Evaluation of the level of N supply in maize hybrids at different nutritional levels

Abstract

The aim of the research was to determine the effect of fertilisation and year on the SPAD value and on the dynamics of the SPAD value during the growing season.The results proved that the SPAD value steadily decreased over the growing season in a dry year, whereas it increased in a year with favourable precipitation. Fertilisation increased the SPAD values significantly (P<0.001). The significantly highest SPAD value, in both dry years and those with average rainfall, was achieved by applying 60 kg N ha−1fertiliser active ingredient at the 6-leaf stage, and 120 kg N ha−1at both the 12-leaf stage and the 50% silking stage.The correlation between fertilisation and SPAD values was greatly affected by the year, being closest in 2004 when there was an average precipitation supply, and weakest in 2007, the driest year. The correlation between the factors was weak at the 6-leaf stage, but became stronger as the vegetation period proceeded.As the growing season progressed, the SPAD values decreased in the dry year, but increased in the year with average precipitation supplies. Nutrient uptake was relatively intensive until the 12-leaf stage in the average year. In the dry year, the decrease in the SPAD value was the most intensive at the 50% silking stage.There was no stochastic correlation between the SPAD value measured at the 6-leaf stage and the yield, but the correlation between the two variables became stronger during the vegetation period.