Black Plastic Containers Research Articles

Nitrogen Rate, Irrigation Frequency, and Container Type Affect Plant Growth and Nutrient Uptake of Encore Azalea ‘Chiffon’

One-year-old liners of Encore® azalea ‘Chiffon’ (Rhododendron sp.) were transplanted in Apr. 2013 into two types of one-gallon containers: black plastic container and paper biodegradable container. Azalea plants were fertilized with 250 mL of nitrogen (N) free fertilizer solution twice weekly plus N rate of 0, 5, 10, 15, or 20 mm from ammonium nitrate (NH4NO3). All plants were irrigated with the same total volume of water through one or two irrigations daily. Plant growth and N uptake in response to N fertilization, irrigation frequency, and container type were investigated. The feasibility of biodegradable paper containers was evaluated in 1-year production of Encore® azalea ‘Chiffon’. Paper biocontainers resulted in increased plant growth index (PGI), dry weights (leaf, stem, root, and total plant dry weight), leaf area, and root growth (root length and surface area) compared with plastic containers using N rates from 10 to 20 mm. Biocontainer-grown plant had more than twice of root length and surface area as plastic container–grown plant. Leaf SPAD reading increased with increasing N rate from 0 to 20 mm. One irrigation per day resulted in greater PGI, root dry weight, root length, root surface area, and root N content than two irrigations per day. Higher tissue N concentration was found in plants grown in plastic containers compared with those grown in biocontainers when fertilized with 15 or 20 mm N. However, N content was greater for plants grown in biocontainers, resulting from greater plant dry weight. The combinations of plastic container and one irrigation per day and that of 20 mm N and one irrigation per day resulted in best flower production, 21.9 and 32.2 flowers per plant, respectively. Biocontainers resulted in superior vegetative growth of azalea plant compared with plastic containers with sufficient N supply of 10, 15, and 20 mm.

Substrate Temperature in Plastic and Alternative Nursery Containers

The green industry has identified the use of biodegradable containers as an alternative to plastic containers as a way to improve the sustainability of current production systems. Field trials were conducted to evaluate the performance of four types of 1-gal nursery biocontainers [keratin (KR), wood pulp (WP), fabric (FB), and coir fiber (Coir)] in comparison with standard black plastic (Plastic) containers on substrate temperature, water use, and biomass production in aboveground nurseries. Locations in Kentucky, Michigan, Mississippi, and Texas were selected to conduct experiments during May to Oct. 2012 using ‘Green Velvet’ boxwood (Buxus sempervirens × B. microphylla) and ‘Dark Knight’ bluebeard (Caryopteris ×clandonensis) in 2013. In this article, we were focusing on the impact of alternative container materials on hourly substrate temperature variations and plant growth. Substrate temperature was on an average higher (about 6 °C) in Plastic containers (about 36 °C) compared with that in WP, FB, and Coir containers. However, substrate temperature in KR containers was similar to Plastic. Substrate temperature was also influenced by local weather conditions with the highest substrate temperatures recorded in Texas followed by Kentucky, Mississippi, and Michigan. Laboratory and controlled environment trials using test containers were conducted in Kentucky to evaluate sidewall porosity and evaporation loss to confirm field observations. Substrate temperature was similar under laboratory simulation compared with field studies with the highest substrate temperature observed in Plastic and KR, intermediate in WP and lowest in FB and Coir. Side wall temperature was higher in Plastic, KR, and FB compared with WP and Coir, while side wall water loss was greatest in FB, intermediate in WP and Coir, and lowest in plastic and KR. These observations suggest that the contribution of sidewall water loss to overall container evapotranspiration has a major influence on reducing substrate temperature. The porous nature of some of the alternative containers increased water use, but reduced heat stress and enhanced plant survival under hot summer conditions. The greater drying rate of alterative containers especially in hot and dry locations could demand increased irrigation volume, more frequent irrigation, or both, which could adversely affect the economic and environmental sustainability of alternative containers.

Microbiological assessment of well water at different durations of storage.

