Judith A. Abbott and David R. Massie
Firmness is a critical quality characteristic in kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson] marketing. The industry seeks a nondestructive method for firmness sorting. We measured sonic vibrational responses of 149 kiwifruit over the range 0 to 2000 Hz and compared them with Magness-Taylor (MT) penetrometer values. Sonic resonant frequencies and mass were combined to calculate a sonic stiffness coefficient. Coefficients of determination (r2) for sonic stiffness coefficients versus MT slope and log of MT maximum force were 0.88 and 0.86, respectively. Sonic stiffness coefficients provided good to excellent classification of kiwifruit into two or three firmness categories based on MT maximum force values. A combination of amplitudes at several specific sonic frequencies selected by stepwise discriminant analysis or regression tree analysis also provided successful sorting algorithms. Identification of soft kiwifruit was 89% to 96% accurate and of firm kiwifruit 83% to 91%. These conclusions are based on a rather small sampling of kiwifruit of a single source and size, but the results clearly indicate the potential of a nondestructive firmness measurement based on sonic frequency vibrations.
Judith A. Abbott, A. Raymond Miller, and T. Austin Campbell
Mechanical stress received by pickling cucumbers (Cucumis sativus L.) during harvest can cause physiological degeneration of the placental tissues, rendering the cucumbers unsuitable for use in some pickled products. Cucumbers were subjected to controlled stresses by dropping and rolling under weights to induce such degeneration. Following storage at various temperatures for O, 24, and 48 hours, refreshed delayed light emission from chlorophyll (RDLE) was measured and transmission electron micrographs of chloroplasts were made. Mechanical stress rapidly suppressed RDLE and induced accumulation of starch granules within the chloroplasts. Rolling usually had a greater effect on RDLE than did dropping. After 48 hours, RDLE suppression persisted; starch granules were no longer evident in chloroplasts from mechanically stressed fruit, but very electron-dense inclusions had developed in the chloroplasts. Storage temperatures affected RDLE levels but had minimal interaction with stress responses. Cucumber lots subjected to excessive mechanical stress likely could be detected using RDLE measurement.
, students were exposed to methods and instrumentation that most undergraduates in our program do not experience. Moreover, students were given exposure to the basic practice of pollen quality assessment, a practice critical to determining pollen fertility
J.M. Clements, W.P. Cowgill Jr., and J. F. Costante
An accurate and efficient system for measuring and recording fruit quality data was developed. Utilizing this procedure and custom made instrumentation. two individuals can efficiently collect, measure and record the following data: apple fruit size (weight and diameter), % red skin color, length/diameter ratio, flesh firmness, soluble solids. seed count. and starch-iodine index at a rate exceeding 60 fruit/hour. If starch iodine and seed counts are eliminated, 100 fruit/hour rates can he achieved. One individual can test 40-50 fruit/hour.
Testing equipment/materials consist of a mechanical weight scale; custom made length/diameter ratio gauge; custom made flesh firmness instrumentation; refractometer; starch-iodine solution and pie pans; and an electronic data-logger. All data is manually entered. The use of custom equipment constructed from readily available parts combined with the UVM Fruit Testing Protocol, has greatly enhanced the speed and accuracy of testing, measuring and quantifying apple fruit quality data.
Katharine B. Perry, Rodger R. Getz, and H. Ray Kimsey Jr.
Access to weather information for planning and implementing horticultural practices is an important component of the production system for growers. Advances in meteorological instrumentation, data acquisition and storage, and communications technologies have improved greatly the potential for applying sophisticated weather information into daily on-farm decisionmaking. The North Carolina Agricultural Weather Program seeks to provide weather information to the horticultural interests of the state. It has developed over the past 13 years. Recently, budget reductions near 50% and the loss of two-thirds of the extension full-time equivalents have necessitated significant changes. Through regional cooperation and the use of electronic communications technology, the program has sustained these negative impacts and emerged as an improved program. This paper describes the evolution of a state agricultural weather program into what is now a regional cooperative project to provide the weather information horticultural producers require.
Judith A. Abbott
A rapid nondestructive method for measuring apple texture using sonic vibrational characteristics of intact apples was tested on freshly harvested `Delicious' apples from major U.S. production areas. Sonic transmission spectra and Magness-Taylor (MT) firmness were measured on whole apples and compression measurements were made on excised tissue. Two experienced Agricultural Marketing Service apple inspectors assessed each apple and assigned a ripeness score according to U.S. Dept. of Agriculture grades and standards inspection procedures (based primarily on texture). Sonic functions correlated significantly with ripeness scores, MT firmness, and forces to rupture or crush the tissue in compression. Ripeness scores were more closely correlated with the destructive firmness measurements than with sonic functions. However, sonic measurement has the advantage of being nondestructive, whereas MT and tissue compression are inherently destructive. Further research is needed to modify the Instrumentation and Sensing Laboratory`s sonic technique to improve the prediction of apple firmness before it can be adapted for on-line sorting.
R.C. Ebel, P.A. Carter, W.A. Dozier, D.A. Findley, M.L. Nesbitt, B.R. Hockema, and J.L. Sibley
Agricultural Experiment Station. We thank Charles Meadows and Research Instrumentation in the College of Agriculture for construction of the computer-controlled freezing chamber.
Stanislav V. Magnitskiy, Claudio C. Pasian, Mark A. Bennett, and James D. Metzger
plants, Dr. Kari Green-Church and Mrs. Nan Kleinholz at the Chemical Instrumentation Center, The Ohio State University, for help with mass spectrometry analysis of paclobutrazol residue in plant samples, and Mr. Bert Bishop for assistance in data analysis.
Kent D. Kobayashi*
How do we enhance students' learning experience and help them be aware of current and emerging technology used in horticulture? An undergraduate course on “Computer Applications, High Technology, and Robotics in Agriculture” was developed to address these needs. Its objectives were to familiarize students with the ways computers, high technology, and robotics are used in agriculture and to teach students how to design, build, and run a robot. The diverse topics included computer models and simulation, biosensors and instrumentation, graphical tracking and computer scheduling, new methods in plant ecology, automation and robotics, Web-based distance diagnostic and recommendation system, GIS and geospatial analysis, and greenhouse environmental control. An individual speaker presented one topic each week with students also visiting some speaker's labs. The students did active, hands on learning through assignments on computer simulations (STELLA simulation language) and graphical tracking (UNH FloraTrack software). They also built, programmed, and ran robots using Lego Mindstorms robotic kits. The course was evaluated using the Univ.'s CAFE system. There were also open-ended questions for student input. On a scale of 1 (strongly disagree) to 5 (strongly agree), mean scores of the 20 CAFE questions ranged from 3.71 to 4.75 with an overall mean of 4.22. When comparisons to other TPSS courses were possible, this course had a higher mean score for four out of seven questions. Course evaluations indicated this special topics course was important and valuable in helping enhance the students' learning experience.