The article deals with the influence of plant density and the use of Extrasol, microbiological fertilizer, on photosynthetic activity and productivity of corn hybrids of different ripeness groups in the Lower Volga region. The results indicate that an increase in plant density up to 65,000 plants/ha contributes to an increase in the studied parameters. The leaf area of Ross 197 MB, Ross 299 MB, and STK 175 corn hybrids with thickening was 35,220.9 m2/ha, 40,168.4 m2/ha and 44,540.1 m2/ha, respectively; the photosynthetic potential of Ross 197 MV - 2.1 million m2/ha per day, Ross 299 MV - 2.10 million m2/ha per day, and STK 175 - 2.27 million m2/ha per day; grain yield for Ross 197 MV is 6.90 t/ha, for Ross 299 MV – 6.37 t/ha, for STK 175 – 7.81 t/ha. The use of Extrasol promoted an increase in the leaf area by 1630.6-2257.9 m2/ha and the photosynthetic potential of hybrids by 0.27-0.97 million m2/ha per day.