Effect of plant density and row spacing on maize (Zea mays L.) grain yield in different crop year

Nowadays the aim of crop production is to realize the highest possible yield per production area unit by the highest possible crop safety. One of the possible ways for this is to increase of plant density or to decrease row spacing. Therefore, the plant number per unit area can be increased and the potential yield loss of individual plants is compensated by the higher plant density. The development of yield amounts of eight different genotypes was investigated in a small-plot field experiment with four replications on a calcareous chernozem soil type at the Látókép Research Site of the University of Debrecen in the crop years 2013 and 2014. Row distances of 45 and 76 cm, just as plant densities of 50 000, 70 000 and 90 000 plants per ha were set. Significant differences were found between the yield amounts of the studied hybrids in both studied crop years, while the effect of plant density on yield amount showed different results. In the crop year of 2013 the hybrids resulted high yields in the treatment with a row distance of 45 cm and plant density of 90 000 plants per ha, however, in 2014 significant yield decrease was found in comparison with the previous year, that can be attributed to the weather conditions in the months April-May and June. Optimal plant densities of hybrids, just as the corresponding expectable yield amounts were determined with quadratic equations. Optimal plant densities of the hybrids were different in the two studied crop years: in 2013, regarding the treatments set with the row distance of 45 cm, increasing plant densities resulted in higher yields, while in 2014, the yield showed decreasing tendency parallel to the increasing plant densities, that is confirmed by the fact that plant densities of 50 000 and 65 000 plants ha-1 proved to be more favourable. Regarding the treatments with a row distance of 76 cm, hybrids obtained their yield maximums by 80 327 plants ha-1 in 2013, while in the vegetation of 2014, by higher plant density (85 845 plants ha-1).