Light distribution within canopies is important for plant growth. This study aimed to quantify the influence of row orientation on inter- and within-row variation of light absorption and photosynthesis in a hedgerow crop. An experiment with two row orientations of a tomato crop was conducted which was then used to calibrate a functional-structural plant model (FSPM). The FSPM was used to analyze light absorption and photosynthesis for each of the row facing directions in the double row trellis system (e.g. north- and south-facing rows for the east-west row orientation).
The measured leaf area decreased by 18% and SLA by 10%, while fruit dry weight increased by 7% for south-facing compared to north-facing rows, but total plant dry weight did not significantly differ. Model simulations showed a 7% higher light absorption for the south-facing rows than north-facing rows, while net photosynthesis was surprisingly -4% lower, due to local light saturation. When in the model leaf area was kept equal between the rows, light absorption for the south-facing rows was 19% and net photosynthesis 8% higher than for north-facing rows.
The team concluded that although south-facing rows would be expected to have a higher photosynthesis than north-facing rows, plants can adapt their morphology such that differences in light absorption and photosynthesis between north- and south-facing rows are minimal. Rows oriented north-south were more uniform in light absorption and photosynthesis than east-west rows, but the overall crop light absorption and photosynthesis were minimally affected (both 3% lower compared to east-west orientation) .
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Meer, M & Visser, P & Heuvelink, E & Marcelis, L.F.M.. (2021). Row orientation affects the uniformity of light absorption, but hardly affects crop photosynthesis in hedgerow tomato crops. in silico Plants. 10.1093/insilicoplants/diab025.