Die Bodenkultur - Journal for Land Management, Food and Environment


New iron fertilizers for control of chlorosis in grape vine (Vitis vinifera L.)


In two year pot experiments the effect of new iron fertilizers on chlorosis were tested with a susceptible and a non susceptible grape vine rootstock, which were grown on a calcareous soil. The iron sources FeEDTA, FeS04 and a combination of both were coated with a natural resin material, which allows water to penetrate the resin coating and slowly release iron over a six month period. For corriparing the new iron fertilizers with a commonly used fertilizer Sequestren 138 with FeEDDHA as Fe-chelat was used. In laboratory experiments the solubility of the new fertilizers were tested by leaching fertilized soil and sand. The effectiveness of the fertilizers on chlorosis was measured by the content of Fe, Cu, Zn and Mn, of chlorophyll and organic acids in the youngest leaves. The iron concentration in the eluent of the leaching experiments as well as in the soil solution prove a higher availability of iron for plants due to fertilizing the soil with Sequestren, Prototype 1 (coated FeEDTA) and Prototype 111 (coated FeEDTA + FeS04). In all iron treatments the iron content of the youngest leaves increased, but significantly only in the Sequestren 138 treatment. Although the increase of the iron content in the Prototype land 111 treatments were not as high as in the Sequestren treatment a clear positive effect on chlorosis was obvious. The content of chlorophyll increased evidently while the content of organic acids decreased and no chlorosis symptoms occurred. Chlorosis symptoms appeared in the control and in the FeS04 treatment. In all iron fertilizer treatments a strong Fe: Mn antagonism was found. Key words: grape vine, chlorosis, iron fertilizer.