Research on saving energy and high efficiency use by light environment control in the solar-artificial grean house

1996 Fiscal Year Final Research Report Summary

• Project/Area Number: 07556109
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 試験
• Research Field: 生物環境
• Research Institution: Gifu University
• Principal Investigator: ISHII Yukitsugu Gifu University, Faculty of Agriculture, Professor, 農学部, 教授 (40021711)
• Co-Investigator(Kenkyū-buntansha): HAGA Yutaka General Agricultural, Center at Gufu Prafectture, Group Reader, 野菜果樹部, 科長 ; TANAKA Itsuo Gifu University, Faculty of Agriculture, Asociate Professor, 農学部, 助教授 (10117161) ; MATSUI Syuitiro Gifu University, Faculty of Agriculture, Professor, 農学部, 教授 (30023451)
• Project Period (FY): 1995 – 1996
• Keywords: supplement ligh / spinach / sodium lamp / mercury lamp / artificial light control / stomata aperture / blue light / supplement time

Research Abstract

The cconomics of supplementing natural sunlight with additional light on cloudy days and effective methods of growing crops were investigated in a systems to grow spinach, a leafy vegetable, with the following results.
1. A feedback control system regulating the amount and quality of light was establisyed, with illumination provided by twin sodium and mercury lamps, with the light saturatiion point for green vegitables set at 250n mol/m^2/S.
2. Seven hours after exposing spinach to light levels of 250eta mol/m^2/S, the stomata aperture began to narrow. When the plants were later exposed to blue, green, and red light, the stomata aperture began to increase in blue light having a peak wavelenghth of 450 nm.
3. Based on the above results, illumination with mercury vapor lamps having a red/blue ratio of 0.9 was conducted for one hour immediately before sunrise, after which illumination having a red/blue ratio of 3 and exhiviting properties of natural sunlight combined with artificial light wa s added whenever levels of natural sunlight fell below set values. Regarding the period of artificial illumination, four groups were used in the study ; one receiving supplementary illumination in the first half of the day (with half the full day's set supplementary illmination period), one receiving supplementary illumination in the later half of the day ; one receiving supplementary illumination throughout the day ; and a group receiving no supplementary illumination. Regarding agronomic aspects, temperature, humidity, and concentration of carbon dioxide gas inside the greenhouse were controlled, with nutrient solution regulated at a pH of 5.5-5.6 and EC of 2.4mS/cm.
The rasults shown that the group receiving supplementary lighting only in the first half of the day had no significant difference in growth, either in termes of wet or dry weight, compared to the group receiving full-day supplementary lighting, and 30% lower consupmtion of electricty, this was shown to be an effective method of reducing energy use.