Polyethylene Tent Research Articles

Vegetative propagation of Juniperus osteosperma (Utah Juniper) by cuttings

Utah juniper ( Juniperus osteosperma (Torr.) Little [Cupressaceae]) was vegetatively propagated using tip cuttings from juvenile plants. Rooting was most successful (69%) when cuttings were treated with indole butyric acid (IBA) in talc (0.8% ai), struck in 2:1 perlite:peat (v:v) rooting substrate, provided bottom heat, and kept on a mist bench covered by a white polyethylene tent in a greenhouse environment with supplemental lighting. Utah juniper is highly drought tolerant, and superior accessions may have potential for increased use in water-conserving landscapes. The ability to propagate it by vegetative means should facilitate the selection and development of superior plants for use in the landscape industry.

Transfer factors of Polonium from soil to parsley and mint

Transfer factors of 210Po from soil to parsley and mint have been determined. Artificial polonium isotope ( 208Po) was used as a tracer to determine transfer factor of Po from soil to plant in pot experiments. Two plant growing systems were used for this study namely, an outdoor system and a sheltered system by a polyethylene tent. 208Po and 210Po were determined in soil and different parts of the studied plants (stem and leaf), using alpha spectroscopy. The results have shown that there was a clear uptake of 208Po by roots to leaves and stems of both plants. Higher values of transfer factors using the 210Po activity concentrations than the 208Po activity concentration were observed. Transfer factors of 210Po from soil to parsley varied between 20 × 10 −2 and 50 × 10 −2 and 22 × 10 −3 and 67 × 10 −3 in mint, while 208Po transfer factors varied between 4 × 10 −2 and 12 × 10 −2 for parsley and 10 × 10 −2 and 22 × 10 −2 in mint. Transfer factors of Po were higher in those plants grown in the sheltered system than in the open system; about 75% of Po was transferred from atmosphere to parsley parts using the two systems. Ratios of transferred Po from soil to mint stem and leaf in the sheltered system were higher by 2 times from those in the open system.

Avian Influenza Outbreak Management: Action at Time of Confirmation, Depopulation and Disposal Methods; the ‘Belgian Experience’ during the H7N7 Highly Pathogenic Avian Influenza Epidemic in 2003

Eradication of H5 and H7 influenza in a positive flock will include mass depopulation of birds, containment and inactivation of the virus in the carcasses and litter, and decontamination of the facility. A quick response is desired in the event of a disease outbreak. Ideally, birds should be depopulated within 24 h after detecting the virus. Mass depopulation of birds must be performed in a humane manner while minimizing human health and biosecurity risks. In the framework of the European legislation, a number of methods are authorized for the killing of poultry for processing prior to marketing. However, during emergencies such as a disease outbreak, there are fewer options. The current most commonly used procedures for large-scale emergency depopulation of birds consist of exposing poultry to CO or CO(2) gas. Both gasses have been used in Belgium during the H7N7 crisis in 2003. The gassing procedures include whole house gassing, portable panel enclosures, cage cabinets, containers and polyethylene tent method. Whole house gassing requires sealing the house to prevent gas leakage and, using specialized equipment, introducing large volumes of gas evenly over the birds. All procedures are very labour intensive, create a biosecurity risk and require a large number of personnel. There are considerable region-to-region differences in emergency depopulation techniques and disposal of carcasses and infected material. Because of the differences in bird type and species, management, housing and stocking density, it is difficult to propose a depopulation technique that will be suitable for all circumstances. Safety of the human operators is an increasing concern with all H5 and H7 strains and in particular with the highly pathogenic H5N1 strain. Researchers and commercial poultry companies in the United States recently established that non-toxic water-based foam with a certain bubble size presents a practicable, effective and humane method for mass depopulation. Foam of the right bubble size creates an occlusion in the trachea of birds, causing a rapid onset of hypoxia. The foam that blankets the broiler house induces physical hypoxia - the same cause of death as the approved method using carbon dioxide gas (CO(2)). The article illustrates the different culling and disposal methods with a focus on the methods used during the 2003 H7N7 crisis in Belgium.