Water is the most universally used single necessity of life. To attain a safe water quality to various communities, an understanding of water microbiology and chemistry is therefore imperative. In this study, well water at different storage durations of 0, 2, 4, 6 and 8 weeks were assessed for bacteriological quality using standard microbiological techniques. Black barrel-shaped plastic containers (300 liter capacity) were used for different storage durations. Water samples at the different storage durations were collected from each corresponding containers. Sterile swabs were used to sample the sides and bottom of the storage containers to determine the prevalence of specific bacteria present in the samples. The results obtained showed that 0 week storage had the highest (100.00 CFU mL(-1)) coliform counts while the lowest (28 CFU mL(-1)) was obtained for 8 weeks of storage. Escherichia coli were not found in 4, 6 and 8 weeks old water. 0 and 2 weeks old water contained E. coli and the mean values were 1.80 x 10(4) +/- 0.03 and 1.43 x 10(4) +/- 0.01 CFU mL(-1), respectively (p < 0.05). Salmonella organisms were found in the 0 week old water but absent in the 2, 4, 6 and 8 weeks old water. Shigella count (62.33 x 10(2) +/- 45.30 CFU mL(-1)) was highest in 4 week old water while the lowest (11.0 x 10(3) +/- 1.00 CFU mL(-1)) was found in 6 week old water (p < 0.05). Zero week old water had the lowest significant (p < 0.05) value of 0.35 x 10(4) +/- 0.05 CFU mL(-1) for mesophilic bacteria and the highest value of 50.00 x 10(4) +/- 10.0 CFU mL(-1) was recorded in the 8 weeks old water. Sides and bottom samples were contaminated with coliforms, E. coli, Salmonella and Shigella organisms. It was concluded that the variously stored well water samples were contaminated with bacteria and the values obtained were above the recommended standards by the World Health Organization (WHO).

Container Type and Overwintering Treatments Affect Substrate Temperature and Growth of Chanticleer® Pear (Pyrus calleryana ‘Glen's Form’) in the Nursery

The container most used for nursery tree production is black plastic (BP). High substrate temperatures occurring in BP can injure or kill roots; BP-grown trees often develop circling and malformed roots. Root injury sustained during production may negatively affect tree health after planting in the landscape. Many containers are available for nursery production, but few studies have examined the merits of alternative container types for production. We compared the growth of Pyrus calleryana Decene. ‘Glen's Form’ (Chanticleer®) in three container types: black plastic, Root Pouch® (RP) and Smart Pot® (SP), over two growing seasons and under two overwintering treatments (consolidated or lined out). After the first growing season, there were no differences in height or dry leaf, shoot and root weight among the three containers. Following the second growing season, caliper, height, leaf area, percent leaf moisture, and root ball quality differed among container type. After the 2010–2011 winter, consolidated trees produced larger root and shoot systems (35.3 and 36.4%, respectively) than trees that were lined out. Substrate temperature maxima and fluctuations during winter and summer were greatest for BP containers compared to RP and SP. The potential advantages of producing trees in fabric containers merit consideration from nursery producers.

Propagation Container Type, Time in Container, and Root Pruning Affect Root Development of Young Acer rubrum

Numerous propagation containers have been developed in an effort to reduce root deformities on tree and shrub nursery stock. Root attributes in containers are also impacted by retention time in the container. A popular shade tree, Acer rubrum L., was grown in 6 different propagation containers for two time periods and root pruned or not before shifting to 10 liter (3 gal) black plastic containers to evaluate root system quality. Root pruning when shifting into larger 10 liter (3 gal) containers resulted in more structural roots, adventitious roots from cuts, and woody second-order roots, growing closer to the substrate surface due to a reduced angle of departure from the trunk. Root pruning improved root system quality by increasing the number of straight, radially-oriented roots growing from all propagation containers except for Ellepots placed in contact with other Ellepots which had an equivalent high number of straight roots without pruning. By many measures, all propagation container types produced nearly equivalent root systems provided root balls were mechanically pruned by shaving off roots on the periphery when shifting to 10 liter (3 gal) containers. However, root pruning when shifting had no effect on mortality or trunk diameter growth in 10 liter (3 gal) containers. Without root pruning, the propagation container type and retention time had a large influence on root morphology in 10 liter (3 gal) containers.

