John Ruter - Academia.edu (original) (raw)

Papers by John Ruter

Hortscience, 2015

Sustainable use of water resources is of increasing importance in container plant production as a... more Sustainable use of water resources is of increasing importance in container plant production as a result of decreasing water availability and an increasing number of laws and regulations regarding nursery runoff. Soil moisture sensor-controlled, automated irrigation can be used to irrigate when substrate volumetric water content (u) drops below a threshold, improving irrigation efficiency by applying water only as needed. We compared growth of two Gardenia jasminoides cultivars, slow-growing and challenging 'Radicans' and easier, fast-growing 'August Beauty', at various u thresholds. Our objective was to determine how irrigation can be applied more efficiently without negatively affecting plant quality, allowing for cultivar-specific guidelines. Soil moisture sensor-controlled, automated irrigation was used to maintain u thresholds of 0.20, 0.30, 0.40, or 0.50 m 3 • m L3. Growth of both cultivars was related to u threshold, and patterns of growth were similar in both Watkinsville and Tifton, GA. High mortality was observed at the 0.20-m 3 • m L3 threshold with poor root establishment resulting from the low irrigation volume. Height, width, shoot dry weight, root dry weight, and leaf size were greater for the 0.40 and 0.50 m 3 • m L3 than the 0.20 and 0.30-m 3 • m L3 u thresholds. Irrigation volume increased with increasing u thresholds for both cultivars. For 'August Beauty', cumulative irrigation volume ranged from 0.96 to 63.21 L/plant in Tifton and 1.89 to 87.9 L/plant in Watkinsville. For 'Radicans', cumulative irrigation volume ranged from 1.32 to 126 L/plant in Tifton and from 1.38 to 261 L/plant in Watkinsville. There was a large irrigation volume difference between the 0.40 and 0.50-m 3 • m L3 u thresholds with little additional growth, suggesting that the additional irrigation applied led to overirrigation and leaching. Bud and flower number of 'Radicans' were greatest for the 0.40-m 3 • m L3 u threshold, indicating that overirrigation can reduce flowering. The results of this study show that growth of the different G. jasminoides cultivars responded similarly to u threshold at both locations. Similarities in growth and differences in irrigation volume at the 0.40 and 0.50-m 3 • m L3 u thresholds show that more efficient irrigation can be used without negatively impacting growth.

Hortscience, Sep 1, 2017

Interspecific and intergeneric crosses were performed between species in the genera Baptisia and ... more Interspecific and intergeneric crosses were performed between species in the genera Baptisia and Thermopsis with the goal of creating hybrids with the best qualities of both parents. Baptisia australis (L.) R. Br. was used as both the male and female parent in intergeneric crosses. Thermopsis chinensis Benth. ex S. Moore, T. lupinoides (L.) Link, and T. villosa Fernald & B.G. Schub. were used as male and female parents in both interspecific and intergeneric crosses. Pollen was collected from B. alba (L.) Vent., B. bracteata Muhl. ex Elliott, and B. lanceolata (Walt.) Ell. and used to make interspecific and intergeneric crosses. Putative hybrids were obtained from both interspecific and intergeneric crosses. Interspecific crosses produced a higher percentage of pollinations resulting in seed set and the number of seeds per pollination than intergeneric crosses. Morphological differences between parent species and progeny were evident in putative hybrids resulting from intergeneric crosses between T. villosa and B. australis and T. villosa and B. alba. Most putative hybrids bloomed during the second year after germination. Because seedlings could be obtained from both interspecific and intergeneric crosses, hybrids within and between the genera Baptisia and Thermopsis are feasible. The Fabaceae family contains 670-750 genera and 18,000-19,000 species. Baptisia (commonly called false or wild indigo) and Thermopsis (commonly named false lupine) of the Fabaceae belong to the tribe Thermopsidae, which comprises 46 species in six genera. All species in Thermopsis and Baptisia are herbaceous; they are the only two genera in Thermopsidae that do not have woody species. Thermopsis contains 23 species and has a widespread distribution with species endemic to Asia and much of temperate North America. Although Thermopsis is considered to have originated in central Asia, T. chinensis Benth. ex S. Moore and T. fabacea (Pallas) Candole are thought to have originated in North America and migrated over the Bering Land Strait to Asia. Three Thermopsis species, T. fraxinifolia Nutt. ex M.A. Curtis, T. mollis (Michx.) M.A. Curtis ex A. Gray, and T. villosa Fernald & B.G. Schub., are native to the southeastern United States. Baptisia contains 15-17 species that are endemic to the southeastern and midwestern United States.

