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Kent D. Kobayashi

A simulation model consists of equations that represent the important relationships between components in a system, e.g., a plant or plant part. One of the purposes of simulation models is to simulate plant growth or plant growth processes to help further our understanding of plant growth and development. Simulation models are mechanistic or process based models that account for the physiological processes occurring in the system.

Model development involves several steps. We define the problem and defuse the system, its entities, their attributes, and important relationships. A conceptual model is often expressed visually in a relational diagram showing the components and their relationships. This diagram is formally expressed as a simulation model through the use of equations repenting the relationships in the system. We often make assumptions regarding the components and their relationships to simply the model or because of a lack of knowledge. Simulation models are generally written using a simulation language such as CSMP or STELLA® or with a programming language such as FORTRAN or BASIC. The model is verified through checking the appropriateness of the relationships and the integrity of the computer program. The model is then validated through seeing bow well it simulates the behavior of the system. Simulation models provide additional insights by enabling us to ask “What if” questions by changing of the conditions of the model and seeing the resulting changes in plant growth.

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Kent D. Kobayashi

How do we enhance the learning experience of graduate students in scientific writing, an essential skill in their professional development? A graduate course TPSS 711 “Scientific Writing for Graduate Students” was developed to address this need. Its objectives were to help students write, analyze, and revise parts of a scientific paper; critically evaluate their own writing and the writings of others; and become familiar with types of publications. The diverse topics included purpose of scientific writing; organizing your writing; parts of a scientific paper; data analysis and growth analysis; writing the content of a poster or oral presentation; newspaper articles and popular works; extension publications; technical writing for the general public; thesis/dissertation writing; a journal editor's perspective; and reviewing a manuscript. TPSS 711 had an enrollment of 11 TPSS master's students. Students were in their second through fifth semesters of their graduate program. A student survey showed no student had submitted a manuscript to a peer-reviewed journal, had a peer-reviewed article published, or had a newspaper, trade magazine, or popular work published. Only 9% of the students had a paper published in a conference proceedings or presented a scientific paper outside Hawaii, with only 18% having presented a paper in Hawaii. Writing assignments, in-class activities, and evaluations of the writings of others helped students gain intensive hands-on experience in scientific writing. As a course requirement, students submitted an abstract and presented a paper at our college's annual scientific symposium. Course evaluations indicated this course was important and valuable in helping enhance the students' learning experience.

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Kent D. Kobayashi

Controlling plant height is an important practice in the ornamental plant industry. Though commonly used, growth regulators are expensive, and there are concerns about environmental consequences and safety of workers. Alternative ways of controlling growth may be advantageous. The objective of this study was to determine the effects of photoselective shadecloths on the growth and flowering of `Arezzo' chrysanthemum. One-month-old potted `Arezzo' chrysanthemum plants were grown in a saranhouse in chambers built with PVC (polyvinyl chloride) pipe covered with 30% shadecloths—red, blue, gray, and black (control). The blue shadecloth was more effective in reducing plant height, with no differences among the other shadecloths. Plant canopy dimensions—greatest canopy width and average canopy width—did not show any differences among the shadecloths. The red shadecloth was more effective in hastening flowering, followed by the blue shadecloth. This was evident by flowering first occurring with the red shadecloth and initially the greatest number of buds showing color. Additionally, the red shadecloth had the highest proportion of the number of flowers to the combined number of flowers and buds showing color. Specifically, the total number of flowers was similar to the total number of buds showing color. In contrast with the other shadecloths, there was a greater number of buds showing color than the number of flowers. The most buds showing color occurred with the gray shadecloth. The three shadecloths resulted in a greater number of the combined buds showing color and flowers than the black shadecloth. In conclusion, photoselective shadecloths may provide an alternative to controlling plant height and altering the flowering pattern of potted chrysanthemums.

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Kent D. Kobayashi

The simulation programs Stella® (High Performance Systems) and Extend™ (Imagine That!) were used on Apple® Macintosh® computers in a graduate course on crop modeling to develop crop simulation models. Students developed models as part of their homework and laboratory assignments and their semester project Stella offered the advantage of building models using a relational diagram displaying state, rate, driving, and auxiliary variables. Arrows connecting the variables showed the relationships among the variables as information or material flows. Stella automatically kept track of differential equations and integration. No complicated programming was required of the students. Extend used the idea of blocks representing the different parts of a system. Lines connected the inputs and outputs to and from the different blocks. Extend was more flexible than Stella by giving the students the opportunity to do their own programming in a language similar to C. Also, with its dialog boxes, Extend more easily allowed the students to run multiple simulations answering “What if” questions. Both programs quickly enabled students to develop crop simulation models without the hindrance of extensive learning of a programming language or delving deeply into the mathematics of modeling.

