Baked ceramic aggregates (fritted clay, arcillite) have been used for plant research both on the ground and in microgravity. Optimal control of water and air within the root zone in any gravity environment depends on physical and hydraulic properties of the aggregate, which were evaluated for 0.25-1-mm and 1-2-mm particle size distributions. The maximum bulk densities obtained by any packing technique were 0.68 and 0.64 g·cm-3 for 0.25-1-mm and 1-2-mm particles, respectively. Wettable porosity obtained by infiltration with water was ≈65%, substantially lower than total porosity of ≈74%. Aggregate of both particle sizes exhibited a bimodal pore size distribution consisting of inter-aggregate macropores and intra-aggregate micropores, with the transition from macro- to microporosity beginning at volumetric water content of ≈36% to 39%. For inter-aggregate water contents that support optimal plant growth there is 45% change in water content that occurs over a relatively small matric suction range of 0-20 cm H2O for 0.25-1-mm and 0 to -10 cm H2O for 1-2-mm aggregate. Hysteresis is substantial between draining and wetting aggregate, which results in as much as a ≈10% to 20% difference in volumetric water content for a given matric potential. Hydraulic conductivity was approximately an order of magnitude higher for 1-2-mm than for 0.25-1-mm aggregate until significant drainage of the inter-aggregate pore space occurred. The large change in water content for a relatively small change in matric potential suggests that significant differences in water retention may be observed in microgravity as compared to earth.
Conservation tillage using residue from a cover crop grown before potato (Solanum tuberosum L.) production has been infrequently and inconclusively studied. The objectives of this study were to 1) conduct a field study to evaluate soil physical properties, and potato growth and yield, in conventional-tillage (CT), no-tillage (NT), and subsurface-tillage (SST) systems and 2) conduct a greenhouse study to evaluate the effect of soil bulk density (ρb) on potato growth and yield. Potatoes (`Atlantic') were planted into residue of sorghum-sudangrass [Sorghum bicolor (L.) Moench × S. sudanense (Piper) Staph] at two sites in eastern North Carolina—Plymouth into Portsmouth fine sandy loam and Lewiston into Norfolk sandy loam. Potatoes in the NT and SST system emerged more slowly than potatoesplanted conventionally. There were no differences in plant population or size by 8 weeks after planting at Plymouth, but plant population and size were less in NT and SST systems at Lewiston. Reducing tillage also affected soil compaction, increased soil moisture early in the season at both sites, and increased ρb at Lewiston. Yield of U.S. No. 1 potatoes planted in NT and SST systems were comparable to potatoes planted in a CT system at Plymouth, but were less than potatoes planted in a CT system at Lewiston. There were no differences in yield between potatoes planted with NT and SST. In the greenhouse study, ρb did not affect leaf area or tuber yield or tuber grade. Specific sites and soils may allow for comparable potato production with no or SST, but further research, conducted on different soil types would promote further understanding of the impacts of reducing tillage in potato production.
properties as required by the specific crop and growing conditions ( Bunt, 1988 ). An important physical property of substrates is air-filled pore space. Air-filled pores allow for drainage and gas exchange between the root environment and the outside
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
The objective of this study was to evaluate the potential use of container substrates composed of whole pine trees. Three species [loblolly pine (Pinus taeda), slash pine (Pinus elliottii) and longleaf pine (Pinus palustris)] of 8–10 year old pine trees were harvested at ground level and the entire tree was chipped with a tree chipper. The chips from each tree species were then further processed with a hammer mill to pass a ½-inch screen. On 29 June 2005 these three substrates along with 100% pinebark were mixed with the addition per cubic yard of 9.49 kg·m–3 Polyon 18–6–12 (18N–2.6P–10K), 2.97 kg·m–3 dolomitic lime and 0.89 kg·m–3 Micromax. One gallon (3.8 L) containers were then filled and placed into full sun under overhead irrigation. Into these containers were planted 72 cell plugs of Catharanthus roseus`Little Blanche'. Data collected were pre-plant chemical and physical properties of substrates, as well as plant growth index (GI), plant top dry weight, root ratings, and plant tissue (leaves) nutrient analysis at 60 days after planting (DAP). The test was repeated on 27 Aug. 2005 with C. roseus Raspberry Red Cooler. Top dry weights were on average 15% greater for the 100% pinebark substrate over all others at 60 DAP. However there were non differences in plant GI for any substrate at 60 DAP. There were no differences in plant tissue macro nutrient content for any substrate. Tissue micronutrient content was similar and within ranges reported by Mills and Jones (1996, Plant Analysis Handbook II) with the exception of Manganese. Manganese was highest for slash and loblolly pine and well over reported ranges. There were no differences in root ratings. There were no differences in substrate physical properties between the three whole tree substrates. However the 100% pinebark substrate had on average 50% less air space and 25% greater water holding capacity than the other substrates. Physical properties of all substrates were within recommended ranges. Based on the results of this study substrates composed of whole pine trees have potential as an alternative sustainable source for a substrate used in producing short term nursery crops.
