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Jerry M. Parsons, Tim D. Davis, Steven W. George, and Wayne A. Mackay

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John J. Sloan, Wayne A. Mackay, Phil Colbaugh, Steve W. George, and Sam Feagley

Excessive soil moisture in clay soils can cause poor aeration and adversely affect plant growth. Small [1 to 3 mm (0.039 to 0.118 inches)] and large [3 to 6 mm (0.118 to 0.354 inches)] diameter expanded shales (ExSh), quartz sand, sphagnum peatmoss (SPM), and cottonseed hulls (CH) were evaluated as soil amendments for Austin silty clay soil. A 3-inch (7.6-cm) layer of each amendment was incorporated to a depth of 6 inches (15.2 cm), resulting in a 1:1 mixture by volume. Pansies (Viola × wittrockiana `Crown Azure Blue') were grown from December to June, followed by scaevola (Scaevola aemula `New Wonder') from June to November for two growing seasons. Foliage quality and extent of flowering were evaluated biweekly. Pansy root weights and above-ground biomass were quantified at the end of each growing season. None of the amendments significantly affected pansy foliage quality or the number of blooms per plant. Small diameter ExSh and SPM decreased pansy nitrogen content the first year after application, but not the second. During the first growing season, when soils were frequently saturated due to excessive rainfall, pansy root weights were significantly higher in soils amended with the small and large diameter ExSh. Large diameter ExSh treatments significantly increased the survival rate of transplanted scaevola plants and also the quality of foliage and percent blossom coverage during both growing seasons. Cottonseed hulls also increased scaevola survival for both growing seasons, but did not consistently improve scaevola foliage quality or bloom coverage. Of the five amendments tested, large diameter ExSh consistently improved overall plant performance more than the other amendments.

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Wayne A. Mackay, Steve George, Jerry M. Parsons, Greg Grant, Tim D. Davis, and Larry Stein

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Wayne A. Mackay, Steve George, Tim Davis, Mike Arnold, Dan Lineberger, Jerry Parsons, and Larry Stein

The Coordinated Educational Marketing Assistance Program (CEMAP) is one of the oldest marketing assistance programs for ornamentals in the United States. The goal of this program is to identify outstanding plants for Texas and to provide support for the nursery industry, thereby making plants with superior performance available to the people of Texas. The CEMAP program is a cooperative effort between the Texas nursery industry and Texas A&M Univ. The CEMAP Executive Board has eight individuals representing extension, research, and teaching plus two administrative liasions and the Industry Advisory Board has ≈50 members from all segments of the ornamentals industry in Texas. Funding for the CEMAP program comes from direct industry support and from the public through the sale of plant tags or other promotional materials which bear the Texas Superstars logo. The logo is trademarked and licensed to printing companies who handle the administration of royalties to the program. The Executive Board makes the final decision about which plants are designated Texas Superstars. Promotional support for the plants is provided by CEMAP through point of purchase materials and publicity through print, radio, and television. In addition, the Texas Nursery and Landscape Association in cooperation with the Texas Department of Agriculture are conducting a publicity campaign to inform the public about Texas Superstars.

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Francisco Molinar Jr., Wayne A. Mackay, Marisa M. Wall, and Manuel Cardenas

Experiments were conducted to develop a clonal propagation system for agarita (Berberis trifoliata Moric.). Actively growing agarita shoots were collected from a mature plant at the Texas A&M Univ. Research and Extension Center in El Paso and successfully established on a basal medium consisting of woody plant medium (WPM) salts and Murashige and Skoog vitamins, sucrose at 30 g·L–1, and 0.8% Phytagar supplemented with 11.1 μm BA. Cytokinins (benzyladenine, kinetin, and thidiazuron), subculture period, and age of cultures were tested. The optimal shoot proliferation conditions were WPM basal medium supplemented with 5.5 μm BA and a subculture period of 4 weeks. Culture age did not affect shoot proliferation but did affect rooting. Preliminary experiments with 1.0 μm NAA resulted in nearly 100% rooting of microshoots <6 months old. Shoots from 21-month-old cultures had to be placed on a cytokinin-free medium before successful rooting. On basal medium supplemented with NAA (5.4 μm), 68% of the microshoots rooted with an average of 1.2 secondary roots per microshoot. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); 1-naphthaleneacetic acid (NAA); N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ); 6-furfurlaminopurine (kinetin).

