The effect of sowing date on maize development and yield was studied in field experiments. The experiment was set up at the experimental garden of the University of Debrecen Centre of Agricultural Sciences Faculty of Agriculture, Department of Plant Sciences in 2005 and 2006 on calcareous chernozem soil. Six hybrids with different genetic characteristics and vegetation period were tested (Sze 269, DK 440, PR37D25, NK Cisko, Mv Maraton, PR34B97) at three different sowing dates.
2005 was a very wet year. The amount of precipitation in the vegetation period was about 150 mm higher than the average of 30 years. No significant differences were observed in temperature. However, the number of sunny hours was much lower during the summer than as usual. This had an influence on yields.
In 2006, there was no risk of inland water in spite of the large amount of precipitation at the beginning of the year. The amount of water available for plants was satisfactory during the season due to the favorable amount of precipitation. Therefore, plants suffered less from the heat in July. However, hail on 22 July caused significant damage. The number of sunny hours in the summer was high enough. The warm, dry autumn helped the water release of plants.
In 2005, the results of the third sowing date could not be evaluated due to the large number of missing plants. The yield of hybrids ranged between 12-14 t/ha for the first sowing date. For the second sowing date, yields ranged between wider boundaries. The hybrid PR37D25 has a very high yield in the case of the second sowing date, and its seed moisture content was favorably low. The yield of hybrid PR34B97 was the lowest at the later sowing date, the prime reason of this was damage caused by Diabrotica virgifera. The seed moisture content at harvest varied between 16-24% for the first sowing date. In the case of the second sowing date, higher values were measured. Hybrids Sze 269 and NK Cisko had favorable water release characteristics. The maximum value of leaf area index was the best in the case of the first sowing date (5-5.5 m2/m2).
In 2006, yields for the first sowing date ranged between 8-10 t/ha. At the second sowing date, more favorable results were obtained. The reason for this is probably that hail caused a higher damage in hybrids with the early sowing date. Plant stock with later sowing date could recover more successfully. Hybrid PR37D25 had very high yields for the second and third sowing dates. The high-yielding hybrid PR34B97 also had high yield, but this was accompanied by higher seed moisture content. Due to the warm, sunny autumn weather, the hybrids had good water-release dynamics and were harvested with a lower seed moisture content than in the previous year. For the first sowing date, the seed moisture content was around 13-14% except for hybrid PR34B97. For the second and third sowing dates, higher values were observed. Leaf area index was significantly reduced in August for all three hybrids due to the hail in July. For the first two sowing dates, the leaves of hybrid Sze 269 were the first to dry similarly to the previous year.
Year had a strong effect on the results in both years.