The examination of maize hybrids of different genotype and ripening date (Sarolta, P 9175, SY Afinity) was performed in the case of different row spacing (45 cm, 76 cm) and crop density (50, 70 and 90 plants per hectare) in two different crop years (2013, 2014) on calcareous chernozem soil in the Hajdúság region of Hungary. The obtained examination results showed that the modern maize hybrids responded favourably to increasing crop density. In 2013, when water supply was favourable, the optimal crop density was shown to be 90 thousand plants per hectare in the case of 45 cm row spacing, while in the less favourable year of 2014, it was again 90 thousand plants per hectare which was optimal at 76 cm row spacing (maximum yield were 12 875–17 595 kg ha-1 and 12 149–15 334 kg ha-1 for each hybrid, respectively). LAImax was between 4.1–4.7 m2 m-2 in 2013 and 4.4–4.5 m2 m-2 in 2014. SPADmax was between 55.7–60.9 and 61.6–64.3 in the optimal row spacing and crop density treatments, respectively. Increasing crop density increased LAI in both years. SPAD readings decreased in 2013, while they did not change as a result of increasing crop density in

2014. The photosynthetic capacity index (Ph.C.=P index) developed by the authors of this paper could be perfectly used to characterise the impact of crop year and growing area, as well as crop density. Pearson’s correlation analysis was used to demonstrate a close correlation between the yield of maize hybrids and the P index (0.829**-0.866**) and a moderate correlation between yield and LAImax (0.440**-0.579**). According to the performed examinations, there was no correlation between yield and SPADmax readings (-0.252–+0.094).

Keywords: maize, row spacing, crop density, yield, LAI, SPAD, P index