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  • Author or Editor: Jacques-André Rioux x
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The main objective of this research was to determine the propagation potential of Juniperus scopulorum `Wichita Blue' through grafted cuttings while using Juniperus chinensis `Hetzii' and Juniperus Sabina `Blue Danube' as a rootstock. The experiment took place in a glass greenhouse, the propagation material was either placed under a polyethylene film or intermittent mist. In each of these growth conditions the graft union was either wax coated or buried in a humid substrate. Grafting method was a side veneer graft. Each treatment was repeated three times and the experimental unit was made up of ten specimens.

Best results were obtained from the experimental trial covering the period of february to may (12 weeks). During this trial period we observed a similar rate of successful graft union whether grafted cuttings or conventional graft was used with J. S. `Blue Danube', while grafted cuttings was more successful with J. c. 'Hetzii'. Grafted cutting obtained the best results with J. S. `Blue Danube' when graft union was buried in perlite and placed under an intermittent mist. Rooting quality of rootstock cuttings was slightly inferieur to conventional cuttings for J. S. `Blue Danube' this difference was more prononced in the case of J. c. `Hetzii'

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The richness of the organic residues in certain fertilizing elements justifies their valorization in horticulture. However, their contents in pathogenic and toxic elements can restrict their use. In this context, this study was conducted in order to evaluate the effect of three organic residues on the environmental medium and the risks of water contamination by the release of heavy metals. Physocarpus opulifolius `Nanus' was transplanted into four substrates. The control substrate contained 4 peatmoss: 5 composted conifer bark: 1 fine crushed gravel (by volume). The three other substrates (25% of peatmoss was substituted by organic residue) contained 10% of fresh bio-filters (FBF), 10% of composted sewage sludges (CSS), or 10% of de-inking sludges (CDS). The pots (5l) were placed in plastic vats and the drainage water was recovered in vessels (17l). The experimental design was in complete blocks with six replications. Samples of the drainage water were collected every 2 weeks for analysis. The pots were fertilized every week (400 mg/Ll of N) and growth parameters were statistically analyzed by ANOVA. The chemical analysis of the residues proves that they contain weak concentrations in organic contaminants. There is an accumulation of NO 3 in drainage water following the fertilization; the same applies to sulfates and potassium. On the other hand, heavy metals are not released in important concentrations and so the lead, zinc, manganese, and copper contents do not exceed the desirable limits. Moreover, the Physocarpus plants produced in CSS substrates had a growth significantly larger than those plants produced in FBF or CDS substrates. The three organic residues do not constitute a risk of pollution for the environment.

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A commercial inoculum of Glomus intraradices Schenk and Smith, a vesicular–arbuscular mycorrhizal fungus, has been used with the objective of studying its effects on rooting and on subsequent growth of two woody ornamental plants (Juniperus Sabina `Blue Danube' and Cornus sericea `Coloradensis'). This inoculum, called Mycorise™, is produced by Premier Peat Co. (Rivière-du-Loup, Québec, Canada) and it contains one propagule/g of Glomus intraradices. The cuttings's rooting media was mixed in order to contain 0%, 10%, 20%, 40%, or 80% of inoculum. Hardwood cuttings have been inserted in 65-ml cells and put under a mist until good rooting. For both species used, presence of inoculum in rooting media has not given significant effects during the rooting stage of cuttings, but has given some during the following stage of growth in 6-L containers. The growth of young mycorrhized plants of Juniperus was up to 50% greater than the control after the first season of growth. The young plants of Cornus have only showed a tendency to have a higher growth. Moreover, several mineral elements (N, P, Ca, Mn, Zn) were present at higher concentrations on mycorrhized plants. For roots colonization by the fungus and growth results, the inoculum proportion of the rooting media the most appropriate for Juniperus Sabina `Blue Danube', a slow-rooting species, was 40%, and the most appropriate for Cornus sericea `Coloradensis', a quick-rooting species, was 20%.

