On-the-go image processing system for real-time measurement of plant growth status

Background: For identifying the best growth conditions for plants, plant feature measurements is an important and commonly used indicator. Traditional plant feature measurements are destructive and laborious. In our previous study, an automatic system based on image-processing was developed, which could measure the features of plants non-destructively. However, the system is could not provide real-time information about individual plants due to its use of post image-processing. To enhance the practical use of the developed system, in this study, an on-the-go image acquisition and processing system was developed.

Methods: This system included an image measurement system and a real time image processing system. The image measurement system consisted of stepping motors, linear actuators and a real-time transmission camera. The stepping motor drove the linear actuators to move the camera on a constant distance based on Cartesian Coordinates. The real time image processing algorithm was programmed in MATLAB. The developed system was installed in plant factory, where lettuces were grown based on the ebb and flow method to estimate the fresh weight of individual lettuces in real-time using the image of leaf area for each lettuce obtained with RGB camera.

Results: The experimental testing showed that it was possible to measure the fresh weight of each lettuce in real-time with a satisfactory level of accuracy as compared to those obtained from the previous post­ processing-based system.

Discussions: There were some limitations in measuring the leaves over lapped by showing a difficulty in segmenting leaf images for individual lettuce. In future studies, different image processing methods such as the Object Based Image Analysis (OBIA) will be used to improve the system performance.

Conclusion: The experimental results demonstrated the satisfactory performance of the developed system. It was expected that the developed system would be a useful tool for precision management of plant grown in plant factory.