IRON SUPPLY OF CUCUMBERS IN SUBSTRATE CULTURE WITH HUMATE

The aim of the experiments was to investigate the effect of application of a well soluble Fe-humate (HUMIRON^®) on rhizosphere and leaves, respectively, on the growth and yield of cucumbers (Cucumis sativus cv. Jessica). HUMIRON^® type R (extracted from Russian coal) and G (extracted from German coal) were compared. In the first experiment three different concentrations (0.001%, 0.1%, and 0.2%) of HUMIRON^® were used in three different growing stages of cucumber plants. In the second experiment HUMIRON-G^® and K-humate were applied to the upper or lower surface of the cucumber leaves. Cucumbers were grown in a substrate culture used containers with 8 l perlite. Nutrient solution with and without iron was applied with trickle irrigation. The results clearly show the application of Fe-humate has beneficial effects on the plant growth and the fruit yield if the nutrient solution had a lack of iron. Iron imbalances or deficiency can be counteracted by application of Fe-humate to the root zone. The additional iron supply did not inhibit the growth and decrease the yield even if the iron supply in the nutrient solution is sufficient. The different effects of the humate types (HUMIRON R and G, K-humate) compared here indicate that the influence of humate can be important