ISHS Acta Horticulturae 761: XXVII International Horticultural Congress - IHC2006: International Symposium on Advances in Environmental Control, Automation and Cultivation Systems for Sustainable, High-Quality Crop Production under Protected Cultivation
ENVIRONMENTAL CONTROL IN GREENHOUSE BASED ON PHYTOMONITORING - LEAF TEMPERATURE AS A FACTOR CONTROLLING GREENHOUSE ENVIRONMENTS |
| Authors: | M.Y. Roh, Y.I. Nam, M.W. Cho, I.H. Yu, G.L. Choi, T.Y. Kim |
| Keywords: | Cucumis sativus, climate control, shading, heating, sap flow |
| Abstract:
Continuous and real-time monitoring of plant physiological responses to environmental changes is useful for controlling greenhouse environments precisely and made possible by using phytomonitoring systems recently. Phytomonitoring (leaf temperature and sap flow) and environmental (solar radiation, air and root-zone temperature, relative humidity, and wind velocity) data in cucumber plants (Cucumis sativus L.) grown at rockwool slabs were collected to examine the changes in leaf temperature under shading and heating and evaluate the leaf temperature as a factor controlling greenhouse environments. Over the shading period, leaf temperature maintained a lower level than air one. It was caused by the reduction in the direct solar radiation absorbed by leaves. Leaf temperature responded more rapidly than air one to the increases and decreases in solar radiation. Higher VPD increased the transpirational demand and consequently caused high reduction in leaf temperature. In low VPD, air and leaf temperature have a tendency to be similar. Under heating conditions during the nighttime, leaf temperature of cucumber plants was shown in the range of 13–17°C, while air temperature was maintained at 15–19°C. The leaf temperature of 13°C may cause the reduction in physiological activity of cucumber plants due to low temperature stress. The low leaf temperature during the night reduced the relative sap flow rate the following day. | |
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