Arbuscular mycorrhizal fungi alleviate growth of Ulmus parvifolia Jacq. at suboptimal planting depths

Planting depth (location of root collar in relation to substrate surface grade) varies in the container production industry. Optimum planting depth varies for different species. Most container-produced plants are grown in a soilless media to allow better aeration and drainage conditions, so the effects of planting depth observed in landscape establishment may be different from those seen in container-production. This study tested if inoculation with arbuscular mycorrhizal fungi (AMF) would enhance the tolerance of container-grown Ulmus parvifolia Jacq. (lacebark elm) to above and/or below grade planting depths. The AMF plants and non-AMF plants were planted into 2.1L black plastic containers with their root collars at substrate surface (grade), 3cm above grade, 1cm above grade, 1cm below grade, or 3cm below grade under greenhouse conditions. Growth (stem diameter, total plant dry mass) and physiological responses (leaf nutrient concentration, chlorophyll concentration, total antioxidant and nitrate reductase activities, and total phenolic content) were measured. In general, AMF plants had greater growth when planted above or below grade when compared to non-AMF plants at the same planting depth, but this was not correlated with enhanced nutrient tissue levels. Non-AMF plants planted at grade had greater growth than AMF plants at grade. Planting at grade resulted in optimum growth for U. parvifolia. Poor transplanting techniques during container production (above or below grade) were partially alleviated by inoculating plants with AMF.

The Effect of Solar Loading on Soil Temperatures and Developmental Variation in Greenhouse Studies

Water is the single most limiting factor of crop yield. A high throughput method of screening sorghum for transpiration efficiency (TE) might allow selection for plants able to maintain production in semiarid regions having few irrigation resources. A high throughput TE assay was characterized. We hypothesized that variation in solar radiation absorbed by containers could introduce soil temperature variation and influence measured TE. To test our hypothesis, two sorghum lines, Liang Tang Ai (High TE) and TX‐7078 (Low TE), were grown in either conventional black plastic or in insulated containers and TE determined as biomass/water transpired. Soil temperatures in the sealed conventional thermoplastic containers exceeded 50°C and plants developed more slowly than those grown in insulated containers. Liang Tang Ai showed 30% greater TE as compared to TX‐7078 when grown in insulated containers, but any potential TE differences were masked by supra‐optimal temperatures in the conventional black plastic containers. Our results showed that the effects of solar radiation loading can lead to high soil temperatures and must be considered when designing TE screening experiments or other physiological studies.

Can Growth of Seed-propagated Oaks be Predicted before Lining out in Nursery Rows?

Growth rates of nursery-grown oaks (Quercus L.) vary considerably, and many oak species are not commonly grown because of slow growth when young. A method for rapid screening of young oak seedlings to predict potential growth in a production nursery was investigated. Acorns from single maternal trees of four Virginia-native oak species, Quercus montana Wild. (chestnut oak), Quercus palustris Münchh. (pin oak), Quercus velutina Lam. (black oak), and Quercus alba L. (white oak) were collected in Blacksburg, VA, in the fall of 1999 and subjected to stratification (moist-chilling) at 5C (41F). Single acorns were then planted in individual cells of 50-cell liner trays and grown in a heated greenhouse until individual seedlings had set first buds. Height at first budset was recorded for individual seedlings. Trees were then transplanted into 3.8 liter (#1) black plastic containers and grown outdoors in Blacksburg, VA, until June 2001, when they were transplanted to field soil. All trees were grown in the ground for three additional growing seasons, and final trunk diameters were measured in February 2004. Height at first budset was not related to trunk diameter at the end of the experiment for any species and was only weakly related to final height for black oak. Trunk diameter of seedlings when planted in field beds 1.5 years from seed was related to trunk diameter at the end of the experiment for all species, but little variation was explained by the relationship for chestnut oak or black oak. Plant height at field planting was not as predictive as trunk diameter for final trunk diameter, except for black oak. The utility of screening a group of oak seedlings at the liner stage for subsequent growth potential is species-specific. Screening white oak by trunk diameter appears especially promising.

Estudo do comportamento de oviposição no campo e o ciclo de vida de Aedes albopictus (SKUSE, 1894) (Diptera: Culicidae) em laboratório

The objective of this work was to show the substrates preference for oviposition of Ae. albopictus in the field, and its developmental cycle in laboratory. Insects were distributed in nine black plastic containers in the field, next to chicken coops, pigsties and jaboticaba trees. Paper coffee filters, wrapping paper cones and palettes of eucatex were, simultaneously, placed in every container. The observations were conducted twice a week for 120 days. After counting, eggs were transferred to disposable plastic cups, with 500mL capacity. Inside them, 350 mL of water were placed in order to propitiate the eclosion of larvae. Every plastic cup was properly identified with the date and type of substrate, and daily remarks were made for a 60 days period. We observed 29 postures in the field: nine in wrapping paper, nine in filter paper, and 11 in palettes. The average of eggs was 15.9 per oviposition. The larvae eclosion average was 11.2 and the adult development average was 9.9 per oviposition. The number of male and female insects was approximately one to one. There was no significant difference of oviposition of Ae. albopictus between the studied substrates. In the laboratory, the daily average of eggs per female was 2.09 ± 0.31. The incubation of the eggs lasted for 4.0 days. The average duration of larval instars was 1.4, 1.2, 1.3 and 2.7 days, respectively to 1°, 2°, 3° and 4° instars. The pupae instar lasted for 2.1 days. The average life expectancy for males and females was 60 and 75 days, respectively.

