Articles
THE PLANTS-ON-LINE-BOX: MONITORING WHOLE PLANT NET PHOTOSYNTHESIS AS A TOOL TO EVALUATE PLANT PRODUCTIVITY AND STRESS IN BEGONIA ELATIOR VAR ‘ILONA’
Article number
421_14
Pages
145 – 154
Language
Abstract
The main purpose of the experiment was to test a newly developed computer-based whole plant photosynthesis measurement system and evaluate it as a tool for biologically based decision support for plant production in greenhouses.
To enable the greenhouse grower to relate to photosynthetic measurements two new model-based indices were developed: the Productivity IndeX (PIX) and the Theoretical Photosynthetic Maximum Rate (TPMR). The PIX expresses the extent to which the measured accumulated crop photosynthesis during the half hour measuring time is equal to the expected simulated crop photosynthesis.
The TPMR expresses the potential maximum crop photosynthesis given optimal CO2 concentration and irradiance.
To test the behaviour of these two indices Begonia elatior plants were grown for a period of 90 days and photosynthesis was measured in a developed measurement environment called the Plants-On-Line-Box (POL-box) twice a week and the trends in productivity were monitored.
Further, one begonia crop was stressed with increasing electric conductivity (EC) in the nutrient solution to investigate if the photosynthetic indices could function as an early warning indicator for nutrient induced plant stress.
The results showed that it was possible to measure the photosynthetic behaviour of the crop, that definite variations in TPMR and PIX occurred, and that these fluctuations were difficult to interpret.
Plant stress in Begonia elatior induced by high EC was not detected in the photosynthetic capacity of the crop.
Experience from using the POL-box shows the importance of defining the measurement conditions – climatic as well as biological – before it is possible to evaluate and compare biological measurements from one crop with another and use these measurements as a sound basis for greenhouse management decisions.
To enable the greenhouse grower to relate to photosynthetic measurements two new model-based indices were developed: the Productivity IndeX (PIX) and the Theoretical Photosynthetic Maximum Rate (TPMR). The PIX expresses the extent to which the measured accumulated crop photosynthesis during the half hour measuring time is equal to the expected simulated crop photosynthesis.
The TPMR expresses the potential maximum crop photosynthesis given optimal CO2 concentration and irradiance.
To test the behaviour of these two indices Begonia elatior plants were grown for a period of 90 days and photosynthesis was measured in a developed measurement environment called the Plants-On-Line-Box (POL-box) twice a week and the trends in productivity were monitored.
Further, one begonia crop was stressed with increasing electric conductivity (EC) in the nutrient solution to investigate if the photosynthetic indices could function as an early warning indicator for nutrient induced plant stress.
The results showed that it was possible to measure the photosynthetic behaviour of the crop, that definite variations in TPMR and PIX occurred, and that these fluctuations were difficult to interpret.
Plant stress in Begonia elatior induced by high EC was not detected in the photosynthetic capacity of the crop.
Experience from using the POL-box shows the importance of defining the measurement conditions – climatic as well as biological – before it is possible to evaluate and compare biological measurements from one crop with another and use these measurements as a sound basis for greenhouse management decisions.
Authors
N. Ehler, J. Mazanti Hansen
Keywords
models, plant productivity, greenhouse management, POL-box
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