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BACKROUND Although changes in photosynthetic traits (PTs) during the long-term genetic improvement of soybean [Glycine max (L.) Merr.] yield have been studied, detailed information on whether PTs responses to environmental stress have improved and their correlations with seed yield are still unknown. Our objectives were to describe the changes in soybean PTs (leaf area index (LAI), leaf chlorophyll content (Chl), net photosynthetic rate (PN ), stomatal conductance (gs ) and transpiration rate (E) during decades of genetic improvement and to detect whether the responses of the PTs of 13 different soybean cultivars released in various decades to increasing fertilizer application rates (FRs) differed. RESULTS All the PTs of soybean increased significantly as the year of cultivars released increased under different FR treatments, indicating that PTs have improved during decades of genetic breeding. Medium FR (nitrogen) treatment (150 kg ha -1 ) increased PTs values, to different extents, at all the investigated growth stages. LAI, Chl and PN of old and middle cultivar group at the full bloom (R2), full seed (R6) and beginning maturity (R7) stages decreased significantly under the high FR treatment (300 kg ha-1 ) compared with the medium FR treatment. The former had no or promotive effects on any of the PTs of new cultivar group. Thus, the photosynthetic capacities of the new cultivars are more tolerant to high FR-related stress than older cultivars CONCLUSIONS: The photosynthetic capacities and the tolerance levels to high FR-related stress of soybean released in different years improved after long-term genetic breeding. This article is protected by copyright. All rights reserved.