A GRAVIMETRIC APPROACH TO REAL-TIME MONITORING OF SUBSTRATE WETNESS IN CONTAINER-GROWN NURSERY CROPS

A GRAVIMETRIC APPROACH TO REAL-TIME MONITORING OF SUBSTRATE WETNESS IN CONTAINER-GROWN NURSERY CROPS

Optimum Nitrogen Fertilization for Production of Containerized Raphiolepis × delacourii ‘Snow White’

Abstract Rooted stem cuttings of ‘Snow White’ raphiolepis (Raphiolepis × delacourii Andre ‘Snow White’) were grown in 3.8-liter (#1) black plastic containers containing a pine bark:sand (8:1, by vol) substrate. Plants were fertilized at every irrigation, for 17 weeks, with a 4:1:2 nitrogen (N):phosphorus (P):potassium (K) nutrient solution containing N at 20, 60, 100, 140, 180, 220, or 240 mg·L−1 (ppm) supplied as ammonium nitrate (NH4NO3). Maximum top and root dry weights were achieved with N at 145 mg·L−1. Substrate solution electrical conductivity increased linearly with increasing nitrogen application rate (NAR) with maximum growth occurring at 1.28 dS·m−1, whereas substrate solution pH decreased linearly with increasing NAR with a pH of 5.3 at 145 mg·L−1. Increasing the N rate beyond 145 mg·L−1 had minimal effect on top or root dry weight. Leaf area peaked at a NAR of 171 mg·L−1 with a plateau at 524 cm2. Leaf area increased 275% as the NAR increased from 20 to 171 mg·L−1. Specific leaf area increased linearly with increasing NARs. Carbon allocation between tops and roots was unaffected by NARs from 60 to 280 mg·L−1. Root:top ratio decreased 56% between the pooled NARs (60 to 240 mg·L−1) and N at 20 mg·L−1. Leaf area ratio increased linearly with increasing NARs. Foliar mineral nutrient concentrations of N, P, and sulfur increased linearly with increasing NAR, whereas concentrations of K, calcium, magnesium, and copper responded quadratically to increasing NARs. Top growth increased from inadequate at a NAR of 60 mg·L−1 to optimum at 145 mg·L−1, whereas root growth was relatively similar over the same range. At 145 mg·L−1, mineral nutrient concentrations of the top are well within or exceed accepted levels reported, and growers can expect rapid growth of rooted cuttings.

Cyclanilide Alterations In Growth Of Five Landscape Plant Species During Container Production Are Location Specific

Abstract Five species of tropical and warm temperate shrubs, bush morning glory (Ipomoea carnea N. von Jacquin subsp. fistulosa (K. von Martinus ex J. Choisy) D. Austin), Indian hawthorn (Raphiolepis indica (L.) J. Lindley), tropical hibiscus (Hibiscus rosa-sinensis L. ‘Brilliantissima’), jatropha (Jatropha integerrima N. von Jacquin), and nandina (Nandina domestica C.P. Thunberg), were grown in 2.8-liter (#1) black plastic containers at two contrasting nursery locations and regimes. In College Station, TX, plants were grown in full sun under high fertility conditions, while in Dallas, TX, plants were grown under 40% light exclusion and a lower fertility level. Plants at each location were sprayed to runoff, either once or twice, with a distilled water only control, a Latron B-1956 spreader sticker surfactant at 0.063 mg/liter (0.063 ppm) in distilled water, or cyclanilide [1-(2,4-dichlorophenyaminocarbonyl)-cyclopropane carboxylic acid] at 56, 112, or 223 mg/liter (56, 112, or 223 ppm, respectively) with the Latron surfactant in a distilled water carrier. Half of the plants in all treatments received a single application, while the other half received a second application two to three weeks later. Although growth responses and release of dormancy varied among species and with cyclanilide concentration, plants of most species had greater release of lateral buds from a dormant or quiescent state under the high irradiance and fertility conditions in College Station, compared to the lower irradiance and fertility conditions in Dallas. However, phytotoxicity symptoms as evidenced by lower quality ratings were also more prevalent in College Station. Phytotoxicity was moderate to severe on nearly all jatropha and tropical hibiscus plants exposed to cyclanilide. Toxicity symptoms and significant growth reductions were present on several species at 112 or 223 mg/liter (112 or 223 ppm, respectively). A second application usually increased the effects on growth responses at all concentrations and often induced phytotoxicity symptoms at 56 mg/liter (56 ppm). The disparate responses between the two locations suggest the importance of local growing conditions on the potential efficacy and predictability of responses to cyclanilide applications.

