Cyclic hydroxamic acids (cHx) are metabolites of species belonging to the Poaceae family. These compounds play an important role in the natural protection against pathogens and pests. There can be remarkable differences amongst the varieties of cultivated species in their cHx content. Higher cHx content may enhance the self-protection ability of the variety. Therefore, the quality of self-protection of different varieties can be forecast by measuring their cHx content. The cHx contents of five Pioneer maize hybrids were compared in our experiments. The amount of these compounds in the plant organs was measured in different development stages. Significant differences in the cHx content of the organs were found in the following order: leaves, tassel, ear and root, respectively. The detected cHx contents of the leaves and roots decreased with age. Hybrids were compared to each other on the basis of the organs with the highest cHx content, i.e., the young leaf samples. The measured cHx contents of three hybrids appeared to be significantly higher than the others: these hybrids were P9578, PR36K67 and PR36V52. In contrast, the cHx content of hybrid P9494 was significantly lower than these three hybrids, while the hybrid PR38A79 was characterised with the significantly lowest cHx content amongst the examined varieties. Further investigations are required for the evaluation of the correlation between the cHx content and the resistance of the examined hybrids to diseases and pests.

Keywords: Pioneer maize hybrids, cyclic hydroxamic acid