Journal of environmental horticulture, Mar 1, 1994

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.


Journal of environmental horticulture, Mar 1, 1992

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.

Transactions of the ASAE, 1999

A two-year study was conducted to determine the growth response of six different wetland/riparian... more A two-year study was conducted to determine the growth response of six different wetland/riparian plant species receiving swine lagoon effluent. Wastewater from the third lagoon of the University of Georgia main swine unit at Tifton, Georgia, was applied to replicates of the species Ilex cassine ('Dahoon Holly'), Cephalanthus occidentalis ('Buttonbush'), Itea virginica ('Virginia Sweetspire'), Spartina patens ('Saltmeadow Cordgrass'), Juncus effusus (Soft Rush), and Panicum hemitomon ('Maidencane'). The plants were grown in open ended steel containers recessed in the soil at a field site so that they received natural weather conditions in addition to applied wastewater. Measurements were taken periodically of plant height, plant width, biomass, leaf area, and N and P content. All six plant species responded to wastewater with increased growth, and were tolerant of the level of wastewater application. It was found that of the broad-leaved species Cephalanthus had the greatest growth response, while of the non-broad-leaved species Spartina had the greatest growth.

Horttechnology, Dec 1, 2013

Hortscience, May 1, 2023

Salvia coccinea is a valuable flowering annual that attracts hummingbirds and bees to the garden,... more Salvia coccinea is a valuable flowering annual that attracts hummingbirds and bees to the garden, but few cultivars are commercially available. There is a limited range of petal colors and no leaf variegation. This research aimed to improve the ornamental value of S. coccinea by inducing mutations with ethyl methanesulfonate (EMS). The standard, red-flowered species was selected for treatment by exposing seeds to 0%, 0.4%, 0.8%, or 1.2% EMS for 8, 12, or 24 hours. The optimal treatment rate was determined to be 1.2% EMS for 8 hours, which generated desirable mutations near the median lethal dose (LD 50). The M 1 population had a 53% germination rate and was completely morphologically uniform. By the M 2 , mutations included differences in leaf shape and flower size in addition to albina, chlorina, virescens, and chimeral chlorophyll changes. A 1% mutation rate was achieved in this breeding program with seven unstable mutations and six stable mutations. The normalized difference vegetation index (NDVI) values were measured to determine differences in chlorophyll content between lethal albina mutations, chartreuse chlorina and virescens mutations, and typical leaf color. Future work will investigate the stability and heritability of chlorophyll variegation by hybridizing these selections with coral-flowered accessions of S. coccinea.

Transactions of the ASABE, 2007

A farm-scale study was conducted from 2000 to 2004 to determine the effectiveness of grass-forest... more A farm-scale study was conducted from 2000 to 2004 to determine the effectiveness of grass-forest vegetated buffers in assimilating nitrogen (N) from overland flow application of swine lagoon effluent. The rationale for the study was that replicated buffer plot studies had shown that vegetated buffers will effectively assimilate N, but it was not known whether or not they would work at a larger scale. The study was conducted on a commercial farm near Tifton, Georgia. Wastewater was pumped from a single-stage anaerobic lagoon to vegetated buffers composed of grass and mature or newly planted pines. The buffers approximated 60 m in length by 90 m in width. The upper 10 m of each buffer was in grass, while the downslope area was in mature or newly planted pines. Six buffers were instrumented for wastewater application and water quality monitoring. Two buffers received wastewater at a 1X rate (600 kg N ha −1 year −1), two at a 3/4X rate (450 kg N ha −1 year −1), and two served as controls. The wastewater was applied to the 10 m grassed portion of the buffers. Transects of shallow groundwater wells starting at the grass-forest interface and running downslope were used to monitor water quality N. The study showed mixed results concerning N assimilation by the buffers. Upslope land use changes by the producer during the study added significant N inputs to one set of buffers, and they were unable to assimilate sufficient N from both these inputs and the wastewater to protect shallow groundwater quality. In contrast, almost all samplings of shallow groundwater under the buffers receiving N only from the overland flow applied swine lagoon effluent showed nitrate (NO 3 −N) concentrations 20 and 30 m downslope to be lower than 10 mg L −1 (drinking water standard). On these buffers, NO 3 −N concentrations in shallow groundwater were near background levels five years after wastewater application commenced. The study indicated that the ratio of buffer area width to wastewater application area width on the landscape should be at least 1:1, and that buffers for protection of water quality should be continuous on the landscape. It was concluded from the study that buffers can be used at the farm scale to assimilate N from applied wastewater when they are sufficiently wide relative to waste application area, rate, and other N sources at the farm scale.

