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Alvan Gaus and Matthew Rogoyski

A set of 3 experiments was conducted to determine if cellulose fibers (CF) could reduce the incidence of sunburn injury in `Paulared' apples. Sunburn injury was artificially increased in these experiments by fruit manipulation and removal of shading vegetative growth to expose apples to at least 4 hours of direct sunlight. The 4 treatments applied included an unsprayed control, a commercial binding agent (CBA), a 1% corn starch (CS) colloidal suspension, and a 3% CF suspension that contains CBA and CS. No differences between treatments were found in the first experiment. The CF suspension concentration was increased to 9% for the second experiment. This resulted in uneven CF distribution on the fruit surface and no significant differences between treatments. The third experiment was designed to more precisely determine sunburn symptom expression by delineating the manipulated fruit surface area directly exposed to sunlight prior to treatment. The resulting percent of area that showed a white (bleached) sunburn symptom was significantly less for the apple fruit treated with CF than CBA alone.

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Alvan Gaus and Matthew Rogoyski

The main objective of this research was to compare the growth responses of l-year-old, vertical, apple shoots to bending with a simple hand-tool (HT) or bending with the commercially available Branch Bender® (BB). Single, vigorous, vertical shoots of `Red Chief Delicious (RCD), `Valnur' Jonathan (VJ), and Granny Smith were either bent with the BB or were bent by spirally wrapping the shoot around a 2.5 cm diameter plastic-rod, HT 2 times. Each variety had nine single-tree blocks with a control, BB, and HT as treatments. Measurements were taken on the number of clusters formed, length of subsequent terminal growth, number of shoots and spurs formed, and shoot cross-sectional area. No differences were found in RCD between the BB and the HT on all parameters; however, terminal growth was less with the BB than the control. With VJ, first year shoot cross-sectional area for the BB was less than for the HT. Cluster formation on both 1 and 2-year-old wood was greater with the BB than the control but not with the HT. No differences were found with Granny Smith.

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George M. Greene II and Alvan G. Gaus

The influence of rootstocks on the growth and productivity of `Starkspur Supreme Pagnelli Delicious' was determined in an NC-140 experiment started in 1984. The planting was supplemental to the main experiment and it contained Ottawa (Ott) 3, M.20, and Arnold Lynd (AL) 800, but did not contain Budagovsky (Bud) 490, Bud 9, Antonovka 313, or C6. Trees that apparently would not stand were given support. Data on tree size and yield were collected every year. As expected, many characteristics were strongly influenced by rootstock. Yield efficiency calculated as the total fruit weight per square cm of trunk cross-sectional area was used as a measure of production efficiency. In 1989, efficient producers of fruit (all in decreasing order) were Poland (P) 2, EMLA.26, P 16, and Michigan Apple Clone (MAC) 39. Intermediate in productivity were M.20, Cornell-Geneva (CG) 10, Pl, and AL 800. A lower efficiency group of rootstocks were EMLA.7, Ott 3, MAC 1, Seedling, M.4, P 18, and CG 24. `Golden Delicious' and `McIntosh' on EMLA.26, used as pollinizers, were ranked second and third in yield efficiency.

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Alvan Gaus, Cecil Stushnoff, and Ann McSay

Proper identification of apple rootstocks has always been a problem for nurseries and fruit growers. There needs to be a rapid, inexpensive, and repeatable protocol for identification of apple rootstocks. Fourier transform infrared spectroscopy (FTIR), an analytical chemical technique based on infrared laser characterization of molecular bonding energies for biochemical compounds, such as proteins, may provide an answer. Several rootstocks from the 1984 NC-140 apple rootstock trial were compared. Using a BioRad research spectrometer, spectra derived from 1000 scans per freeze dried sample were used to compare the rootstocks. Using Hit Quality Indices (HQI) generated by Lab Calc software, the rootstocks M.7 EMLA, B.9, and a seedling rootstock were compared with themselves, and each of the other two samples. A perfect match gives a HQI of zero. It was found that root cortex tissue could be used to separate these rootstocks from each other, but root xylem tissue was a poor tissue to use for identification.