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S.M. Lutfor Rahman, Wayne A. Mackay, Eiji Nawata, Tetsuo Sakuratani, A.S.M. Mesbah Uddin, and Bruno Quebedeaux

Effects of water stress on superoxide dismutase (SOD) activities, changes in protein content, leaf water potential (Ψl) and growth were studied in drought-sensitive Kyokko (KK) and Ratan (RT), and drought-tolerant TM 0126 (TM) and VF-134-1-2 (VF) cultivars of tomato (Lycopersicon esculentum Mill.) in order to obtain fundamental information for breeding drought tolerant cultivars that may be adapted to water stress in many parts of the world. Growth of drought-tolerant TM and VF was greater than that of drought-sensitive KK and RT under water stress conditions. Leaf water potential (Ψl) decreased by water stress treatments in all the cultivars, but the reduction was much more rapid and pronounced in KK and RT than VF and TM. Ψl of stressed cultivars decreased by 30% to 40% compared to the untreated control cultivars. The initial reduction in the range of 20% to 35% was more rapid in KK and RT than TM and VF. SOD activities were increased by water stress in all cultivars. Increase of SOD activities by water stress was much more rapid and pronounced in TM and VF than in KK and RT. Leaf protein concentration was decreased by the water stress treatments in all cultivars evaluated. In KK and RT, much more rapid reductions in protein concentration were observed than in TM and VF. The regression analysis of Ψl and SOD suggest the possibility to using SOD activities as an additional screening criterion for tomato drought tolerance improvement.

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Michael A. Arnold, R. Daniel Lineberger, Tim D. Davis, Steven W. George, Wayne A. Mackay, Greg D. Grant, Jerry M. Parsons, and Larry A. Stein

Plant trialing and marketing assistance programs have become popular in recent years with several state and some regional programs emerging. Successful implementation requires considerable labor, facilities, and monetary resources for evaluation of large numbers of taxa over several years to ensure that plants are well adapted to the region of interest. Research and development funds, dedicated facilities, and cooperator commitment to trialing programs can be limiting during the early years of the programs. Involvement in plant trialing programs allows students to be exposed to plot layout planning, statistical design, plant maintenance, data collection and analysis, and professional communication of trial results. Construction of facilities for conducting plant trials, growing plants for use in trials, trial installation, and maintenance of plants all provide practical hands-on horticultural training. Replicated plant trials provide the latest information on regionally adapted taxa for inclusion in classroom instruction and publications. Plant trialing programs benefit from labor assistance, development of dedicated facilities, and the opportunity to share equipment and supplies among teaching, trialing, and student research projects.

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Wayne A. Mackay, Steve W. George, Tim D. Davis, Michael A. Arnold, R. Daniel Lineberger, Jerry M. Parsons, Larry A. Stein, and Greg G. Grant

The Coordinated Educational and Marketing Assistance Program identifies outstanding landscape plants for Texas and provides support for the nursery industry, thereby making superior plants available to Texans. CEMAP funding comes directly from industry and from consumers through the sale of plant tags bearing the Texas Superstar logo. Additionally, the Texas Nursery and Landscape Association and Texas Department of Agriculture is conducting a Texas Superstar publicity campaign. An estimated $10 million in new plant sales have been generated during the first 10 years of this program. Because plants are chosen based on their performance under minimal input conditions, Texas SuperStars greatly reduce their impact on the urban environment.

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Geoffrey C. Denny, W. Todd Watson, Leonardo Lombardini, Wayne A. Mackay, Alma R. Solis-Perez, Donita L. Bryan, and Michael A. Arnold

Seedlings from 13 open-pollinated families of Taxodium distichum (L.) L.C. Richard from the gulf coast, central and south Texas, and Mexico were grown in a nursery in College Station, Texas. Forty seedlings per family were measured on three dates during the production cycle; 99, 109, and 133 days after sowing in Spring and Summer 2004. A two-step cluster analysis based on height and trunk diameter created 3 clusters of families. Cluster 1 had a mean height of 32 cm and a mean trunk diameter of 3.3 mm. Cluster 2 had a mean height of 33 cm and a mean trunk diameter of 3.4 mm. Cluster 3 had a mean height of 43 cm and a mean trunk diameter of 4.1 mm. Although clusters 1 and 2 are statistically significantly different, practically there is little difference between the two. The families from Mexico and central Texas were all in cluster 1 or 2 and the families collected from the gulf coast were all placed in cluster 3, with the exception of a single family from Biloxi, Miss., which was placed in cluster 1. Analysis of covariance revealed that family membership and days after sowing were both highly significant, as well as an interaction between family and days, for height. Families from Mexico and central and south Texas were 10 to 15 cm shorter than the families from the gulf coast, with the exception of the single family from Biloxi, Miss. Only days and the interaction between family and days were significant for trunk diameter. A pattern similar to the cluster analysis means was seen among the families for trunk diameter in the analysis of covariance.