Foam-Based Mass Emergency Depopulation of Floor-Reared Meat-Type Poultry Operations

Current control strategies for avian influenza and other highly contagious poultry diseases often include quarantine, depopulation, and disposal of infected birds. For biosecurity reasons, on-farm depopulation and disposal methods are preferred. The options for mass depopulation are limited, as reported by the "2000 Report of the AVMA Panel on Euthanasia." Current depopulation techniques may have excessive labor requirements, are not appropriate for all house types, and may not be suitable for large-scale emergency implementation. A procedure has been developed that uses foam to rapidly form a blanket over the birds. The procedure requires relatively few people, can be performed in a variety of house types, and is compatible with in-house composting. Results from 2 experiments using foam for depopulation are presented in this paper. These studies have shown that foams are comparable to the CO(2) polyethylene tent procedure in time to death in small groups and that the foam is faster as group size increases. Adding CO(2) to the foam does not enhance its efficacy. Based on corticosterone levels, the study also showed that the foams are no more stressful than the CO(2) depopulation method. Necropsy and histological examination of birds indicated that blood was present to some degree in the trachea, syrinx, and bronchial tree in broilers subjected to foam with CO(2), foam without CO(2), and CO(2) polyethylene tent methods of depopulation. Foam caused a rapid onset of airway occlusion. In both foam- and CO(2)-euthanized broilers, lesions are consistent with anoxia or hypoxia. This suggests that foam acts by physically induced hypoxia, whereas CO(2) causes chemically induced hypoxia.

EVALUATION OF FOAM-BASED MASS DEPOPULATION METHODOLOGY FOR FLOOR-REARED MEAT-TYPE POULTRY OPERATIONS

Current methods of control for quick spreading, highly contagious poultry diseases, such as avian influenza (AI)or Exotic Newcastle, require large numbers of poultry to be rapidly killed to prevent further spread. On-farm depopulation,rather than conventional slaughter at a processing plant, is preferred to avoid the spread of potentially zoonotic agents. Ittherefore makes sense to depopulate or euthanize the birds as soon as possible and on site. In these circumstances, the mostappropriate technique that minimizes human and animal health concerns should be used. The options for mass depopulationare limited, as reported by the 2000 Report of the AVMA Panel on Euthanasia (AVMA, 2001). While these methods are humaneand fairly expedient, these procedures are labor intensive and require a significant number of people be involved in theprocess. This project explores the use of a carbon dioxide (CO2) enriched fire fighting foam system to perform mass emergencydepopulation of poultry. The method utilizes a blanket of high expansion foam enriched with carbon dioxide. In fourexperimental trials, the method has been shown to provide effective depopulation. The foam with varying concentrations ofcarbon dioxide was directly compared to a currently industry accepted CO2-polyethylene tent method, which uses overlappinglayers of polyethylene to cover birds and then gassing with carbon dioxide. The foam and polyethylene tent methods resultedin death in less than 3 min (CO2-polyethylene 2:08 min, foam with CO2 2:09 min, and foam without CO2 2:54 min).Preliminary results indicate that the fire fighting foam is as effective or more effective than conventional CO2-polyethylenetent method.

Low Irradiance During Rooting Improves Propagation of Oak and Maple Taxa

Abstract Rooting trials were conducted to determine if the duration of exposure to low levels of solar irradiance during root initiation influenced rooting and survival of semihardwood cuttings of six tree species. Cuttings of oak (Quercus imbricaria, Q. nigra, Q. palustris, Q. rubra) and maple (Acer rubrum ‘Bowhall’, and A. truncatum) were treated with IBA and placed in a fog-humidified polyethylene tent rooting chamber for 119 or 117 days (A. rubrum and Q. nigra) under either 82% (control) or 93% (low irradiance) shading of ambient outdoor solar radiation. Cuttings were exposed to either 0, 10, 20, 40, or 119 days of 7% irradiance followed by placement under control conditions (18% irradiance) for the remainder of the treatment. Percentage rooting, the number of roots per cutting, and the number of days to root were significantly influenced by exposure to 7% irradiance during rooting, but responses were dependent on taxa. For most taxa, the highest rooting percentages required at least 10 days of exposure to 7% irradiance. Overwinter survival of rooted cuttings averaged 58.8% and was not affected by treatment. Results of this study demonstrate that low irradiance in the rooting environment can increase the rooting of cuttings of oak and maple taxa.