Planting Depth and Mulch Thickness Affect Establishment of Green Ash (Fraxinus Pennsylvanica) and Bougainvillea Goldenraintree (Koelreuteria Bipinnata)

Most available information on the effects of planting depths for trees is anecdotal. Testing of interactions with other important cultural practices implemented during landscape establishment is lacking. Green ash (Fraxinus pennsylvanica H. Marshall), a hypoxia-tolerant species, and bougainvillea goldenraintree (Koelreuteria bipinnata A.R. Franchet), a hypoxia-intolerant species, were grown from seed in 2.3 L (#1) containers, which were later transplanted to 9.3 L (#3) black plastic containers and grown to a marketable size. Root collars of the plants were maintained level with the surface of the substrate. Green ash (1 May 2001) and bougainvillea goldenraintrees (27 April 2001) were transplanted to clay soil field plots with the root collars at 7.6 cm (3 in.) above soil grade, at grade, or 7.6 cm (3 in.) below grade. Planting depths for each species were in factorial combinations with 0, 7.6, 15.2, or 22.9 cm (0, 3, 6, or 9 in.), respectively, of pine bark mulch covering 0.74 m2 (8 ft2) of soil beneath each tree. After 2 years, survival of bougainvillea goldenraintrees planted below grade was one-third that of those planted at or above grade. Survival and trunk diameter responses interacted with planting depth and mulch thickness for green ash. Planting below grade in combination with mulching reduced survival of green ash 25% to 50% after 3 years. Mulch applications reduced trunk diameters of green ash trees planted at or above grade. Mean soil water potentials were less negative with 7.6 cm (3 in.) of mulch (­5.8 kPa) compared to bare soil (­9.1 kPa), but increasing the mulch thickness to 22.9 cm (9 in.) inhibited penetration of irrigation water/rainfall (­16.2 kPa). These data suggest that planting with the root collar at or above grade enhances survival and growth potential of green ash and bougainvillea goldenraintree relative to planting below grade and that mulch applications should be only at thin layers sufficient to inhibit weeds. Bougainvillea goldenraintrees were more susceptible to the adverse effects of below-grade installation and excess mulch applications than were green ash trees.

Irrigation and Container Type Impact Red Maple (Acer rubrum L.) 5 Years After Landscape Planting

The objective of this research was to compare red maple (Acer rubrum L.) root and canopy growth 5 years after landscape planting from seven different container designs maintained under two irrigation regimes. Trees planted from low-profile air root-pruning containers had larger trunks 5 years after landscape installation than those planted from regular air root-pruning containers, wood boxes with cupric hydroxide coating, or standard black plastic containers with cupric hydroxide coating. Despite significant differences in root weight and amount of deflected roots among container types when trees were planted in the landscape, root number, root depth, and radial root distribution around the trunk were identical 5 years after planting from all container types. However, frequency of irrigation in the first 24 weeks following planting had a significant effect on root system structure even 5 years later. Frequent irrigation resulted in larger trunks, more roots, greater root cross-sectional area, and a more uniform radial root distribution. The increase in root growth on frequently irrigated trees occurred exclusively in the top 30.5 cm of soil. Codominant stems 4 years after planting were equally common, regardless of production method and irrigation treatment. With the exception of the low-profile air root-pruned container, the reduction in root defects on the outer surface of root balls grown in containers designed to reduce defects appeared to provide no measurable benefit to trees 5 months or 5 years after planting into the landscape. Irrigation management after planting had a more positive impact on landscape root growth and distribution than container type.

