Abstract

The chlorophyll (Chl) concentration of maize was compared to its grain yield and protein content in six different N treatments (0, 30, 60, 90, 120 and 150 kg N ha^-1) in a multifactorial field experiment with four replications and a split plot design in Eastern Hungary (47°33’ N, 21°26’ E, 111 m asl) in two years (2009 and 2010). Nitrogen fertilisation significantly (p < 0.001) increased Chl content in both years. In the dry year (2009), the Chl content did not increase as a result of N fertilisation above 120 kg N ha^-1, while the efficiency of higher N rates (150 kg N ha^-1) could be shown in the wet year (2010), varying per hybrid. The weather-induced abiotic stress effects on yield and protein content could be reduced by N fertilisation, but this required high input costs. In 2009, both hybrids were treated with the highest N fertiliser dose (150 kg N ha^-1) in order to reach the statistically highest yield (Mv 277 hybrid 6.76 t ha^-1; Kenéz hybrid 9.86 t ha^-1), and protein content (Mv 277 hybrid 10.2 g per 100 g dry matter; Kenéz hybrid 9.8 g per 100 g dry matter), while lower N fertiliser doses were enough in the favourable crop year of 2010. The correlation analysis results showed that weather parameters significantly influence the closeness of correlations, but are always positive. We concluded that the on-site measurement of leaf chlorophyll (SPAD) serves as a good indicator of the N demand of maize, as the difference between N-deficient and adequate N treatments is thereby more easily made. Therefore, the Chl content of maize leaf can be used effectively in developing recommendations for soil N replenishment.

Key words: Maize, fertilisation, chlorophyll concentration, protein content.