Acta horticulturae, 2004

Entomosporium leaf spot (Entomosporium mespili (DC.) Sacc.) on Indian hawthorn (Rhaphiolepis sp.)... more Entomosporium leaf spot (Entomosporium mespili (DC.) Sacc.) on Indian hawthorn (Rhaphiolepis sp.) is recognized as a damaging disease in nurseries and landscapes. Thirteen selections Indian hawthorn were established in replicated plots in Tifton, Georgia (USDA 8a) on a Tifton loamy sand and evaluated for resistance to leaf spotting and defoliation in May of 1997, 1998, and 2001. Climatic conditions were not suitable for disease development in 1999 or 2000. Ratings by selection to the disease were: 'Minor', 'Georgia Petite', Olivia TM (excellent); 'Georgia Charm' (good); Eleanor Taber TM and 'Pink Pearl'(moderate); and 'Snow White', 'Clara', Ballerina®, Bay Breeze®, Cameo®, 'Elizabeth', and 'Kathy' (unacceptable). Due to extensive disease development and defoliation unacceptable selections should not be recommended for nursery production or landscape use in the southeastern United States. Minor fire blight damage occurred only on the selection Olivia TM .

Journal of environmental horticulture, Sep 1, 1998

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.

Journal of environmental horticulture, Mar 1, 1994

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.

Horttechnology, Dec 1, 2019

<jats:p><jats:italic>Ilex crenata</jats:italic> Thunb. `Rotundifolia' split... more <jats:p><jats:italic>Ilex crenata</jats:italic> Thunb. `Rotundifolia' split-root plants were grown for 3 weeks at root-zone temperatures of 30/30, 30/34, 30/38, 30/42, 34/34, 38/38 and 42/42. The 38 C root-zone temperature treatment was the upper threshold for a number of growth and physiological parameters. A portion of the root system grown at near optimum temperatures could compensate in terms of shoot growth for part of the root system exposed to supraoptimal root-zone temperatures up to the 38 C critical threshold. Higher root-zone temperatures did not affect photosynthetic rates or root:shoot ratios, but altered photosynthate partitioning to different stem and root sinks. Although no differences were found for total <jats:sup>14</jats:sup>C partitioned to the roots, partitioning of the <jats:sup>14</jats:sup>C into soluble and insoluble fractions and the magnitude of root respiration and exudation were influenced by treatment. Heating half of a root system at 38 C increased the amount of <jats:sup>14</jats:sup>C respired from the heated side and increased the total CO<jats:sub>2</jats:sub> respired from the non-heated (30 C) half. Exposure of both root halves to 42 C resulted in membrane damage which increased the leakage of <jats:sup>14</jats:sup>C photosynthates into the medium.</jats:p>

Acta horticulturae, Oct 1, 2014

High substrate pH is a major problem for producers of container-grown plants and seedlings. The p... more High substrate pH is a major problem for producers of container-grown plants and seedlings. The primary cause of high substrate pH is irrigation water with high alkalinity. Alkalinity is defined as the capacity of water to neutralize acids. Some alkalinity in irrigation water is beneficial as it serves as a buffer to large swings in pH levels, but high alkalinity in the water often leads to micronutrient deficiencies. Alkalinity of irrigation water should be monitored for changes on a regular basis. Be sure to check with the laboratory being used to determine if they test for alkalinity, carbonates and bicarbonates, or water hardness. Guidelines and suggestions for dealing with alkalinity in irrigation waters are given.

