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MAT-SLF-Matprogr.:Prosj.fullfin.av SLF

An energy dynamic Norwegian greenhouse industry (VeksthusDynamikk)

Awarded: NOK 10.5 mill.

Main goal: An energy efficient and environmentally friendly greenhouse production Results: - Optimal CO2-monitoring gives good economy. Up to 100 % increase was documented in photosynthesis/growth by high CO2-level (800-1200 ppm) at high temperature (about 30 ?C) for 6 hours in the midle of the day. With a 20 hour day length, this would give a 30 % growth increase per day. An investment to make this work will be paid back in 4 years. - Heat storage, dehumidification/cooling. With an investment of NOK 500.000 for a greenhouse area of 1000 m2, approximately 200.000 KWh/year may be harvested. If this energy is used to heat the greenhouse, the investment will be paid back in 6 years. By using the same technical solution and keeping a high CO2 level (reduced ventilation), the investment can be paid back in 2.5 years. - In greenhouse grown cucumbers, there is some use of fungicides. The project has done research that shows the possibility to treat powdery mildew by ultraviolet light (UV-B) during the night and taken part in developing equipment for UV treatments under practical conditions in greenhouses. By an investment of NOK 250.000 in a UV-B robot, this can have a capacity to treat 5000 m2. These costs will be less and the capacity extended in normal commercial use. The investment in the UV-method will be paid back in 3.5 years. - LED vs. SON/T. LED-lamps give a 20 % higher yield in µmol s-1 m-2 per Watt compared to SON/T, however, experiments comparing LED with SON/T gave the same growth per KWh, because of the additional heat provided by SON/T. With this background, the LED-installation will cost NOK 376.000 more per 1000 m2 and year than SON/T. - Low night temperature has little effect on the photosynthesis the next day. It is important to keep an optimal temperature throughout the day and night, to control the development rate of the plants. - LEDs gave more compact plants than SON/T or natural light. This means that LED combined with UV-B may fully or partly replace chemical growth retardants. - Response to relative air humidity and hormone regulation by herbaceous plants is different from woody plants. Abscisic acid (ABA) seems to be less important in stomata regulation in tomato and cucumber than in roses. - For tomato, ethylene is involved in regulation of stomata functions, and high relative air humidity increase the production and sensitivity for ethylene. Because of that, stomata will remain open for longer at high humidity. - Conditions under production (light quality, temperature, relative air humidity, etc.) influence transpiration and postharvest quality. Blue light gives a signal that influence regulation of stomata and can be used to increase the transpiration and ensure optimal nutrient uptake under high air humidity in tomato and cucumber. Blue light also influences the level of ABA and the ABA-metabolism and subsequently the drought tolerance after harvest. - Powdery mildew (PM) is influenced of day length and light quality. o A 20 hour or longer day inhibits development of PM. o Red light inhibits development of PM, while dark red promotes it. - Wavelengths between 250 and 280 nm were equally effective in killing PM. The effect was dose dependent between 290 and 310 nm and there was no effect above 310 nm. Plants are more tolerant for wavelengths in the area of 270-300 nm, which would be the best wavelengths to use in commercial treatment of PM. - Optimal dose and interval for use of UV-B to control PM of aster, rosemary, strawberry and tomato: As long as the total UV-dose was equal, there was no difference if treating the plants three times a day, once a day or every third day. - Attacks of powdery mildew in tomato was low if the proportion between reed and blue light was 75:25 or 50:50. In addition, a 50:50 ratio reduced the plant height without reducing the leaf area compared to a higher red light ratio. - In cooperation with other projects, research has started in Norway and USA to take the UV-technology into commercial production. Through PhD work at NMBU and Cornell University, we have started to achieve a better understanding of the basic genetic, biochemical and physiological processes in powdery mildews influenced by UV and light. - Dissemination. The number of articles published in international scientific journals with referee and in trade journals/oral presentations for the industry is 38 and 130, respectively. Researchers and advisors working in the project gave oral presentations at Gartner 2016, the conference organized by the Norwegian growers association for the horticultural industry. Those presentations summed up the results from the four years of the project during a 1-day seminar. Furthermore, the project organized two after-education courses with excellent participation from the greenhouse industry. One of the courses gave study points at NMBU. The project has had two seminars in cooperation with Wageningen University.

An energy dynamic Norwegian greenhouse industry (VeksthusDynamikk) Energy costs in Norwegian greenhouses amount to 25 to 40% of total costs, and it is thus a major goal for the industry to reduce energy costs, but also to become less dependent on fossil f uels. Temperature control where the temperature within a certain range follows the irradiance level may be an efficient means to reduce energy consumption. High light use efficiency in plants depends on the maintenance of a high CO2 level, and recent resu lts indicate that large temperature fluctuation may reduce this effect. We want to clarify if this is a general effect in greenhouse plants. Ventilation due to high air humidity accounts for up to 40% of the energy costs in greenhouses, and therefore we w ant to remove humidity without ventilation by condensation, using active cooling by a heat pump in a so called semi-closed greenhouse. The condensation heat will be stored in a buffer tank or used directly for heating in the greenhouse. Due to inefficient stomata closure at high humidity, night transpiration of the canopy might strongly increase the need for ventilation. We aim to improve the stomata functionality by humidity control and light quality using light emitting diodes (LED s). LEDs are anticipa ted to become superior in energy efficiency to the commonly used high pressure sodium lamps, and thus there is a great potential to improve productivity and save energy. Powdery mildews are the most important diseases in greenhouse crops, and LEDs will be a core technology in developing substitutes for chemicals controlling the diseases. Furthermore, LEDs will also be tested as possible substitutes for chemical growth regulators. Before implementing new technology derived from the project, thorough analys is of energy consumption and costs will be carried out. All work packages involve industry and international research collaboration, and our research results will be brought into educational and industry programs.

Funding scheme:

MAT-SLF-Matprogr.:Prosj.fullfin.av SLF