Evaluating Recovery of Cupressaceae Taxa After Flooding at Contrasting Temperatures

Abstract Chamaecyparis are ornamental plants that are used extensively in temperate-zone landscapes worldwide. However, due to their low tolerance to environmental stresses Chamaecyparis often perform poorly in urban landscapes. The objective of this research was to evaluate rootstocks of selected Cupressaceae taxa to determine their adaptability to poor drainage and high temperatures found commonly in urban landscapes. To accomplish this objective, 10 taxa (Chamaecyparis, Platycladus, Thuga spp., and x sCupressocyparis leylandii) were grown in 2.8 liter (#1) black plastic containers with a pinebark:sand (8:1 by vol) medium for 19 weeks in two greenhouses with 9/15 hr day/night temperatures of either 22/18C (72/64F) or 30/26C (86/79F). Half the plants in each greenhouse were flooded for 4 weeks. Root relative growth rate (RGR) was a better indicator of plant performance under flooded conditions compared to shoot RGR. At 22/18C (72/64F), root RGR of Chamaecyparis thyoides and Thuja ‘Green Giant’ only declined 10% and 11% between nonflooded and flooded plants, respectively. Chamaecyparis obtusa and x Cupressocyparis leylandii had the largest percentage decline in root RGR from nonflooded to flooded plants with 71% and 213%, respectively. Chamaecyparis thyoides had the highest root RGR at 30/26C (86/79F) in both nonflooded and flooded conditions with a 19% decrease in root RGR between nonflooded and flooded. Chamaecyparis lawsoniana and T. ‘Green Giant’ were ranked 2 and 3 in flooded conditions at 30/26C (86/79F); however, percentage decline increased to 43% and 46%, respectively. At this temperature, the remaining seven taxa had greater than 50% decline in root RGR in flooded conditions compared to nonflooded plants. In nonflooded conditions, shoot and root RGR of all species decreased from 22/18C (72/64F) to 30/26C (86/79F) except for Chamaecyparis thyoides. The shoot and root RGR of Chamaecyparis thyoides grown in 22/18C (72/64F) and 30/26C (86/79F) were similar in nonflooded conditions. Chamaecyparis thyoides demonstrated excellent tolerance to flooding and temperature and could be a desirable understock for other Chamaecyparis when grown in poorly drained locations.

Origin of Multiple Trunks Affects Crapemyrtle Posttransplant Establishment

Bare-root 17.5-inch-tall (44.45-cm) `Sarah's Favorite' crapemyrtle (Lagerstroemia indica L.) liners were grown in #3 [2.75-gal (10.4-L)] black plastic containers and trained to one, three, or five trunks by one of two methods. Half of the plants were established from multiple liners with each trained to form one of the trunks. The others were established by planting a single liner in each container, pruning them back to within 2 inches (5.1 cm) from the substrate surface, and then training elongating buds or adventitious shoots to the desired number of trunks. Once plants reached a marketable size they were transplanted to a landscape for two growing seasons to determine the effects of the treatments on trunk survival or growth uniformity in the landscape. The study was replicated in time with containerized `Basham's Party Pink' crapemyrtle liners, but only grown in the field for 1 year. Growth and quality differences were minimal at the end of nursery production for either clone, thus favoring recommendation of whichever treatment would be most economical to produce the desired growth form. However, in the landscape phase, survival of `Sarah's Favorite' crapemyrtle and growth and uniformity of `Basham's Party Pink' crapemyrtle were greater for several growth measures when multiple trunks were produced by training stems of the same plant as opposed to planting multiple liners. Trunk survival was generally good for three or fewer trunks, but significant losses often occurred when the planting units had five trunks, especially when grown from multiple liners. Growth and survival differences among treatments were more pronounced with increasing trunk number and the longer the planting units were in the field (landscape).

Species Responses to Accelerator Grower vs. Black Plastic Containers

Five species of trees, Fraxinus velutina Torr., Pistacia chinensis Bunge, Platanus occidentalis L., Quercus virginiana Mill., and Ulmus parvifolia Jacq., were first grown in 0.45-L conventional black plastic liner containers, then transplanted to 25-L black plastic containers and grown to a marketable size. The same species were grown in similar-size, open-bottom, air-root pruning, cylindrical, aluminum (Accelerator) containers filled with the equal volumes of media. Plant growth characteristics, root-zone temperatures, and media moisture status were measured. Growth of Q. virginiana was reduced in Accelerator liner containers compared to conventional black plastic liners. Accelerator liners did eliminate circling and deflection of roots at the bottom of the liner containers. Growth of U. parvifolia, F. velutina, and Q. virginiana were similar in the larger 25-L Accelerator and black plastic containers, while growth of P. chinensis and P. occidentalis were greater in Accelerator containers than in conventional black plastic containers. Root-zone temperatures, particularly at the periphery of the rootball, were significantly reduced on warm days in Accelerator containers compared to those in black plastic containers. Media in Accelerator containers were slightly drier than that in black plastic containers.

