Semi-closed greenhouse photosynthesis measurements – A future standard in intelligent climate control

Abstract

However, all of these methods have severe limitations in terms of providing accurate measurements of the performance of a canopy in a large greenhouse. The methods employed will usually change the climate conditions in relation to those found in the greenhouse, and it therefore becomes difficult to interpret the measurements. In spite of these limitations, however, the different methods have provided much valuable knowledge on optimal climate conditions for different crops. So far, steady-state photosynthetic responses to environmental factors have been extensively studied, but knowledge of the effect of continuous variation in climate on photosynthesis remains scarce (Marcelis et al., 2014).With the introduction of semi-closed greenhouses, new possibilities have opened with respect to climate control and energy efficiency of greenhouses (Dannehl et al., 2014;Marcelis et al., 2014;Qian, 2017). With this type of greenhouse, the air exchange rate between the greenhouse and the outside environment can be measured, since the ventilation is controlled by fans in the greenhouse walls and not by roof vents. This gives rise to new possibilities with respect to continuously recording crop photosynthesis. Photosynthesis can be accurately measured by precisely measuring airflow, and the inlet and outlet CO 2 concentration in the air. Our objective was therefore to evaluate the potential of measuring canopy photosynthesis in a large semi-closed greenhouse. Although numerous semi-closed greenhouses have been built worldwide, this method of continuously monitoring crop respons-

Cherry Tomato Production in Intelligent Greenhouses—Sensors and AI for Control of Climate, Irrigation, Crop Yield, and Quality

“…Actuators then operate based on setpoints configured in a process computer, while sensors give feedback on measured data for the control loop. Additional sensors monitoring crop status are able to provide the grower with further information on photosynthesis rate [ 7 ], sap flow and hydraulic status [ 8 ] and leaf temperature [ 9 ] to be added to his manual decisions. Automated greenhouse climate control algorithms have already been developed in the past and are today widely introduced in modern high-tech greenhouses [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]; however, automated control on crop status are still in its infancy.…”