260 Micropropagation of Baptisia bracteata Mnhl. via Direct Regeneration

Native plants are often ignored in horticulture because they may lack major ornamental traits and many of them are difficult to propagate. Creamy indigo (Baptisia bracteata Mnhl.) is a North American legume with considerable potential as a container-grown or ornamental plant for managed landscapes. Nodal explants from aseptically germinated seedlings were evaluated for axilary shoot and leaf development. The explants were cultured on Murashige and Skoog medium (MS) containing adenine sulfate at 80 mg•L-1, 30% sucrose, and different levels of N-6-benzyladenine (BA) (0.5,1.0,2.0 mg•L-1) supplemented with indole-3-acetic acid (IAA) (0.05, 0.1 or 0.5 mg•L-1) or with IAA omitted. Shoot regeneration occurred within 2 to 3 weeks. The best medium for shoot regeneration was MS supplemented with BA at 1.0 mg and IAA at 0.1 mg•L-1. Shoots were transferred onto rooting medium consisting of Ω MS supplemented with 1.0 mg alpha-naphthaleneacetic acid (NAA) and 1.0 mg indole-3-butyric acid (IBA)/L and 20% sucrose. Rooting took place within 3 to 5 weeks. Plantlets were then planted in soil mix, placed under a polyethylene tent for 2 weeks, and transferred into the greenhouse for further growth.

Effect of Shade Levels and IBA During the Rooting of Eight Tree Taxa

Abstract Softwood shoot cuttings of Acer griseum, A. rubrum ‘Bowhall’, A. rubrum ‘Franksred’ Red Sunset™, A. saccharum ‘Legacy’, Cornus kousa, Quercus alba, Q. ellipsoidalis, and Q. palustris were subjected to hormone treatments (IBA and control) and placed in a fog-humidified polyethylene tent rooting chamber under one of three levels of shade (83% or control, 91%, and 97% of ambient sun). Percentage rooting, the number of roots per cutting, and the number of days to root were significantly influenced by shade levels and hormone treatment, but responses were dependent on species or cultivar. For most taxa, percentage rooting was greatest at 91% or 97% shade. Only for A. griseum was the control shading treatment best for rooting. Generally, under the greater shade levels, the IBA treated cuttings rooted more often, had more roots, and rooted faster than cuttings without IBA. However, in some cases, the hormone treatment did not provide a clear advantage. Results of this study demonstrate that high shade levels in the rooting environment can increase the rooting performance of cuttings of a number of woody plant taxa.

The effects of in vitro hardening using triazoles on growth and acclimatization of banana

Banana shoots micropropagated from floral apices were grown in Stage III culture media with 0, 1, 2 or 4 mg l −1 of triazoles (triadimefon or uniconazole) for 1 month. The resulting plantlets were then transferred to a peat moss and sand (1:1, v/v) potting mix and post-transplant performance was evaluated. In vitro triadimefon treatment (2 mg l −1) acted as a conditioning agent and obviated the need for hardening or weaning the plantlets under a polyethylene tent. Triadimefon-treated plants were turgid and healthy compared with control plants. Control plants which were not acclimatized wilted, and the leaves dried up, whereas plants treated with triadimefon, particularly with 2 mg l −1, remained turgid. All plants treated with uniconazole dried up upon transplanting.

Transfer of 210Pb and 210Po to plants via root system and above-ground interception

The aim of this study was to investigate the effect of atmospheric deposition of 210Pb and 210Po on their transfer to plants used as food (potatoes, vegetables, cereals) and as fodder (grass, alfalfa). Two types of soil on an open field and on a field sheltered by a polyethylene tent were used. 210Pb and 210Po were determined in the total deposition, soils and plants. In the above-ground parts of the plants grown on the open field the activity concentrations of 210Pb and 210Po were higher than those for the plants grown in the tent, whereas in the roots they were nearly the same. Different concentrations of the radionuclides in the above-ground parts, despite the similar concentrations in roots, suggest that the transfer of the radionuclides via the root system is rather negligible. The data obtained indicate that atmospheric deposition is the main source of 210Pb and 210Po in the above-ground parts of the plants. It is suggested that the incorporation of the radionuclides occurs mainly from the wet deposition.