Accelerator™ Containers Alter Plant Growth and the Root-zone Environment

Abstract Five species of trees, Fraxinus velutina Torr., Pistacia chinensis Bunge, Platanus occidentalis L., Quercus virginiana Mill., and Ulmus parvifolia Jacq., were first grown in conventional black plastic liner containers (0.45 liter, 0.41 qt) then transplanted to black plastic containers filled with 25 liters (7 gal) of substrate and grown to marketable size. The same species were grown in Accelerator liners and then transplanted to open bottom, air-root pruning, cylindrical, aluminum (Accelerator) containers filled with equal volumes of substrate. Plant growth characteristics, root-zone temperatures, and substrate moisture status were measured. As with many container technologies, responses were species dependent. Growth of Q. virginiana was reduced in Accelerator liner containers compared to conventional black plastic liners. Root coverage on the periphery of the rootballs were reduced on U. parvifolia grown in 25 liter (7 gal) containers compared to those in black plastic containers. Growth of U. parvifolia, F. velutina, and Q. virginiana were similar in the larger black plastic and Accelerator containers. Growth of P. chinensis and P. occidentalis were greater in the larger Accelerator containers than in the larger conventional black plastic containers. Root-zone temperatures, particularly at the periphery of the rootball, were significantly reduced on warm days in Accelerator containers compared to those in black plastic containers. Substrate in Accelerator containers were slightly drier than that in black plastic containers.

325 Evaluation of `Meeker' Red Raspberry Freeze Tolerance using Whole-plant Growth and Root Electrolyte Leakage Viability Tests

In Spring 1996, `Meeker' red raspberry root cuttings were planted into a sandy loam soil in 30 cm tall x 27 cm diameter black plastic containers. During Mar. 1997, a second bottomless container was placed over the overwintering canes of half of the plants. The second container was filled with the same sandy loam soil to simulate ridging of the plants. All plants were grown using standard cultural practices on an outdoor, gravel nursery bed. Freeze tolerance of potted whole plants and excised root sections was measured at 5 °C intervals between -5 and -20 °C in a series of laboratory freeze tests conducted during Jan. 1998. Electrolyte leakage data were used to calculate the index of injury for excised roots while whole-plant response to freezing was determined by measuring the subsequent growth of floricane lateral shoots and of primocanes. After 1 month in the greenhouse, results indicated the dry weight of primocanes harvested from plants that were exposed to -20 °C was 56% of the nonfrozen control primocane dry weight. Primocane dry weight from plants exposed to -5, -10 and -15 °C was not different from the controls. Similar results were obtained for the percent of floricanes that were alive and for the dry weight of laterals produced by these floricanes after 3 months in the greenhouse. The whole-plant freeze test results indicated plants at the lowest temperature, -20 °C, were injured but not killed. Root index of injury of single potted plants averaged 5%, 15%, 29%, and 58% at -5, -10, -15, and -20 °C, respectively.

Effects of Nursery Container Type on Root Growth and Landscape Establishment of Acer rubrum L.

Abstract Trees of red maple (Acer rubrum L.) were planted into seven container types evaluated for their ability to reduce number of roots deflected by the container wall. Seedlings were grown 70 weeks (production phase) in seven container types to a mean trunk diameter of 3.9 cm (1.5 in) and were transplanted into a sandy soil and grown with frequent or periodic irrigation for 24 weeks (landscape phase). There was no effect of container type on total root mass, trunk diameter or height during the production phase. Total deflected root length was less in low-profile plastic containers, chemical root pruning containers, air root pruning containers (ARPC), and wood boxes than in standard black plastic containers (SBPC). Trees produced in the SBPC had the most horizontally-oriented deflected root length while the ARPC and SBPC had the most vertically-oriented deflected root length. Trees grown in the ARPC had less roots on the inside of the root ball than all other container types. Container type did not influence root and shoot growth, but impacted stem water potential in the first five months after transplanting to the landscape. Trees frequently irrigated during the landscape phase had greater trunk diameter, height, and generated more new root mass than those which were infrequently irrigated.