The Development of a Root-zone Environmental Control System (N.RECS) and Its Application to Flower Production

Abstract

Here, we describe the current status of energy-saving techniques in greenhouse heating and countermeasures for high summer temperatures, and then introduce an outline and the performance of a newly developed New Root-zone Environmental Control System (N.RECS) and the effects of this system on flower production. Temperature control techniques used in protected horticulture include those that control the air temperature of the entire greenhouse space and those that control the local temperature of the plants. The running costs of the air temperature control techniques are expensive and the cooling capacity in the summer are inadequate for actual cultivation. Local temperature control techniques have relatively low running costs and can adequately cool plants during high temperature periods, but they are crop-specific and not versatile. Therefore, we developed a N.RECS that can heat and cool the root-zone of various plants with low running costs. N.RECS was produced by combining aluminum heat exchange panels, insulated pot trays and an airsource heat pump cold/hot water supply system. By using N.RECS, the root-zone temperature was maintained at 25°C when the air temperature was about 5°C during the winter and cooled to below 23°C when the air temperature was about 35°C during the summer. Root-zone heating of six potted flowers and cut flowers in the winter promoted growth and flowering and achieved energy savings of about 30% compared to conventional heating.When the two flower species, which are susceptible to high temperature, were grown under high temperature conditions, about half of the plants died, but root-zone cooling allowed all the plants to grow healthily. Therefore, it is concluded that N.RECS is a practical system that allows for both energy-saving cultivation in the winter and cooling cultivation in the summer. In addition, root-zone temperature is an environmental control parameter that should be controlled in future agricultural production; by applying root-zone temperature control as a standard technology for agricultural production, the growth of plants can be controlled more flexibly and more energy can be saved.

Design and Optimization of Air Inlet in Cuttings Incubator

“…Accordingly, this study used a thermostatic plate to heat the base of the cuttings to promote rooting, providing continuous ventilation to ensure a certain temperature difference between the upper and lower parts of the cuttings. In greenhouses, studies have used electric heating wires and plates to heat the substrate [60], and many have used rubber tubes or steam pipes to provide the heat [61][62][63]. Heating wires, tubes, or pipes heat the substrate unevenly; heating plates are better, but they can transfer heat from only one side.…”