A vetésidő hatása a kukorica- (Zea mays L.) hibridek terméshozamára és minőségére | The effect of sowing date on the yield and quality of maize (Zea mays L.) hybrids

Summary We examined the yield, protein- and starch content of maize in the Látókép Experimental Station of the University of Debrecen, Centre of Agricultural Sciences and Engineering on a medium-heavy calcareous chernozem soil in two different crop years – a drought year (2007) and a year with favourable water supply (2008) – in experiments sown at early, optimal and late sowing dates. The pH value of the experimental area is 6.6, whereas the value of soil texture (KA) is 37. The level of nitrogen and potassium supply of the soil is good and the level of P supply is average. The basic data were supplemented by pheno-, phytometric observations and soil analyses. The yield, protein- and starch content data are the results of the 24 hybrids that are listed among hybrids authorised for common production. We evaluated the data with the statistical software SPSS for Windows 13.0. Sowing date had a significant effect on yield in both years but its magnitude was different in each year. Of the main factors, (sowing date, hybrid), the date of sowing had the highest effect in 2007, whereas the effect of the given hybrid was stronger than that of sowing date in 2008. The significantly highest yield (6.111 t ha –¹) was observed in the case of optimal sowing date in the drought year (2007). In the year with favourable water supply (2008), we managed to achieve the highest yield result (8.910 t ha –¹) in the case of early sowing, but there was no significant difference between the yield results of the different sowing dates. In both years, the grain yields of the hybrids with longer growing periods was significantly higher (P < 0.05) than those with shorter ones. In the drought year (2007), mid-ripening (FAO 400) hybrids had the highest grain yield (6.596 t ha –¹), whereas in the year with favourable water supply (2008), the highest yields (9.864 t ha –¹) were observed in the case of late-ripening (FAO 500) hybrids. In the favourable year (2008), we measured lower protein content in high yields in comparison with lower yields in the drought year (2007). The highest protein content was measured in the case of late sowing date in 2007 (11,9 g × 100 g –¹ dry matter). In 2008, sowing date did not significantly influence protein content. The starch content of hybrids belonging to the very early-ripening (FAO 200) group was significantly (P < 0.001) higher in the case of all sowing dates and both years than those of early- (FAO 300), mid- (FAO 400) and late-ripening (FAO 500) hybrids. As for protein content, the biggest difference was observed between early and late sowing dates. In the year with favourable water supply (2008), none of the FAO groups’ protein contents changed significantly as a result of different sowing dates. There was a negative correlation between yield and protein content; protein content was lower in the year when we observed higher yield (2008), as opposed to the poorer year (2007). Sowing date significantly affected (P < 0.001) the starch content of maize grain in both years. Both in the drought year and the favourable one, there was a significant difference between the starch content values of hybrids (P < 0.001 in 2007, P < 0.05 in 2008). In 2007, the sowing date × hybrid interaction was significant and the starch content was higher, too. We measured a higher starch content in the dry year (2007) than in the year with favourable water supply (2008). At the same time, the highest starch content was measured in the case of late sowing date in both years (74.4 g × 100 g –¹ dry matter, 72.1 g × 100 g –¹ dry matter). The starch content of late-ripening (FAO 500) hybrids was significantly higher (P < 0.05) than that of those with a shorter growing period. The content values important from the aspect of utilisation can only be achieved with outstanding genetic background and production technology (sowing date).