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Photosynthetically active radiation (PAR) intercepted by potato plants was above 96% at 50 days after planting and declined by about 5% with crop age. 80-90% of incident PAR was intercepted by the top half of the plant. Net photosynthetic rate declined by 21 to 53.3% at middle and bottom leaf positions respectively as compared to the 4th leaf from the top. High yielding cultivars maintained high photosynthetic rates at all leaf position as compared to low yielding ones.
