Cyclic hydroxamic acid content, exudation and the development of six Hungarian rye cultivars were investigated. The examined varieties were Kisvárdai alacsony, Kisvárdai legelő, Várda, Kriszta, Lovászpatonai and Ryefood. Plants were cultivated on nutrient solution, in climate chamber under regulated environmental circumstances. Sampling was carried out at the 8, 15 and 22 days of plant age. The content and the exudated amount of cyclic hydroxamic acids were measured by spectrophotometric method.

Significant differences were detected amongst cultivars in the rate of development. Kriszta showed slower rate of development than other cultivars.

It was measured that the cyclic hydoxamic acid content of roots was lower than that of the shoots in the case of every variety in the examined plant ages. Variety and plant age and the interaction of these factors caused significant effect on the cyclic hydoxamic acid content of shoots. It was significantly higher in the case of 8 days old plants than in case of 15 or 22 days old ones. There was no difference in the cyclic hydroxamic acid content of shoots between the 15- and 22-day-old plants. The highest cyclic hydroxamic acid content was measured in cultivar Kriszta. Plant age had a significant effect on the cyclic hydoxamic acid content of roots, but variety as a factor had not. There was no difference between the cyclic hydoxamic acid content of roots of 8 and 15 days old plants. In contrast with this statement, the 22-day-old plants had significantly lower root’s cyclic hydoxamic acid content than that of the 8- or 15-day-old ones.

Plant age and interaction of plant age and variety significantly influenced the cyclic hydoxamic exudation of roots, but variety alone did not. It can be concluded that the effect of plant age manifested on various ways in case of different varieties. Stagnation, increase, decrease and irregular change occurred at different examined varieties.

On the basis of our results there was no connection between the exudated amount and the

cyclic hydoxamic acid content of roots.

According to our expectations the results of this study can help to elucidate the background of diverse resistance and allelopathic properties of rye varieties.

Keywords: rye varieties, cyclic hydroxamic acid content and exudation