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Physical characteristics [initial water content, surface area, surface area: volume (SA: V) ratio, cuticle weight, epicuticular wax content, and surface morphology] were examined to determine relationships between physical properties and water-loss `rate in pepper fruits. `Keystone', `NuMex R Naky', and `Santa Fe Grande' peppers, differing in physical characteristics, were stored at 8, 14, or 20C. Water-loss rate increased linearly with storage time at each temperature and was different for each cultivar. Water-loss rate was positively correlated with initial water content at 14 and 20C, SA: V ratio at all temperatures, and cuticle thickness at 14 and 20C. Water-loss rate was negatively correlated with surface area and epicuticular wax content at all temperatures. Stomata were absent on the fruit surface, and epicuticular wax was amorphous for each cultivar.
Chemical properties of unprocessed coconut husks varied significantly between 11 sources tested. The pH was significantly different between sources and ranged from 5.9 to 6.9. The electrical conductivities were significantly different between sources and ranged from 1.2 to 2.8 mS·cm–1. The levels of Na, K, P, and Cl were significantly different between sources and ranged from 23 to 88, 126 to 236, 8 to 33, and 304 to 704 ppm, respectively. The B, Cu, Fe, Ni, S, Zn, Mn, and Mo levels were all significantly different between sources and ranged from nondetectable levels to 12.7 ppm. The NH4-N, NO3-N, Ca, and Mg levels were not significantly different between sources and ranged from 0.2 to 1.8, 0.2 to 0.9, 2.9 to 7.3, and nondetectable to 4.6 ppm, respectively. Coir dust produced by screening of waste grade coir through 13-, 6-, or 3-mm screens had significantly different bulk densities, air-filled pore space, water filled pore space and water-holding capacities compared to nonscreened waste grade coir. However, total pore space and total solids were not significantly affected by screening. Screen size did not significantly affect physical properties. Compression pressures used for formation of coir dust blocks significantly affected physical properties. Additionally, coir dust age significantly affected chemical properties.
Abstract
Cuttings of three ornamental species [Ilex × ‘Nellie R. Stevens’, (I. aquifolium × I. cornuta) Van Lennep, × Cupressocyparis leylandii Jacks & Dall. ‘Haggerston Grey’, and Lagerstroemia indica L.] were inserted in 11 media to determine the effects of physical properties of propagation media on rooting response. The physical properties of seven propagation media were altered by manipulating particle size distribution of a 1 aged pine bark : 1 composted hardwood bark (v/v) medium. Four other propagation media were used for comparison. Container capacity air space ranged from 12% to 40%, and water held after drainage in the root zone ranged from 35% to 55%. Variation in rooting response of cuttings occurred, but differences could not be attributed to the physical properties of the various media. In addition, no relationship between rooting response and engineered combinations of hardwood bark and pine bark were detected.
Abstract
Selected physical and chemical properties of pine bark, 2 sources of coal cinders, and mixtures thereof, were evaluated as container media components. Bulk density, air-filled pore space, particle-size distribution, cation exchange capacity, and soluble salt levels were quantified. Aged and freshly combusted cinders demonstrated no major physical or chemical disadvantages when used in container media. Acid and water extracts indicated that both sources of coal cinders released significant amounts of micronutrients and heavy metals. The concentrations of certain metals were sufficiently high to warrant concern over the possibility of plant nutritional disorders; whereas, other released elements resembled those of a supplemental micronutrient fertilizer.