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To examine injuries caused by freezing temperature, six woody plants were placed under temperatures ranging from 0 to 20C. Control plants were placed at 0 or –2C, depending on the field sampling period. Freezing tests were done three times (September, October, and November) during the fall. In 1992, six species were tested: Genista tinctoria `Lydia', Parthenocissus `Veitchii', Weigela × florida `Variegata', Spiraea japonica `Shirobana', Spiraea japonica `Coccinea', and Arctostaphylos uva-ursi. After testing, all plants were stored at –2C for the remainder of the winter. The following May, plants were repotted into containers. Effects of freezing temperatures on plant growth were recorded at the end of the following summer. Preliminary results indicate that the most sensitive species to cold temperatures were Parthenocissus `Veitchii' and Arctostaphylos uvaursi. Plants of these two species did not survive the summer. However, for the third sampling period, Parthenocissus `Veitchii' (–18C) had better cold hardiness than A. uva-ursi (–9.5C). Genista tinctoria `Lydia' appeared to have the same cold hardiness (–10C) for the three sampling periods. The last three species had shown increasing cold hardiness beginning at around –8C in September to about –18C in November.

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Large spaces are required to eliminate waste by burying and this method is very costly. The horticulture use of waste seems to be one of the best optional methods of disposal. This study was performed to evaluate the effects of fresh bio-filters (FBF), composted sewage sludges (CSS), and composted de-inked sludges (CDS) on growth of three woody ornamental species (Spiraea japonica `Little Princess', Spiraea nipponica `Snowmound', and Physocarpus opulifolius `Nanus') produced in containers. Three fertilization regimes (N at 200, 400, and 600 mg·L–1 in the form of soluble fertilizer 20–20–20) were applied weekly onto containers during 3.5 months. Plants were potted in 10 substrates. The control substrate contained 4 peatmoss: 5 composted conifer bark: 1 fine crushed gravel (by volume). In the other nine substrates, peatmoss was partially substituted by one of the three organic residues (10%, 20%, or 30% of FBF, CSS, or CDS). The experimental design was a split-split-plot with four replicates and two samples by treatment. Chemical analysis of the organic residues proved that the fertilization value of CSS was greater than the other residues and heavy metals are below the undesirable limits for the three residues. The amount of available major mineral elements in these residues is too low to satisfy the mineral nutrient needs of plants. In addition, there is a linear effect of the fertilization on plant growth. The CDS required a high dose of the fertilizer (600 mg·L–1) which may be due to the immobilization of N. The 10% proportion of FBF and CDS, combined with the other materials, was the most adequate proportion and did not reduce the growth of plants (height, aerial, and root dry matter). However, CSS can be used with a high proportion (20%) especially for Spiraea japonica `Little Princess'.

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Six fertilization programs were applied to three woody plants: Physocarpus opulifolius `Nanus', Spiraea × bumalda `Gold flame', and Weigela florida `Rumba'. The objective of this study was to determine fertilization programs best adapted to container woodyplant production. Treatments were: 1) Nutricote (5 g/liter of growth medium) + weekly fertigation of 20N–20P–20K (300 mg N/liter); 2) Coïc-LeSaint solution for each irrigation; 3) Nutricote + weekly fertigation of liquid 9N-9P–9K (300 mg N/liter); 4) fertigation with complete nutrient solution (125 mg N/liter); 5) Polyon + weekly fertigation of 20N–20P–20K (300 mg N/liter); and 6) Nutralene + weekly fertigation of 20N–20P–20K (300 mg N/liter). The experiment took place between 25 June 1991 and 15 Aug. 1992. Results show that, independent of species, plants given fertilization program 4 had lower plant height (57 cm) and stem dry weight (97 g) than plants under other treatments, the average for each parameter being 72 cm and 127 g, respectively. Plant height was highest in Physocarpus with treatment programs 2, 4, 5, and 6. Weigela had greater growth under program 2, while Spiraea had more growth with programs 1, 3, and 6. Consequently, differences exist between optimum fertilization programs used for each species studied.