Physical and chemical properties of Red Roomy grapes in response to spraying cycocel and some micronutrients were investigated through two consecutive seasons. One spray 15 days before first bloom, 30 days after berry .set, or all of the three previous dates together and/or using Mn, Zn, Cu, and Fe in combination at 0.0% or 0.3% in sulphate form were applied. Three sprays of cycocel at 1000 ppm in combined with the four micronutrients together at 0.3% exerted a lower percentages shot and cracked berries and total acidity and a greater total soluble and total sugars percentages. The adverse effect of cycocel can be diminished by spraying the micronutrients with it together at 0.3%. The most pronounced effect on berries quality was obtained as a result of spraying Red Roomy vines with cycocel at 1000 ppm plus the application of Mn, Zn, Cu, and Fe at 0.3% three times.
Hydrophilic polymers or hydrogels have shown potential to increase water retention of media and to reduce irrigation frequency. This property would be particularly useful in the production of fast growing species in which large amounts of water are needed. This study evaluated the effect of two acrylic-based hydrogels on water desorption curve and hydraulic conductivity of substrates and on plant growth. The duration of their effects was also investigated. Rooted cuttings of Surfinia (Petunia ×hybrida `Brilliant Pink') were transplanted into 30-cm pots containing one of three different substrates amended with one of two types of hydrogels, a commercial acrylic polymer, and a commercial acrylic-acrylamide copolymer, and grown for 9 weeks under well watered conditions and then imposed with a drought. Results indicated that both polymer types gave similar results. The substrates' physical properties (air-filled porosity, available water) at potting time were significantly affected by hydrogel addition, but differences vanished within 9 weeks of growth. Hydrogels had no significant effect on the point at which plant wilted and on the substrate's unsaturated hydraulic conductivity. Shoot dry weight was affected by substrate and hydrogel and was positively correlated to water content between container capacity and -10 kPa of water potential, or between container capacity and the soil water potential at plant turgor loss.
Energized water production: Underground water, which was not con-taminated with heavy metal ions, chemicals, and much nitrate, etc. => 1) filtering through reversed osmosis pressure filter, 2) nano-sized mineral system with specific stone powder, 3) far red light expositing system, 4) magnetic field treatment, 5) oxygen supply system => energized water (EW). Physical and chemical properties: EW showed higher pH level, electrical conductivity (EC), energy levels by Killian camera and oxygen concentration; however, lower ORP, cluster size as much as 79 Hz by NMR in comparison to underground water, as control. Bioassay of sprouting vegetable plants: In barley germination test, EW showed higher germination rate, strong top/root growth, especially outstanding differentiation of roots in comparison to control. After 2 weeks, the control barley seedlings showed significant symptoms of senescence in root tissue. Also, bean sprouts greatly increased growth in epicotyls and hypocotyls, and development under EW conditions. The roots of control plants showed discolored and mal flavors and gradually decayed in room temperature. With EW supply, vegetable seeds and sprouting plants showed better growth and development of top and root parts. In conclusion, EW influenced the plants to have higher biodynamic potentials for seed germination and growth and development of new plant tissues.
, rice hulls, various composts, and vermiculite to provide suitable physical and chemical properties as required by the specific crop and growing conditions ( Bunt, 1988 ; Raviv and Lieth, 2008 ). Among the most commonly evaluated and reported physical
properties. To determine fruit physical properties, four fruits were randomly selected from each tree replication, and fruit weight was measured using an electronic balance. Fruit diameter and length, fruit calyx diameter (the widest part of the neck), and