|Budget Amount *help
¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1990 : ¥100,000 (Direct Cost : ¥100,000)
Fiscal Year 1989 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Growth and yield of crops largely depend on their photosynthetic ability, which is also influenced by environmental conditions. Growing crops in NFT is usually carried out in a glasshouse and environmental conditions are highly controlled to avoid environmental stresses. Particularly, conditions of rizosphere are quite different from those in soil. From these facts, it becomes important to evaluate a degree of importance of factors in regulating ability of photosynthesis and transpiration and to find a difference in mode of response of crops to environmental factors between NFT and soil culture.
We measured rate of photosynthesis and transpiration of tomato plants growing in NFT in a glasshouse and changes in environmental factors, thereby analyzing relationships among them by the method of standard partial regression analysis.
In summer, effect of light on photosythesis or transpiration depended on intensity ; positive effects of light intensity increased at lower light intensities, while temperature factors became important at higher light intensities. In winter, response to light condition differed in a different plant age ; temperature factors played a positive role in photosynthesis and transpiration in old plants, while, in young plants, light intensity was a major factor in promoting photosynthesis and transpiration rate.
To find out a major factor in regulating photosynthesis and transpiration, further measurements at different seasons or different plant ages are needed, thereby providing a guideline for growing tomato plants in NFT. In addition to tomato plants, these attempts are needed to be made on other vegetable crops.