Effect of sowing date on the yield and quality of maize hybrids with different growing seasons

The yield, protein and starch content of Martonvásár maize hybrids belonging to different FAO groups were examined in experiments involving early, optimal and late sowing dates in two different years (drought — 2007, favourable water supplies — 2008) on a calcareous chernozem soil with loam texture at the Látókép Experimental Station of the Centre of Agricultural Sciences and Engineering, University of Debrecen.Sowing date had a significant effect on maize grain yield in the dry year. The grain yields of hybrids with longer growing periods were significantly higher than those with shorter growing periods in both years, but they reacted sensitively to the change in sowing date in the dry year. Due to the rainfall distribution in the growing season, sowing date did not modify the performance of the hybrids in the year with favourable water supplies. Sowing date had a significant effect on the grain protein content in the dry year, with significantly higher values after late sowing than after early or optimal sowing. Averaged over the sowing dates, the protein content of the FAO 200 hybrid was significantly higher in both years than that of hybrids in other FAO groups. In the dry year, the greatest difference in protein content could be observed between the early and late sowing dates for hybrids in all four FAO groups. A negative correlation was found between yield and protein content. Sowing date significantly increased the starch content of maize in the favourable year, with a significant difference between early and late sowing dates.In the dry year higher starch contents were recorded for all the hybrids and for all the sowing dates than in the favourable year. In the dry year, sowing date only caused a significant difference in the starch content in the case of FAO 200 sown at optimal and late sowing dates. In the favourable year, a significant difference was only obtained for the starch content of the FAO 400 hybrid sown at early and late sowing dates. Satisfactory quality can only be achieved if suitable genotypes are grown with appropriate technologies.