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Kent D. Kobayashi

Plant nutrient management and irrigation practices are crucial in helping achieve optimal crop growth, yield, quality, and grower profitability (Mikkelsen, 2011). As the availability of suitable land for crop production decreases and the concern for adequate water increases, more efficient methods of irrigation are needed (De Pascale et al., 2011). To improve agricultural sustainability in Hawaii, growers need to rely more on locally produced amendments and less on out-of-state inputs in their fertility program. Common organic amendments that can be used in conventional and organic vegetable production directly affect soil characteristics, nutrition, and biological properties, and

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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.

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Kent D. Kobayashi

Mobile devices such as smartphones and tablet computers are increasingly being used to supplement the use of laptops and desktop computers. Their small size makes them portable and convenient to use. These devices are providing horticulturists with new tools for their work. Mobile applications (apps) are software applications that run on smartphones and tablet computers. They can be easily downloaded to a smartphone or tablet computer. There are hundreds of thousands of apps available, covering a wide range of topics. Many apps are free, whereas others have a cost. Horticulture-related apps for research, extension, teaching, and industry are available. These apps deal with diverse topics such as food safety, geographic information systems, hydroponics, scouting for insects, turfgrass management and weeds, plant growth regulator (PGR) calculations, conservation trees (trees suitable and recommended for conservation plantings), landscape design, plant and tree identification, crop protection product information, and industry trade publications. This article gives an overview of some of the horticulture-related apps that are available. Are there horticulture-related mobile apps for me? Yes!

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Kent D. Kobayashi

Student engagement in the classroom is critical for effective learning. To enhance student engagement, several teaching approaches can be used, including a flipped classroom approach and virtual field trips. The flipped classroom approach was used in an undergraduate tropical production systems course in which students viewed lecture materials outside of class, brought their smart devices to class to review materials, searched for new information on the Internet, and participated in small group discussions. In the virtual field trip assignment, each student visited a commercial farm or nursery, interviewed the owner or manager, and gave a presentation to the class about the operation of the enterprise and its sustainable practices.

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Kent D. Kobayashi*

Controlling plant height is an important practice in the ornamental plant industry. With high cost of growth regulators and concern about their environmental aspects and health of workers, alternative ways of controlling growth may be advantageous. Objective was to determine effect of photoselective shadecloth and plastic film on growth of `Barbara', `Shasta', and `Chesapeake' mums under supplemental lighting. In experiment 1, `Barbara' plants (two and four weeks old) were placed under either wide spectrum fluorescent lamps and incandescent light bulbs (control) or lights covered with photoselective shadecloth. In experiment 2, 3-week-old `Shasta' and `Chesapeake' plants were placed under lights or lights covered with photoselective plastic film. Effect of shadecloth differed with age of `Barbara' plants. For 1-month-old plants placed under lights, stem diameter, stem dry weight, and root dry weight were reduced under shadecloth compared to control. No differences were observed for plant height, pot height, leaf number, leaf area/plant, and leaf dry weight. For 2-week-old plants, leaf number, leaf area/plant, leaf dry weight, and stem dry weight were less under shadecloth than control. No effects on plant height, pot height, stem diameter, and root dry weight were observed. Plastic film reduced plant height and pot height for `Shasta' and `Chesapeake' plants and reduced stem dry weight and total plant dry weight for `Shasta'. No differences were seen for other growth measurements. This study indicated photoselective shadecloth did not control height of `Barbara' and its effect on growth was influenced by plant age. Photoselective plastic film controlled height of `Shasta' and `Chesapeake' and offers an alternative method for growth control of mum plants.

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Guofan Liu and Kent D. Kobayashi

Four turfgrasses (Z-3, Seashore Paspalum, Common Bermuda, and Tif dwarf Bermuda) were grown outdoors in pots under different shade conditions (0%, 30%, and 50% shade) from August to December 1995. Dry weight of clippings taken every two weeks was determined. Turfgrass growth in the three shade treatments were significantly different, and the growth of the turfgrasses were highly significantly different. In the 0% and 30% shade treatments, Common Bermuda and Seashore Paspalum grew similarly, and their dry weights were significantly greater than those of Z-3 and Tif dwarf Bermuda. However, under 50% shade, only Seashore Paspalum grew significantly greater than the others. Comparing growth among the shade treatments for each turfgrass, we found no significantly differences. Only Common Bermuda grew significantly less under 50% shade than under 0% and 30% shade. Common Bermuda is good for golf courses because of its fast growth and attractiveness. Seashore Paspalum can be used for home lawns because of its vigorous growth and shade tolerance. Z-3 turfgrass, an attractive new variety for home lawns, despite its slow growth, is tolerant of different shade conditions.