Acta Horticulturae, 2017

The University of Georgia (UGA) Department of Horticulture is well known for its ornamental plant... more The University of Georgia (UGA) Department of Horticulture is well known for its ornamental plant breeding efforts. Beginning in the 1990s with faculty such as Will Corley, Michael Dirr, and Allan Armitage, these efforts are being continued today by John Ruter, Donglin Zhang, Matthew Chappell, and Carol Robacker. Dr. Ruter works on herbaceous and ornamental plants, including the following genera: Abelia,

Hortscience, 2015

Sustainable use of water resources is of increasing importance in container plant production as a... more Sustainable use of water resources is of increasing importance in container plant production as a result of decreasing water availability and an increasing number of laws and regulations regarding nursery runoff. Soil moisture sensor-controlled, automated irrigation can be used to irrigate when substrate volumetric water content (u) drops below a threshold, improving irrigation efficiency by applying water only as needed. We compared growth of two Gardenia jasminoides cultivars, slow-growing and challenging 'Radicans' and easier, fast-growing 'August Beauty', at various u thresholds. Our objective was to determine how irrigation can be applied more efficiently without negatively affecting plant quality, allowing for cultivar-specific guidelines. Soil moisture sensor-controlled, automated irrigation was used to maintain u thresholds of 0.20, 0.30, 0.40, or 0.50 m 3 • m L3. Growth of both cultivars was related to u threshold, and patterns of growth were similar in both Watkinsville and Tifton, GA. High mortality was observed at the 0.20-m 3 • m L3 threshold with poor root establishment resulting from the low irrigation volume. Height, width, shoot dry weight, root dry weight, and leaf size were greater for the 0.40 and 0.50 m 3 • m L3 than the 0.20 and 0.30-m 3 • m L3 u thresholds. Irrigation volume increased with increasing u thresholds for both cultivars. For 'August Beauty', cumulative irrigation volume ranged from 0.96 to 63.21 L/plant in Tifton and 1.89 to 87.9 L/plant in Watkinsville. For 'Radicans', cumulative irrigation volume ranged from 1.32 to 126 L/plant in Tifton and from 1.38 to 261 L/plant in Watkinsville. There was a large irrigation volume difference between the 0.40 and 0.50-m 3 • m L3 u thresholds with little additional growth, suggesting that the additional irrigation applied led to overirrigation and leaching. Bud and flower number of 'Radicans' were greatest for the 0.40-m 3 • m L3 u threshold, indicating that overirrigation can reduce flowering. The results of this study show that growth of the different G. jasminoides cultivars responded similarly to u threshold at both locations. Similarities in growth and differences in irrigation volume at the 0.40 and 0.50-m 3 • m L3 u thresholds show that more efficient irrigation can be used without negatively impacting growth.

Hortscience, Sep 1, 2017

Interspecific and intergeneric crosses were performed between species in the genera Baptisia and ... more Interspecific and intergeneric crosses were performed between species in the genera Baptisia and Thermopsis with the goal of creating hybrids with the best qualities of both parents. Baptisia australis (L.) R. Br. was used as both the male and female parent in intergeneric crosses. Thermopsis chinensis Benth. ex S. Moore, T. lupinoides (L.) Link, and T. villosa Fernald & B.G. Schub. were used as male and female parents in both interspecific and intergeneric crosses. Pollen was collected from B. alba (L.) Vent., B. bracteata Muhl. ex Elliott, and B. lanceolata (Walt.) Ell. and used to make interspecific and intergeneric crosses. Putative hybrids were obtained from both interspecific and intergeneric crosses. Interspecific crosses produced a higher percentage of pollinations resulting in seed set and the number of seeds per pollination than intergeneric crosses. Morphological differences between parent species and progeny were evident in putative hybrids resulting from intergeneric crosses between T. villosa and B. australis and T. villosa and B. alba. Most putative hybrids bloomed during the second year after germination. Because seedlings could be obtained from both interspecific and intergeneric crosses, hybrids within and between the genera Baptisia and Thermopsis are feasible. The Fabaceae family contains 670-750 genera and 18,000-19,000 species. Baptisia (commonly called false or wild indigo) and Thermopsis (commonly named false lupine) of the Fabaceae belong to the tribe Thermopsidae, which comprises 46 species in six genera. All species in Thermopsis and Baptisia are herbaceous; they are the only two genera in Thermopsidae that do not have woody species. Thermopsis contains 23 species and has a widespread distribution with species endemic to Asia and much of temperate North America. Although Thermopsis is considered to have originated in central Asia, T. chinensis Benth. ex S. Moore and T. fabacea (Pallas) Candole are thought to have originated in North America and migrated over the Bering Land Strait to Asia. Three Thermopsis species, T. fraxinifolia Nutt. ex M.A. Curtis, T. mollis (Michx.) M.A. Curtis ex A. Gray, and T. villosa Fernald & B.G. Schub., are native to the southeastern United States. Baptisia contains 15-17 species that are endemic to the southeastern and midwestern United States.