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Alvan G. Gaus and George M. Greene II

Water stress in mature `Redhaven' / Lovell peach [Prunus persica (L.) Batsch] trees was imposed, during the 1988 growing season. Trickle irrigation was reduced from 100% to 25% of a calculated weekly evaporation amount on 22 June, 11 July, and 8 and 27 Aug. Trees were isolated from rainfall by tents under the canopy and from horizontal water movement between root systems on 4 sides to a depth of 0.5 m by a water-proof barrier. Canopy to air temperature differentials monitored throughout the growing season were developed into 3 stress indexes: crop water stress index (CWSI); cumulative crop water stress index (CCWSI); and postharvest cumulative crop water stress index (PCCWSI). CWSI values varied from 0 to 0.6, while both CCWSI and PCCWSI increased through late Sept. Mean PCCWSI of the 22 June 25% treatment increased at a greater rate than the other treatments. Significant linear regressions were found with some of the indexes and net photosynthesis or stomatal conductance; however, the r-square values were low. In general, no linear relationships were found between either CCWSI of PCCWSI and the Index of Injury for cold hardiness.

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George M. Greene, Alvan G. Gaus, and Laura J. Lehman

A grant from the Pa. Dept. of Agriculture has allowed Penn State University to increase postharvest physiology research of fruit, vegetables, and mushrooms. One part of this program is a CA storage research facility described herein. An insulated pole barn (26m × 18m with 5m ceilings) houses the facility. Three coolers (6m × 7m with 10cm insulation) provide environmental control for the CA systems (-2 to 10C ±0.5C). A laboratory within the building (6m × 7m × 3m) provides space for product evaluation and for CA control equipment. A total of 239 steel drums (208-liter), fitted with 28 cm round plexiglass windows, are the CA chambers. Gas pumps provide flow to: each chamber, the gas analysis system, and the CO2 scrubbing system. A David Bishop Instruments Oxystat 2, analyzes O2 and CO2 and provides control signals. High CO2 can be removed either by lime scrubbing or by flushing with gases containing N2 and the desired O2 level. Several large experiments involving 7.8 MT of apples were started and preliminary results will be presented.

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Matthew Rogoyski, Alvan Gaus, Byron McNew, Israel Broner, and Thomas Mourney

A simulator of a control system for evaporative cooling of crop canopies was developed. This development, prior to implementation of an irrigation/cooling system, allowed for experimentation before committing resources to the field system. The project provided insight into problems of modeling interaction between biological, mechanical, and digital systems and demonstrated how specialists from diverse areas can solve these problems. The object orientation methodology and the C++ programming language were tools for development of this simulator. A communication mechanism was devised to facilitate interactions between software entities representing both concrete and abstract objects corresponding to the problem domain. The object-oriented approach to the system development allowed for better communication between team members, irrespective of their background in software engineering. The modular and polymorphic nature of the object-oriented code made it possible to plan for code reuse in future projects. Simulator development using the object-oriented paradigm was found to be preferable over the procedural model used by team members in other projects in the past.

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Matthew Rogoyski, Alvan Gaus, Thomas Mourey, Israel Broner, and Jeffrey Lakey

A novel way to capture long-standing agricultural experience and knowledge in the form of generative patterns is proposed. These patterns can be thought of as solution paradigm where the solutions are the essence of the patterns. A pattern does not provide a concrete solution to a problem but can be considered of as a worldview of the problem or a solution space. A pattern initiates and generates human cognitive behaviors that indirectly facilitate, elucidate, and solve a problem. An application of generative patterns to production agriculture is proposed. An individual pattern, as described here, associates a problem, its context, the forces affecting it, and a solution. A pattern recurring in production agriculture, the socalled uniformity pattern, is presented, and its horticultural example is discussed.

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Matthew Rogoyski, Alvan Gaus, Israel Broner, and Thomas Mourey

An evaporative cooling system for apple trees was implemented. The system is automated to conserve irrigation water. The automation is based on the digital, integrated thermometer and thermostat chip embedded in the artificial fruit. The thermometer–thermostat chip drives a solid state relay. The relay controls a solenoid operated valve. A typical duty cycle consisted of 1 to 2 minutes of wetting (water on) to 4 to 10 minutes drying (water off). Differences in the length of duty cycles between individual chips were observed. The reliability of the system was adequate. The waterproofing of the system's electrical components was its weak point. Irrigation water deposits accumulated on the apple fruit surface during the growing season were readily removable with a simulated brush technique.