can decrease changes in physical properties over time by dilution of organic components and preserving large pore spaces, thus helping to maintain structural integrity. Research is needed to evaluate changes in container substrates from initial physical properties to changes in air and water characteristics after a production cycle.
successful: 1) planting in pine bark beds ≈6 to 8 inches deep with overhead irrigation, 2) planting in high organic matter (greater than 3%) spodic-type or allied sand soil series, and 3) planting in sand or loamy sand soils and amending the soil with pine
of composted pine bark (35% to 45%) and coconut coir pith (20% to 30%), whereas the primary components of both SB300 Universal Professional Growing Mix and Sunshine LC1 Mix are composted pine bark (50%) and Canadian sphagnum peatmoss (75
the landscape. Because landscape soils differ greatly in physical and chemical properties from the substrates used in container production, the nutritional requirements are therefore also quite different. In the southeastern United States, pine bark is
d, a high relative humidity (80% to 90%) was maintained by keeping the trays covered with plastic, translucent lids. The relative humidity was then decreased to 50% to 60%. Three different substrates were used: 1) pumice; 2) pine bark, oak charcoal
base of selected trees to form a 2.3-m diameter circle. On 29 Mar., composted pine bark mulch (screened to ≈5.0 cm) was placed around trees with steel edging to a depth of 10.2 cm. Pine bark mulch was maintained at this depth throughout the experiment