ロックウール粒状綿を利用した養液栽培システムにおける高糖度トマト生産 （第１報） 水切り下における植物生体情報の測定と解析

Abstract

The authors are making researches for production of tomato fruits with high Brix in nutrient solution cultivation system with granular rockwool. As the first step of the researches, physiological information of tomato plants under water stress was measured and analyzed.Tomato plants (Lycopersicon esculentum Mill. cv. Hausu-Momotaro) were grown in the nutrient solution cultivation system with granular rockwool in a glasshouse in Ehime University. Measurements of water potential of leaf, transpiration rate, photosynthetic rate, stem diameter and leaf temperature of the tomato plants were made on December 3rd of 1996. It was sunny on the day and no nutrient solution supply was made from 0 : 00 of the day in the no irrigation treatment.The water potential of leaf in the no irrigation treatment was lower than that in the control treatment. Difference between the two treatments of the water potential of upper leaf was 0.08 MPa and that of lower leaf was 0.7 MPa at 14 : 30. The transpiration rate in the no irrigation treatment was much lower than that in the control treatment after 10 : 30. While the stem diameter in the control treatment decreased by only 0.1 mm, the stem diameter in the no irrigation treatment decreased by 0.7 mm. The leaf temperature in the no irrigation treatment at 10 : 30 was 3.6°C higher than that in the control treatment. It was considered that this difference was caused by the difference of the transpiration rate.Furthermore, relationships between the water potential of leaf and the other factors were analyzed. As the results, it was considered that the water potential of leaf could be estimated by the stem diameter or the accumulated solar radiation.