Articles
Theoretical evaluations of a data-driven tomato leaf pruning method based on weekly light integral at the lowest leaf
Article number
1423_15
Pages
113 – 120
Language
English
Abstract
The high-wire production system enables year-round, high-quality and high-yield production of crops such as tomato.
However, this system demands labor-intensive tasks such as clipping, suckering, and leaf pruning.
Leaf pruning is essential for controlling the source and sink balances.
Yet, little is known in determining the optimal timing of leaf pruning in commercial greenhouses.
Here, we introduce a data-driven leaf pruning method that executes leaf pruning if light intensity below the canopy is lower than light compensation point (LCP, 32 µmol m‑2 s‑1 PPFD for our plants). Due to temporal fluctuations in light intensity, we employed weekly LCP to determine the pruning timing. ‘Maxxiany’ tomato plants were grown in a Venlo-style greenhouse (464 m2 and 7-m gutter height) at 3 plants m‑2, and day/night temperature setpoint of 24/18°C. Daily light integral (DLI) over the canopy ranged between 6 and 33 mol m‑2 d‑1. Using crop measurements after fifth truss and light extinction coefficient, models were developed to simulate DLI at the lowest leaf and leaf number under different leaf pruning scenarios.
Timing of leaf pruning was decided based comparison between DLI or weekly light integral (WLI) at the lowest leaf and the daily or weekly LCP. To develop an optimal method, pruning scenarios, including conventional pruning (removing leaves below a fruiting truss), DLI-based pruning, WLI-based pruning, and WLI-based pruning with a minimum one-week interval, were tested using the model.
All scenarios adopt three leaves removal at each pruning event to follow the commercial practice.
The simulation suggests WLI-based pruning with a minimum one-week interval is the optimal leaf pruning method, considering its frequency and number of pruning events over the cropping cycle.
We have evaluated the WLI-based method in the greenhouse by comparing its performance to the conventional method.
Overall, the WLI-based method resulted in a significant reduction in the number of pruning events and labor input by 25-50% compared to the conventional method.
However, this system demands labor-intensive tasks such as clipping, suckering, and leaf pruning.
Leaf pruning is essential for controlling the source and sink balances.
Yet, little is known in determining the optimal timing of leaf pruning in commercial greenhouses.
Here, we introduce a data-driven leaf pruning method that executes leaf pruning if light intensity below the canopy is lower than light compensation point (LCP, 32 µmol m‑2 s‑1 PPFD for our plants). Due to temporal fluctuations in light intensity, we employed weekly LCP to determine the pruning timing. ‘Maxxiany’ tomato plants were grown in a Venlo-style greenhouse (464 m2 and 7-m gutter height) at 3 plants m‑2, and day/night temperature setpoint of 24/18°C. Daily light integral (DLI) over the canopy ranged between 6 and 33 mol m‑2 d‑1. Using crop measurements after fifth truss and light extinction coefficient, models were developed to simulate DLI at the lowest leaf and leaf number under different leaf pruning scenarios.
Timing of leaf pruning was decided based comparison between DLI or weekly light integral (WLI) at the lowest leaf and the daily or weekly LCP. To develop an optimal method, pruning scenarios, including conventional pruning (removing leaves below a fruiting truss), DLI-based pruning, WLI-based pruning, and WLI-based pruning with a minimum one-week interval, were tested using the model.
All scenarios adopt three leaves removal at each pruning event to follow the commercial practice.
The simulation suggests WLI-based pruning with a minimum one-week interval is the optimal leaf pruning method, considering its frequency and number of pruning events over the cropping cycle.
We have evaluated the WLI-based method in the greenhouse by comparing its performance to the conventional method.
Overall, the WLI-based method resulted in a significant reduction in the number of pruning events and labor input by 25-50% compared to the conventional method.
Authors
C. Kim, C. Kubota
Keywords
leaf pruning, high-wire tomato production, weekly light integral
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