Light Environment Management of Tropical Crops

<p>NON-TECHNICAL SUMMARY: <br/>Light is a key environmental factor influencing crop growth and development. Two important characteristics of light are quality (spectrum) and intensity (photosynthetic active radiation). Light quality has been used to manipulate the growth and flowering of various crops including dracaena, anthurium, orchid, poinsettia, chrysanthemum, and gardenia. This project addresses controlling plant growth and development using photoselective shadecloths and plastic films. Light manipulation could be used to supplement other techniques such as artificial lighting, plant breeding, growth regulators, or greenhouse control for crop management. Artificial lighting is increasingly being used for production of vegetables in controlled environment agriculture. Vegetables typically require high light intensity, which can be supplied by high discharge lighting
such as high pressure sodium lights and metal halide lights. With their constant improvement, high output fluorescent lighting and light-emitting diodes (LEDs) are low energy, low heat alternatives. A recently developed type of lighting, light-emitting plasma, has been used with tomato, lettuce, and leafy vegetables. Light quality can be adjusted using LEDs with different effects on vegetable growth. Use of artificial lighting in controlled environments could be used to enhance growth, reduce water usage, and help improve food safety. Commercial growers will adopt shadecloth/plastic film and lighting management practices to help promote environmentally responsible agricultural and landscape management; increase marketable yields; and increase profitability and competitiveness. Surveys will be conducted over time to determine the number of growers that adopt the recommended
shadecloth/plastic film and artificial lighting practices.

<p>APPROACH: <br/>Objective 1: Framing structures built with PVC pipe and fittings will be placed on and fastened to greenhouse benches in a shadehouse. The structures will be covered with the different photoselective shadecloths, and potted plants will be placed in the structures. Irrigation will be through a drip or overhead sprinkler system. Using a randomized complete block design, five rows of greenhouse benches spanning half the width of the shadehouse will be used. Pots will range from four inches in diameter to one or two gallons, depending on the size of the plants. The composition of the potting media will depend on the plants and will include combinations of volcanic cinder, orchid bark, redwood chips, peat moss, and other appropriate component substrates. Data loggers with quantum light sensors and temperature sensors will be used to monitor photosynthetic
active radiation and air temperature. A spectroradiometer and a data logger with blue, red, and far-red light sensors will be used to measure light quality. Plant data to be taken include height, leaf number, leaf area, and flowering data. This study will also look at plastic films that convert part of the absorbed ultraviolet light into visible light or red light. Two currently available films will be used, SmartLight RL 1000 and Vibatan Photoluminescent. PVC framing structures will be built on the greenhouse benches and covered with the different 3-ml plastic films. Using a randomized complete block design, three rows of greenhouse benches spanning half the width of the shadehouse will be used. Objective 2: Three sources of artificial lighting will be compared for their effects on hydroponic vegetable growth and yield. The sources are high output fluorescent lighting; high intensity
red LEDs, blue LEDs, and a combination of red and blue LEDs; and light-emitting plasma lighting. Vegetables crops will include leafy crops such as Asian greens, specialty greens, and mache (corn salad) grown in a non-circulating hydroponic system. The nutrient solution will be the Lettuce Formula 8-15-36 with calcium nitrate and magnesium sulfate added. Data loggers with quantum light sensors and temperature sensors will be used to monitor photosynthetic active radiation and air temperature. A spectroradiometer and a data logger with blue, red, and far-red light sensors will be used to measure light quality. Plant data to be taken include plant height, canopy dimensions, chlorophyll content, pH and electrical conductivity (EC) of the nutrient solution, and dry weights of leaves, stems, and roots. The CTAHR Agricultural Diagnostic and Service Center will analyze the plant tissue and
nutrient solution. Because of the use of leafy vegetables and their short life cycle, the nutrient solution in the noncirculating hydroponic tanks will be replenished with the original nutrient solution as needed.

