|Authors: ||R. Baas, C. Slootweg|
|Keywords: ||transpiration, lysimeter, global radiation, light integral|
For on-line plant monitoring equipment to be functional in commercial glasshouse horticulture, relations between sensor readings and plant responses on both the short (days) and long term (weeks) are required.
For this reason, systems were installed to monitor rockwool grown gerbera plants on a minute-to-minute basis from July 2002 until April 2003. Data collected included, amongst others, crop transpiration from lysimeter data (2 m2), canopy temperature using infrared sensors, rockwool water content, and greenhouse climatic parameters, such as global radiation and temperature.
By combining data from lysimeter and water content, changes in crop fresh weight could be calculated on a daily basis.
Both transpiration and daily fresh weight production were better related to light integral as measured inside the greenhouse, than outside the greenhouse.
The contribution of heating pipes underneath the canopy to transpiration could be estimated with the system.
From the relation between daily FW production and previous day light integral, a light use efficiency of ca. 10-g FW/MJ solar radiation as measured inside the greenhouse was calculated.
Water use efficiency was on average 25 g FW/L. A 3-4 day drying cycle did not affect flower production.
The results underline the importance of knowledge on the adaptation and tolerance of crops to stressful conditions, in order to be able to use plant monitoring under grower conditions effectively.
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