Journal of environmental horticulture, Mar 1, 1994

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.


Journal of environmental horticulture, Mar 1, 1992

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.

Transactions of the ASAE, 1999

A two-year study was conducted to determine the growth response of six different wetland/riparian... more A two-year study was conducted to determine the growth response of six different wetland/riparian plant species receiving swine lagoon effluent. Wastewater from the third lagoon of the University of Georgia main swine unit at Tifton, Georgia, was applied to replicates of the species Ilex cassine ('Dahoon Holly'), Cephalanthus occidentalis ('Buttonbush'), Itea virginica ('Virginia Sweetspire'), Spartina patens ('Saltmeadow Cordgrass'), Juncus effusus (Soft Rush), and Panicum hemitomon ('Maidencane'). The plants were grown in open ended steel containers recessed in the soil at a field site so that they received natural weather conditions in addition to applied wastewater. Measurements were taken periodically of plant height, plant width, biomass, leaf area, and N and P content. All six plant species responded to wastewater with increased growth, and were tolerant of the level of wastewater application. It was found that of the broad-leaved species Cephalanthus had the greatest growth response, while of the non-broad-leaved species Spartina had the greatest growth.

Horttechnology, Dec 1, 2013

Hortscience, May 1, 2023

Salvia coccinea is a valuable flowering annual that attracts hummingbirds and bees to the garden,... more Salvia coccinea is a valuable flowering annual that attracts hummingbirds and bees to the garden, but few cultivars are commercially available. There is a limited range of petal colors and no leaf variegation. This research aimed to improve the ornamental value of S. coccinea by inducing mutations with ethyl methanesulfonate (EMS). The standard, red-flowered species was selected for treatment by exposing seeds to 0%, 0.4%, 0.8%, or 1.2% EMS for 8, 12, or 24 hours. The optimal treatment rate was determined to be 1.2% EMS for 8 hours, which generated desirable mutations near the median lethal dose (LD 50). The M 1 population had a 53% germination rate and was completely morphologically uniform. By the M 2 , mutations included differences in leaf shape and flower size in addition to albina, chlorina, virescens, and chimeral chlorophyll changes. A 1% mutation rate was achieved in this breeding program with seven unstable mutations and six stable mutations. The normalized difference vegetation index (NDVI) values were measured to determine differences in chlorophyll content between lethal albina mutations, chartreuse chlorina and virescens mutations, and typical leaf color. Future work will investigate the stability and heritability of chlorophyll variegation by hybridizing these selections with coral-flowered accessions of S. coccinea.

Transactions of the ASABE, 2007

A farm-scale study was conducted from 2000 to 2004 to determine the effectiveness of grass-forest... more A farm-scale study was conducted from 2000 to 2004 to determine the effectiveness of grass-forest vegetated buffers in assimilating nitrogen (N) from overland flow application of swine lagoon effluent. The rationale for the study was that replicated buffer plot studies had shown that vegetated buffers will effectively assimilate N, but it was not known whether or not they would work at a larger scale. The study was conducted on a commercial farm near Tifton, Georgia. Wastewater was pumped from a single-stage anaerobic lagoon to vegetated buffers composed of grass and mature or newly planted pines. The buffers approximated 60 m in length by 90 m in width. The upper 10 m of each buffer was in grass, while the downslope area was in mature or newly planted pines. Six buffers were instrumented for wastewater application and water quality monitoring. Two buffers received wastewater at a 1X rate (600 kg N ha −1 year −1), two at a 3/4X rate (450 kg N ha −1 year −1), and two served as controls. The wastewater was applied to the 10 m grassed portion of the buffers. Transects of shallow groundwater wells starting at the grass-forest interface and running downslope were used to monitor water quality N. The study showed mixed results concerning N assimilation by the buffers. Upslope land use changes by the producer during the study added significant N inputs to one set of buffers, and they were unable to assimilate sufficient N from both these inputs and the wastewater to protect shallow groundwater quality. In contrast, almost all samplings of shallow groundwater under the buffers receiving N only from the overland flow applied swine lagoon effluent showed nitrate (NO 3 −N) concentrations 20 and 30 m downslope to be lower than 10 mg L −1 (drinking water standard). On these buffers, NO 3 −N concentrations in shallow groundwater were near background levels five years after wastewater application commenced. The study indicated that the ratio of buffer area width to wastewater application area width on the landscape should be at least 1:1, and that buffers for protection of water quality should be continuous on the landscape. It was concluded from the study that buffers can be used at the farm scale to assimilate N from applied wastewater when they are sufficiently wide relative to waste application area, rate, and other N sources at the farm scale.

