Articles
Development of an automatic water-stress control system by image analysis for the production of high-quality tomato
Article number
1296_129
Pages
1027 – 1034
Language
English
Abstract
For the production of high-quality tomato fruit (i.e., fruit with high sugar content), it is necessary to apply water absorption stress through irrigation restriction.
However, excessive deficit irrigation (DI) often leads to severe growth inhibition and irreversible wilting; therefore, stable production of high-quality tomato requires frequent observation and irrigation control by growers, making the process labor intensive.
In the present study, we aimed to develop an automatic system of water-stress control by image analysis.
First, we subjected tomato plants to DI treatment manually in a summer greenhouse and automatically captured tomato canopy images using an overhead camera every 1 min.
Using an original software, we determined the projected leaf area (PLA) from the canopy images under various natural light conditions and calculated the wilting ratio (W; percentage of PLA per non-wilting PLA in the early morning). During this period, we randomly measured the leaf water potential (LWP) destructively at various wilting stages.
The results revealed a significant negative correlation between the W (0-25%) and LWP (-0.2 to -1.5 MPa). According to the manual irrigation timing, the appropriate range of the setting value of W and LWP for irrigation was 15 to 20% and -1.02 to -1.21 MPa, respectively.
Next, we installed this software into an irrigation system and controlled the W under DI treatment, as a measure of water-stress level of tomato canopy, automatically for a few months.
The Brix percentage of tomato under DI was higher (8.0%) than that of tomato under sufficient irrigation (control) (5.5%) and the total yield under DI was 40% that of the control.
Overall, appropriate LWP for other canopies or in other greenhouses can be adjusted using the W calculated from photo-images.
In conclusion, we developed a control system of plant water-stress level by photo-image analysis for stable high-quality tomato production.
However, excessive deficit irrigation (DI) often leads to severe growth inhibition and irreversible wilting; therefore, stable production of high-quality tomato requires frequent observation and irrigation control by growers, making the process labor intensive.
In the present study, we aimed to develop an automatic system of water-stress control by image analysis.
First, we subjected tomato plants to DI treatment manually in a summer greenhouse and automatically captured tomato canopy images using an overhead camera every 1 min.
Using an original software, we determined the projected leaf area (PLA) from the canopy images under various natural light conditions and calculated the wilting ratio (W; percentage of PLA per non-wilting PLA in the early morning). During this period, we randomly measured the leaf water potential (LWP) destructively at various wilting stages.
The results revealed a significant negative correlation between the W (0-25%) and LWP (-0.2 to -1.5 MPa). According to the manual irrigation timing, the appropriate range of the setting value of W and LWP for irrigation was 15 to 20% and -1.02 to -1.21 MPa, respectively.
Next, we installed this software into an irrigation system and controlled the W under DI treatment, as a measure of water-stress level of tomato canopy, automatically for a few months.
The Brix percentage of tomato under DI was higher (8.0%) than that of tomato under sufficient irrigation (control) (5.5%) and the total yield under DI was 40% that of the control.
Overall, appropriate LWP for other canopies or in other greenhouses can be adjusted using the W calculated from photo-images.
In conclusion, we developed a control system of plant water-stress level by photo-image analysis for stable high-quality tomato production.
Publication
Authors
S. Hikosaka, K. Inoue, Y. Ishigami, E. Goto
Keywords
canopy image, deficit irrigation, high-sugar content, leaf water potential, wilting ratio
Groups involved
- Division Precision Horticulture and Engineering
- Division Greenhouse and Indoor Production Horticulture
- Working Group Organic Greenhouse Horticulture
- Working Group Protected Cultivation, Nettings and Screens for Mild Climates
- Working Group Light in Horticulture
- Working Group Vegetable Grafting
- Working Group Computational Fluid Dynamics in Agriculture
- Working Group Mechanization, Digitization, Sensing and Robotics
- Working Group Modelling Plant Growth, Environmental Control, Greenhouse Environment
- Working Group Greenhouse Environment and Climate Control
- Working Group Design and Automation in Integrated Indoor Production Systems
- Commission Agroecology and Organic Farming Systems
- Division Landscape and Urban Horticulture
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