Current Usage of Air Circulators in Greenhouses in Japan

Kuroyanagi, Takeshi

doi:10.6090/jarq.50.7

Cited by 8 publications

(2 citation statements)

References 12 publications

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“…Horizontal and vertical temperature differences in greenhouses should be reduced and many temperature control methods have been tested to achieve a uniform temperature by changing the position of the heating pipes or by using a circulator (Fernandez and Bailey, 1994;Jeff and Jones, 1973;Kuroyanagi, 2016;Teitel and Tanny, 1998). However, having a temperature is not absolutely essential for adequate plant growth, as roots and flowers (the most temperature-sensitive organs) only occupy a small space in the greenhouse.…”

Section: Introductionmentioning

confidence: 99%

Local Temperature Control in Greenhouse Vegetable Production

Kawasaki

Yoneda

2019

Hortic J

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Uniform temperature throughout a greenhouse is recommended, as the present climate control method and many other studies have shown that the temperature gradient decreases vertically and horizontally in a greenhouse. However, recent research revealed that roots, fruits, flowers, and shoot-tips are more sensitive to temperature changes than leaves and stems, indicating that uniform temperature control may not be necessary. In addition, energy-saving techniques that do not lead to yield loss are desirable to reduce energy costs and ensure sustainable greenhouse production. In this paper, we review current studies on local temperature control methods in greenhouse vegetable production, primarily focusing on the tomato, and compare them with novel climate-control techniques. Roots, fruits, shoot-tips, and flowers are sensitive to temperature changes, showing negative symptoms under extreme temperature conditions. Therefore, the temperature of these plant organs should be controlled locally. Root zone temperature control enhances root growth and its associated physiological activities, promoting uptake of water and mineral nutrients. This subsequently leads to enhanced growth of shoots. Fruit temperature control may not be effective for tomato plants, but it promotes fruit growth and fruit sugar accumulation in melons and watermelons. Shoot-tip temperature control promotes the differentiation of leaf and flower buds. Flower temperature control enhances pollen viability and promotes fruit set. The combination of shoot-tip and flower heating enables low energy consumption compared with conventional heating, without loss of yield. Local temperature control techniques (except roots) have been studied in recent years; however, there is a distinct lack of research on the physiological mechanisms and practical approaches to develop a better local temperature control system. Thus, further studies are required on this area in the future.

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Section: Introductionmentioning

confidence: 99%

Local Temperature Control in Greenhouse Vegetable Production

Kawasaki

Yoneda

2019

Hortic J

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“…Airflow movement improves the consistency of temperature, humidity, and CO 2 in greenhouses (Kuroyanagi, 2016).…”

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confidence: 99%

Design of an Air Blowing Device Above Seedbed: The Effect of Air Disturbance on the Microenvironment and Growth of Tomato Seedlings

Li¹,

Li²,

Wu³

et al. 2020

horts

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In recent years, air circulation has been used in protected cultivation to improve the microenvironment around seedlings, which in turn enhances photosynthesis and seedling growth. However, a practical and precise air circulation device has not yet been reported, especially one for growing seedlings in a greenhouse. Considering the use of a seedbed in seedling cultivation, a blower that can move back and forth on the seedbed and accurately control the air velocity is designed. In this experiment, we take the nonblowing treatment as the control (CK); three air velocities (0.3, 0.6, and 0.9 m/s) were selected to investigate the effect of interval blowing on the microenvironment of the canopy, physiology of seedling growth, stomatal characteristics of leaves, and stem mechanics of tomato seedlings. The three air velocities were found to significantly reduce the canopy temperature by 0.44, 0.78, and 1.48 °C lower than the CK, respectively, and leaf temperature by 0.83, 1.57, and 2.27 °C lower than the CK, respectively, in cultivated seedlings during summer. The relative humidity of the tomato seedling canopy decreased by 2.7% to 7.0%. Compared with the CK, the plant height of tomato seedlings decreased by 13.54% and root dry mass, root-shoot ratio, and seedling quality index (SQI) increased by 34.63%, 21.43%, and 14.29%, respectively, at 0.6 m/s. In addition, mechanical indexes such as hardness and elasticity of the tomato seedling stem were higher under air disturbance than those of the CK. The best effect was seen in the treatment with the air velocity of 0.6 m/s, in which the hardness and elasticity of the stem base and the first node were significantly higher than that of the CK. In conclusion, air disturbance generated by the air blowing device we designed effectively improved the microenvironment around the plants, enhanced the physiological activity of the seedlings, and thereby promoted seedling growth.

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