EFFECTS OF STOCK PLANT ETIOLATION ON THE ROOTING OF SASKATOON BERRY (Amelanchier alnifolia Nutt.) CUTTINGS

The etiolation of field-grown, rejuvenated saskatoon berry (Amelanchier alnifolia Nutt.) bushes in 1984 and 1985 proved to be a beneficial aid-to-rooting of softwood cuttings under intermittent mist. The cuttings had to be regreened for a short period of time (6 d) before they were exposed to direct sun in the outdoor intermittent mist propagation bed covered with a clear polyethylene tent. The tedious and time-consuming taping of shoot bases during the regreening period to continue the etiolation process at the base of the cutting proved to be unnecessary with the cultivar Smoky, but gave increased rooting percentage and root mass with the cultivar Pembina on regreened etiolated cuttings in combination with a concentrated auxin. The regreened etiolated treatments produced 95% rooting without auxin with both cultivars. The beneficial effect from the use of a concentrated auxin as a quick dip was more evident on the nonetiolated material, but still increased root mass on the etiolated plant material.Key words: Saskatoon berry, intermittent mist propagation, auxin, softwood cuttings, Amelanchier alnifolia

Comparative rooting of eighty-one species of leafy cuttings in open and polyethylene-enclosed mist systems

SummaryThe rooting of leafy cuttings of 81 species and cultivars was compared in two propagation systems: conventional intermittent mist (M) and intermittent mist inside a raised polyethylene tent (MP). Both systems were shaded to reduce the light level to around 1.5 MJ m-2 d-1. The rooting response of conifers and broad-leaved species differed, the latter rooting equally well in either system. Species susceptible to water stress (e.g. those with thin, immature foliage lacking full cuticular protection) rooted better in MP. Measurements of water and solute potentials of leaves, made before rooting began, showed that the MP system minimized water stress in most species. However, except in the particularly susceptible cuttings mentioned above, the shading employed ensured that water stress was seldom critical in either system. Solute potentials, were less negative in MP than in M for most species, especially conifers, causing lower turgor in comparatively unstressed cuttings. The decline in solute concentra...

Environmental factors affecting water loss from leafy cuttings in different propagation systems

SummaryA detailed examination is presented of the microclimates of three propagation systems (mist, polyethylene tent and contact polyethylene). The relationship between the water vapour pressure difference between the leaf and the surrounding air (Δν) and incident irradiance (I) was established for each system: in all three it was approximately linear. Values of Δ ν at the highest measured I (300 W m-2) were c. 1.0 kPa under mist, 2.5 kPa under contact polyethylene and 4.0 kPa under polyethylene tents. The components of Δν (leaf vapour pressure and air vapour pressure) are analysed.

Experimental control of water status in an apple orchard

SummaryA system of under-tree polyethylene tent covers was used in conjunction with irrigation treatments to induce a range of soil moisture regimes in a Bramley apple orchard. The treatments included one of covers plus added irrigation to determine any effects of the covers independent of the effects on soil water status. The covers successfully reduced precipitation reaching the root zone, so that quite large differences in soil water content between treatments were observed. There was, however, strong evidence that stomatal closure in the drier treatments minimized treatment differences in leaf water potential. This effect was more marked in younger trees. In the first year this stomatal closure was so effective that ‘over-control’ occurred such that the droughted trees had higher leaf water potentials than the irrigated trees at the end of the season. Generally, however, leaf water potentials were between 0.1 and 0.2 MPa (1 and 2 bar) lower in the droughted than in the irrigated trees. Comparisons of soil temperatures under drought covers and either a cover plus irrigation treatment or natural rainfall indicated that observed differences were related to altered soil moisture regime rather than any direct effect of covers on air flow or radiation climate.

PROPAGATION OF OTTAWA APPLE ROOTSTOCKS BY SOFTWOOD CUTTINGS

The difficulty in rooting Ottawa 3 apple (Malus sp. Mill.) rootstock by softwood cuttings under intermittent mist at other locations was not experienced at Saskatoon, Saskatchewan. With the exception of Ottawa 7, which would seem to be slower rooting than the rest of this rootstock series, namely, Ottawa 3, 5, 8, 11 and 12, high levels of rootability were obtained with 12.7-cm (5-inch) softwood cuttings under three types of intermittent mist propagation outdoors. The polyethylene tent over the intermittent mist bed was generally superior to the open intermittent bed with bottom heat and it, in turn, superior to the open intermittent mist bed without bottom heat. The use of hormone applications tended to speed up rooting and increased the yield of the root mass in the 7-wk period, but only in a few instances were there statistically significant differences.