Physical properties differed significantly among five Philippine-produced coconut (Cocos nucifera L.) coir dust sources. Bulk densities ranged from 0.04 to 0.08 g·cm–3. Air-filled pore space, water-filled pore space, and total pore space ranged from 9.5% to 12.6%, 73.0% to 80.0%, and 85.5% to 89.5% (v/v), respectively. Total solids accounted for 10.5% to 14.5% of total volume, and water-holding capacities ranged from 750% to 1100% of dry weight. Significant differences existed in particle size distribution, with the largest differences occurring for particle sizes <8.0 mm and 0.25 to 0.50 mm in diameter. Chemical properties were determined for 12 sources from the Philippines, Sri Lanka, or Indonesia. The pH and electrical conductivities ranged from 5.6 to 6.9 and 0.3 to 2.9 mS·cm–1, respectively, and were significantly different among sources. No significant differences occurred among samples with respect to Fe, Mn, Zn, B, Cu, NH4-N, and Mg concentrations. Coir dust samples contained Fe, Mn, Zn, B, and Cu at 0.01 to 0.07 mg·L–1. The levels of NH4-N and Mg were 0.1 to 0.2 and 1.0 to 7.4 mg·L–1, respectively. Significant differences occurred between sources for Ca, Na, and NO3-N, with levels (mg·L–1) ranging from 1.0 to 24.3, from 22.3 to 88.3, and from 0.4 to 7.0, respectively. The widest ranges occurred in K (19 to 948 mg·L–1) and Cl (26 to 1636 mg·L–1). Sources differed with respect to cation exchange capacities, with values ranging from 38.9 to 60.0 meq/100 g.
Chemical properties of unprocessed coconut (Cocos nucifera L.) husks varied significantly among 11 sources tested. The pH and electrical conductivities were significantly different among husk sources and ranged from 5.9 to 6.9 and 1.2 to 2.8 mS·cm−1, respectively. The
In temperate regions, the vegetable growing season is short and plastic mulches are usually left in the field for an entire year when used for double cropping. This work was conducted to study the effect of weathering on the physical, optical, and thermal properties of plastic mulches during double cropping. The design was a randomized complete block with four replications. The mulches were black, grey, infrared transmitting brown (IRT-brown), IRT-green, white, and white-on-black (co-extruded white/black). Tomato was grown the first year and cucumber the following year. The grey mulch degraded substantially during double cropping (only 40% of bed was covered the second year) and showed an increase in light transmission and a decrease in heat accumulation (degree-days). The black, whiteon-black, white, IRT-brown, and IRT green mulches showed less degradation with 93%, 91%, 85%, 75%, and 61% soil cover, respectively. However, their soil warming ability was significantly reduced. These mulches could be used for double cropping to suppress weeds and to reduce inputs associated with plastic purchase, laying, and disposal. However, they may not provide adequate soil warming early in the season for the second crop.
The effects of various substrates with or without earthworm [Eisenia fetida (Savigny, 1826] castings on growth of marigolds were evaluated. In addition, the physical and chemical properties of such substrates were determined. Castings had a greater nutrient content than the remaining substrates. The 4 pine bark: 1 sand treatment (v/v) (PBS) had higher P, K, and Zn than 7 peat moss: 3 perlite (v/v) (PP). PP had the lowest nutrient content of all substrates. Castings (C) had the highest pH followed by 1 PBS: 1 C (v/v), 2 PBS: 1C (v/v) and 3 PBS: 1C (v/v). Sunshine Mix 1 and PP had the lowest pH. EC (ER) was increased by castings, which had high ER. Castings and PP had the greatest percentage pore space. Water-holding capacity was greatest for 2 PBS: 1C (v/v) compared with Sunshine Mix 1 followed by castings. Earthworm castings increased plant growth index, stem diameter, root growth, dry weight, and flower number of marigolds compared with PP, Sunshine Mix 1, and PBS. All mixtures of castings (C) with PP, PBS, except 3 PBS: 1C (v/v), increase the growth index of plants. 1 PP: 1 C (v/v), increased flower number compared with all substrates without castings. Castings alone increased number of open flowers, but did not differ from 1 PP: 1 C or 3 PP:1 C.
substrate physical properties as it has on soil physical properties. Texture for soilless substrates can be defined as the distribution and proportions of particle sizes in a substrate resulting from grinding, processing, and decomposition of the parent
an extensive list of abiotic factors that influence root growth in containers in their review. Among them, the physical properties of growing substrate are of great importance. The air-filled porosity and the water retention capacity and availability