From leaf to fruit: Position-specific photosynthesis improves crop yield forecasts
image: Estimated and observed number of nodes and leaves emerged by thermal time (◦Cd) as estimated by the mode and leaf emergence model. Thermal time (◦Cd). A, B, C, and D are the results and data from experiments 1, 2, 3, and 4, respectively. The detailed model performance metrics (R2 and RMSE) for each experiment are described in the Results section
Credit: Horticulture Research
Accurately predicting how plants allocate dry matter to fruits remains a major challenge in crop modeling, especially under controlled greenhouse conditions. This study presents a new simulation framework that links photosynthetic performance to leaf position within the canopy, allowing dry matter partitioning to fruit to be predicted with greater precision. By integrating leaf-age–dependent gas exchange characteristics with plant growth dynamics, the model captures physiological differences that traditional canopy approaches often overlook. The results demonstrate that accounting for variation among upper, middle, and lower leaves substantially improves the accuracy and stability of fruit dry matter predictions. This approach offers a more realistic representation of plant carbon allocation and provides a stronger foundation for improving yield forecasting and crop management strategies.
Crop simulation models are widely used to support yield prediction, resource optimization, and greenhouse management. However, most existing models rely on simplified assumptions, treating photosynthesis as uniform across the canopy. In reality, leaf age, position, and cultivation conditions strongly influence photosynthetic capacity and assimilate production. In fruiting crops such as cucumber, yield is determined not only by total photosynthesis but also by how efficiently dry matter is partitioned to fruits. Ignoring spatial variation in leaf function can therefore lead to systematic prediction errors. Due to these limitations, there is a clear need to develop more physiologically realistic models that explicitly represent canopy heterogeneity and its impact on dry matter allocation.
Researchers from Kyungpook National University report a new crop simulation model that significantly improves predictions of fruit dry matter accumulation in greenhouse cucumbers. Published (DOI: 10.1093/hr/uhaf124) on 7 May 2025 in Horticulture Research, the study integrates leaf-position–specific photosynthesis with cropping-system differences to simulate canopy carbon allocation more accurately. By distinguishing the photosynthetic behavior of upper, middle, and lower leaves, the model outperforms conventional approaches that rely on a single representative leaf. The findings highlight the importance of physiological detail in crop modeling and point to new opportunities for precision greenhouse management.
The research combined detailed gas-exchange measurements with growth modeling to construct a canopy-level simulation framework that reflects physiological variation among leaves. Photosynthetic parameters were calibrated separately for upper, middle, and lower leaves under two greenhouse cropping systems, revealing clear declines in photosynthetic capacity with increasing leaf age. Leaves grown under semi-forcing conditions consistently showed higher photosynthetic potential than those under forcing conditions.
By embedding these leaf-position–specific characteristics into a coupled photosynthesis–growth model, the researchers simulated daily assimilate production and its allocation to fruits. When tested against multi-season experimental data, the new model achieved higher coefficients of determination and lower prediction errors than a conventional model that applied a single photosynthetic profile across the canopy. In particular, predictions of cumulative fruit dry matter closely matched measured harvest data, with improved consistency across different experiments.
The analysis showed that models ignoring leaf position tended to overestimate or underestimate fruit dry matter depending on conditions, whereas the position-specific approach produced more stable results. These findings demonstrate that incorporating spatial heterogeneity within the canopy is critical for accurately simulating carbon flow from photosynthesis to fruit growth.
“Our results show that leaves at different positions within the canopy do not contribute equally to fruit production,” said the study’s corresponding author. “By explicitly representing these physiological differences, we can better capture how plants actually allocate carbon under real greenhouse conditions. This moves crop modeling beyond simplified assumptions and toward tools that reflect how growers manage crops in practice. Such models can help bridge the gap between physiological understanding and practical decision-making.”
The proposed modeling framework has direct implications for greenhouse crop management. By linking photosynthesis to leaf position, the approach can support more precise decisions on temperature control, CO₂ enrichment, and defoliation strategies. Improved predictions of fruit dry matter accumulation also enhance yield forecasting and resource-use efficiency. Beyond cucumber production, the modeling strategy can be adapted to other fruiting crops with similar canopy structures. As climate variability and energy costs increase pressure on protected agriculture, physiologically informed simulation models such as this one offer a valuable tool for improving productivity while reducing inputs.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhaf124
Funding information
This study was conducted with financial assistance from the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry (IPET) through the Technology Development Program of the Ministry of Agriculture, Food, and Rural Affairs (MAFRA), South Korea (Project No. RS-2024-00399654).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.