Acta horticulturae, 2004

Entomosporium leaf spot (Entomosporium mespili (DC.) Sacc.) on Indian hawthorn (Rhaphiolepis sp.)... more Entomosporium leaf spot (Entomosporium mespili (DC.) Sacc.) on Indian hawthorn (Rhaphiolepis sp.) is recognized as a damaging disease in nurseries and landscapes. Thirteen selections Indian hawthorn were established in replicated plots in Tifton, Georgia (USDA 8a) on a Tifton loamy sand and evaluated for resistance to leaf spotting and defoliation in May of 1997, 1998, and 2001. Climatic conditions were not suitable for disease development in 1999 or 2000. Ratings by selection to the disease were: 'Minor', 'Georgia Petite', Olivia TM (excellent); 'Georgia Charm' (good); Eleanor Taber TM and 'Pink Pearl'(moderate); and 'Snow White', 'Clara', Ballerina®, Bay Breeze®, Cameo®, 'Elizabeth', and 'Kathy' (unacceptable). Due to extensive disease development and defoliation unacceptable selections should not be recommended for nursery production or landscape use in the southeastern United States. Minor fire blight damage occurred only on the selection Olivia TM .

Journal of environmental horticulture, Sep 1, 1998

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.

Journal of environmental horticulture, Mar 1, 1994

To direct, fund, promote and communicate horticultural research, which increases the quality and ... more To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned.

Horttechnology, Dec 1, 2019

<jats:p><jats:italic>Ilex crenata</jats:italic> Thunb. `Rotundifolia' split... more <jats:p><jats:italic>Ilex crenata</jats:italic> Thunb. `Rotundifolia' split-root plants were grown for 3 weeks at root-zone temperatures of 30/30, 30/34, 30/38, 30/42, 34/34, 38/38 and 42/42. The 38 C root-zone temperature treatment was the upper threshold for a number of growth and physiological parameters. A portion of the root system grown at near optimum temperatures could compensate in terms of shoot growth for part of the root system exposed to supraoptimal root-zone temperatures up to the 38 C critical threshold. Higher root-zone temperatures did not affect photosynthetic rates or root:shoot ratios, but altered photosynthate partitioning to different stem and root sinks. Although no differences were found for total <jats:sup>14</jats:sup>C partitioned to the roots, partitioning of the <jats:sup>14</jats:sup>C into soluble and insoluble fractions and the magnitude of root respiration and exudation were influenced by treatment. Heating half of a root system at 38 C increased the amount of <jats:sup>14</jats:sup>C respired from the heated side and increased the total CO<jats:sub>2</jats:sub> respired from the non-heated (30 C) half. Exposure of both root halves to 42 C resulted in membrane damage which increased the leakage of <jats:sup>14</jats:sup>C photosynthates into the medium.</jats:p>

Acta horticulturae, Oct 1, 2014

High substrate pH is a major problem for producers of container-grown plants and seedlings. The p... more High substrate pH is a major problem for producers of container-grown plants and seedlings. The primary cause of high substrate pH is irrigation water with high alkalinity. Alkalinity is defined as the capacity of water to neutralize acids. Some alkalinity in irrigation water is beneficial as it serves as a buffer to large swings in pH levels, but high alkalinity in the water often leads to micronutrient deficiencies. Alkalinity of irrigation water should be monitored for changes on a regular basis. Be sure to check with the laboratory being used to determine if they test for alkalinity, carbonates and bicarbonates, or water hardness. Guidelines and suggestions for dealing with alkalinity in irrigation waters are given.

Acta Horticulturae, 2017

The University of Georgia (UGA) Department of Horticulture is well known for its ornamental plant... more The University of Georgia (UGA) Department of Horticulture is well known for its ornamental plant breeding efforts. Beginning in the 1990s with faculty such as Will Corley, Michael Dirr, and Allan Armitage, these efforts are being continued today by John Ruter, Donglin Zhang, Matthew Chappell, and Carol Robacker. Dr. Ruter works on herbaceous and ornamental plants, including the following genera: Abelia,