<p>PROGRESS: 2012/10 TO 2013/09
<p>Target Audience: <br/>Target audience was scientific peers. Efforts included delivering science-based knowledge through a scientific poster presentation at the American Society for Horticultural Science Conference. Delivered science-based knowledge through formal classroom instruction and laboratory instruction in three horticulture courses--TPSS 601, 674, and 300. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Professional development activities included presenting a scientific poster at the American Society for Horticultural Science Conference. Networked and interacted with scientific peers at the conference and became aware of similar research. Became familiar with different types of artificial lighting through visiting display booths at the conference. Mentored
two University of Hawaii at Manoa College of Engineering undergraduates on their project on light-emitting diodes (LEDs) and vegetables. As a committee member of a University of Hawaii at Manoa College TPSS Department graduate student, I mentored him on his research on LEDs and hydroponic vegetables. Mentored a University of Hawaii at Manoa TPSS Department undergraduate student on his aquaponics project on LEDs, fishes, and vegetables. Mentored the Hawaii Girl Scouts International Space Station Team on their hydroponic project with LEDs and vegetables. How have the results been disseminated to communities of interest? Results have been disseminated through a scientific poster presentation and a conference abstract at the American Society for Horticultural Science Conference. What do you plan to do during the next reporting period to accomplish the goals? Continue research and
experiments. Present research results at the American Society for Horticultural Conference in July, 2014 in Orlando, FL. Develop mobile web sites (capable of being viewed on smartphones and e-tablets) which will summarize research results and conference presentations. Purchase a portable handheld spectroradiometer with the CTAHR FY 2014 Supplemental Funding I received.

<p>PROGRESS: 2011/10/01 TO 2012/09/30
<p>OUTPUTS: <br/>Conducted and analyzed experiments. Taught about and demonstrated different artificial lighting systems to students. Wrote conference abstracts, designed a conference poster and slides for a conference oral presentation. Networked with other scientists doing research on light-emitting diodes and plants. Results have been disseminated to communities of interest through presentations at a scientific conference and through conference abstracts. New knowledge was presented at a national scientific conference and included in conference abstracts.
PARTICIPANTS: Student lab assistant worked on the project.
TARGET AUDIENCES: Commercial hydroponic vegetable growers and scientists working on artificial lighting systems used in vegetable production. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

<p>PROGRESS: 2010/10/01 TO 2011/09/30
<p>OUTPUTS: <br/>Conducted and analyzed experiments. Organized photoselective shadecloth experiments in the course TPSS 364 Horticultural Practices and hydroponics experiments in TPSS 300 Tropical Production Systems. Produced a poster "Use of Light-Emitting Diodes in Anthurium Micropropagation". Presented a paper "Use of Light-Emitting Diodes in Anthurium Micropropagation" at the American Society for Horticultural Conference in Waikoloa, Hawaii September 25-28, 2011. Also, displayed this poster "Use of Light-Emitting Diodes in Anthurium Micropropagation" at the Hawaii MIDPAC Horticultural Conference in Hilo, Hawaii July 21, 2011. Created the Micro-hydroponics website ( http://4b7r.zapd.co/ ).
PARTICIPANTS: Student help assisted on this project.
TARGET AUDIENCES: Target audiences are anthurium, orchid, and vegetable growers.
PROJECT
MODIFICATIONS: Nothing significant to report during this reporting period.

<p>PROGRESS: 2009/10/01 TO 2010/09/30
<p>OUTPUTS: <br/>Results were disseminated at a national conference and in a national conference abstract. Results were shared with students in departmental courses. Participants: PI, department collaborators, and student help worked on the project. Target audiences: Researchers, extension personnel, growers, and industry organizations. Project modifications: No major changes.
PARTICIPANTS: PI, department collaborators, and student help worked on the project.
TARGET AUDIENCES: Researchers, extension personnel, growers, and industry organizations.
PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

<p>PROGRESS: 2008/10/01 TO 2009/09/30
<p>OUTPUTS: <br/>PI planned, conducted, and analyzed experiments and results. Student help assisted. Products: techniques of using light spectrum to manipulate plant growth and development. Results were disseminated through a national conference proceedings paper, two paper presentations and abstracts at a national conference, and a national newsletter.
PARTICIPANTS: PI, department faculty collaborator, and student help worked on the project.
TARGET AUDIENCES: Scientific peers, extension personnel, and growers.
PROJECT MODIFICATIONS: Nothing significant to report.

<p>PROGRESS: 2007/10/01 TO 2008/09/30
<p>OUTPUTS: <br/>Conducted and analyzed experiments. Results were disseminated through an American Society for Plasticulture conference proceedings paper and a paper presentation at an American Society for Horticultural Science conference along with the abstract in the conference program. PARTICIPANTS: PI planned, conducted, and analyzed the experiments and results. Presented findings in a national conference proceedings paper and a paper presentation at a national scientific conference.
TARGET AUDIENCES: scientific peers and growers
PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.