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The most widespread deformation observed in container production is root circling. Consequently, root circling often reduces growth, root regeneration, and tree anchorage at transplanting time. The objectives of this study were to test the effectiveness of Cu(OH)2 lined containers on restriction of root tips, tree growth, and potential root regeneration (PRR). Two species were used in this study: Fraxinus pennsylvanica and Acer saccharinum. Species were grown for one season in containers lined with one of six combinations of polymer (P) (0, 30, and 60 g·m–2) and copper (Cu) (0%,0.4%, and 0.8%) -coated fabric. Two other treatments were included as controls: a plastic container and a fabric container. Seedlings of each species were harvest twice: at the first season and after being transplanted from 10- to 75-liter containers. Treatments were randomized in complete blocks with six repetitions. Results of root circling length and dry weight indicate good restriction of root tips for two combinations (30 g of P/m2–0.8% Cu; 60 g of P/m2–0.8% Cu) for all species. However, treatments did not cause any reduction in stem height, trunk diameter, or stem and root dry weight. At the end of the transplanting season, PRR was greater for two combinations (30 g of P/m2–0.8% Cu; 60 g of P/m2–0.8% Cu), especially for green ash. No significant differences were observed between a plastic fabric and the two treatments cited for the other growth parameters. No phytotoxic symptoms were observed throughout the experiment.

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The objective of this study was to determine the persistence and leaching of the herbicide oxadiazon in five substrates. The substrate mixtures consisted of the following: peatmoss, compost, and sand in the following proportions: 1:1:0, 3:3:2, 1:1:2, 1:1:6, and 0:0:1 in 5-liter containers. Rates of oxadiazon used were 4 and 8 kg a.i./ha on two separate split-split plots. Each experimental design had three factors: five substrates, four harvest times (24 h; 1, 2, and 3 months) and five soil depths (0–2, 2–4, 4–6, 6–8, 8– cm). Only herbicide persistence and leaching from the various substrates were investigated in this experiment; therefore, we did not remove plant material. Substrate oxadiazon residues were determined by gas chromatography analysis, and it was shown that leaching was more evident in media with a lower percentage of organic matter. In addition, oxadiazon did not leach below 4 cm in conventional substrate (1 peatmoss: 1 compost: 1 sand, respectively). The persistence of oxadiazon was affected by soil composition and herbicide persisted more in substrates with great percentage of organic matter.

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The objective of this study is to determine the phytotoxicity and efficiency of oxadiazon and sethoxydim used as herbicide in the production of four species of woody ornamental plants grown in containers. Four species were used: Cornus alba `Argenteo Marginata', Weigela florida `Rumba', Prunus x cistena and Thuja occidentalis `Woodwardii'. Six herbicide treatments were used (oxadiazon at 0,4 and 8 Kg (a.i.)/ha; sethoxydim at 0.000, 0.276 and 0.552 Kg (a.i.)/ha) and two controls were added (weeding and unweeding). The eight treatments were included in a complete block design replicated six times. This project was started in July 1993 and was conducted for three months. If phytotoxic symptoms were present on plants they were recorded and their effects on growth was measured. At the end of the experiment, weeds present in pots were identified, counted and their growth measured. Preliminary results showed that oxadiazon applied at rates of 4 and 8 Kg (a.i.)/ha had a good efficiency weed control in container production. Sethoxydim applied at rates of 0.276 and 0.552 Kg (a.i.)/ha had a good grass control. The two herbicides did not show phytotoxic symptoms on the for species used. The effects of herbicides on plant growth will be presented.

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Root system growth in limited volume containers can have important consequences on stem growth and root morphology. The most widespread deformation observed is root circling. Consequently, root circling often reduces growth, root regeneration and tree anchorage at transplanting time. The objective of this study is to restrict root tips. Three tree species were used in the study; Fraxinus Pennsylvanica, Acer saccharinum and Malus baccata. All species were grown in containers lined with one of six combinations of polymer (P) (0, 30 and 60 g/m2 and copper (Cu) (0, 0.4 and 0.8%) coated fabric. Two other treatments were included as controls: a plastic container and a fabric container. Treatments were randomized in complete blocks with six repetitions. Preliminary results of root circling length and dry weight indicate good restriction of root tips for two combinations (30 g of P/m2 - 0.8% Cu; 60 g of P/m2 - 0.8% Cu) for all species. However, treatments did not cause any reduction in stem height, trunk diameter or stem and root dry weight. Phytotoxic symptoms were not observed throughout the experiment.

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