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John C. Majsztrik and John D. Lea-Cox

A BRIEF HISTORY OF CHESAPEAKE BAY RESTORATION EFFORTS For almost 30 years, the Chesapeake Bay has been targeted for water quality improvements with the goal of removing the Bay and its tributaries from the Environmental Protection Agency (EPA) 303(d

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Adam F. Newby, James E. Altland, Daniel K. Struve, Claudio C. Pasian, Peter P. Ling, Pablo S. Jourdan, J. Raymond Kessler, and Mark Carpenter

Nutrient leaching and runoff due to excessive irrigation have detrimental environmental impacts, and emerging regulations require growers to minimize these impacts ( Beeson et al., 2004 ; Majsztrik et al., 2011 ). Because of limited container size

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Huifei Shen, Bing Zhao, Jingjing Xu, Xizi Zheng, and Wenmei Huang

of enzyme that oxidized micromoles of guaiacol radical per minute. Statistical analysis. The data analysis was performed using statistical software (SPSS version 22.0; IBM Corp., Armonk, NY), and Duncan’s multiple range test was used to compare

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Steven H. Schwartzkopf

The use of computerized environmental control systems for greenhouses and plant growth chambers is increasing in frequency. Computerized systems provide the potential for more accurate environmental control, while at the same time allowing changes to be made more easily than with hard-wired mechanical control systems. The ease of changing allows switching sensor types, relocating sensors and resetting control parameters without significantly affecting the overall system design. Another advantage of computerized control systems is that they provide a method for recording environmental data as they simultaneously implement their programmed control algorithms. This data can subsequently be transferred to other computers for further processing and analysis. Computerized controls also support the possibility of implementing environmental control based on either mathematical models which simulate plant growth, or on actual monitored plant performance data such as nutrient uptake or leaf temperature. This paper discusses in detail these and other advantages of using computerized environmental control systems, as well as describing the problems and disadvantages associated with their implementation and use.

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L. León, L.M. Martín, and L. Rallo

Fatty acid composition has been studied in seedlings from a diallel cross (nine families) among `Arbequina', `Frantoio', and `Picual' olive (Olea europaea L.). Variance among samples within genotype, genetic and environmental (yearly) variances, and year-to-year consistency of data were estimated. A correlation analysis of the standardized data for fatty acid composition between first and second year data was also carried out to select the most interesting genotypes as early as possible. The results showed that fatty acid composition exhibit significant differences between genotypes and years. The variance component attributable to differences between genotypes represented >60% of total variance for all the fatty acids evaluated. High correlation coefficients between the first and second year data were found for oleic and linoleic acid percentage; these correlations were slightly poorer for the other fatty acids analyzed. These results may be useful for improving the efficiency of olive breeding programs in first-stage selection on whole progeny populations.

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Dawn M. Alleman, Robert W. Langhans, and Ellen Wells

Ability to predict daily leachate volumes in greenhouse production enables strategic planning for the remediation of waste water. A case study greenhouse site (1620ft2) on Cornell campus was chosen because of the tile drainage system installed beneath. Roses `Sonya', `Royalty', and `Mary DeVor' were grown in 1170ft2 of bench and fertigated at bench level with automated spray nozzles. Data collection occurred over a 1.5 year period. Factors considered in modeling included: leaf area, irrigation and leachate volumes, and atmospheric / greenhouse environmental conditions (solar radiation, precipitation, temperature). Separate day and night models resulted, the night model included a condensation factor. Correlation existed between environmental factors, irrigation volume and leachate volume in the day model. In the night model a relationship between environmental factors and condensation was evident.

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L.B. McCarty, J.R. Haun, and L.C. Miller

1 Assistant Professor of Environmental Horticulture, 1545 Fifield Hall, Univ. of Florida, Gainesville, FL 32611. 2 Professor Emeritus. 3 Professor. Technical contribution no. 2556 of the South Carolina Agricultural Experiment Station

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R.L. Green, S.I. Sifers, C.E. Atkins, and J.B. Beard

We compared evapotranspiration (ET) rates for 11 Zoysia genotypes, encompassing two species and their hybrid, maintained at nonlimiting soil moisture under field conditions and in an environmental chamber of high evaporative potential. ET rate relationships to leaf area [leaf extension rate (LER)], canopy resistance [shoot density (SHD)], and internal resistance [abaxial (AB) and adaxial (AD) leaf blade stomatal densities] characteristics were determined. Three-year ET rate means were not significantly different among genotypes in the field study, but ET rates among genotypes differed significantly under the higher evaporative potential of an environmental-chamber study. ET rate was not significantly correlated with LER for either the data from the field or the chamber. ET rates of both types of tests also were not significantly correlated with SHD or AB or AD leaf blade stomatal density. Data from field and environmental-chamber research suggest that differences of individual morphological traits among the 11 zoysiagrasses do not influence the ET rate when measured from minilysimeters maintained at nonlimiting soil moisture.

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Dennis Decoteau, Jonathan Ferdinand, Jim Savage, Dick Stevenson, and Donald Davis

Penn State's Air Quality Learning and Demonstration Center was completed and open to the public in 2003. The facility houses the State College air monitors for the Department of Environmental Protection and contains self-guided walkways through gardens of air pollution sensitive plants, innovative techniques for demonstrating the effects of air pollutants on plants, displays of recent research findings, industry-supported displays of pollution abatement technologies, and a teaching pavilion. One of our outreach projects, funded by the US EPA and the PA Department of Environmental Protections, is to provide enhanced teacher training on air pollution impacts on the regional and specific vegetation through an in-service training for local science school teachers utilizing on-site and archived data on weather conditions and plant injury symptom development. The picture archive began to be developed during Summer 2005 using video cameras that are permanently mounted for the growing season inside the open-top chambers and focused on a plant (and a specific leaf or set of leaves). Once the teachers are trained to utilize these data sets appropriately, they will be able to access the data during the school year through the Learning Center website and conduct the same analysis with their students in their classroom during the school year. This use of archival information is important because the school year does not coincide with optimum times for observing air pollution symptoms on vigorously growing field-grown plants in Pennsylvania (which is best during the summer).

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John F. Willcutts, Allen R. Overman, George J. Hochmuth, Daniel J. Cantliffe, and Puffy Soundy

Modern fertilization recommendations must optimize crop yield and quality and minimize chances of negative environmental effects due to overfertilization. Data from fertilizer studies can be fitted to several mathematical models to help determine optimum fertilizer rates, but resulting recommendations can vary depending on the model chosen. In this research, lettuce (Lactuca sativa L.) was used as a case study vegetable crop to compare models for estimating fertilizer N requirements. Greenhouse studies were conducted with `South Bay' and `Sierra' cultivars of crisphead lettuce to measure yield response to applied N. Individual plants were grown in pots and received six rates of N (0.0, 0.2,0.4,0.6,0.8, and 1.0 g/plant) as ammonium nitrate in split applications. Data for plant fresh mass and N uptake were recorded. The logistic model described the data for both cultivars quite well, with correlation coefficients of 0.98 and above. The logistic model was also applied to field data for average head mass of `South Bay' lettuce following application of N at 0,56,112,168,224, and 280 kg·ha-1. Logistic, linear-plateau, and quadratic models were compared for the field data. Coefficients for the linear-plateau model were derived from the logistic model. All three models for lettuce production were compared graphically and analytically. The model coefficients were then used to make improved estimates of fertilizer recommendations for field production of lettuce.