Improvement of Iron Uptake in Table Grape by Addition of Humic Substances

ABSTRACT

Two experiments in consecutive years were conducted at a table grape plantation located in southeastern Spain. The objective was to test whether the addition of commercial organic compounds could improve the uptake of iron (Fe) by plants. A commercial humic substance and two mixtures of amino acids were used as organic compounds in the first experiment and FeEDDHA was the source of Fe. The joint addition of FeEDDHA and organic compounds improved Fe nutrition. The humic substance was more effective than the amino acids in increasing Fe uptake. In the following year, a similar experiment was conducted by progressively replacing part of the chelate with the humic substance. An increase in foliar Fe and phosphorus (P) and a decrease in sodium (Na) levels were observed. The best results with respect to nutrient foliar content and nutrient relationships were obtained for a range of substitutions for the chelate by the humic substance of from 30% to 50% with no loss in yield or fruit quality.

Keywords:

• amino acids
• FeEDDHA
• humic compounds
• iron chlorosis
• table grape

ACKNOWLEDGMENTS

This work was supported by project AGF98-0177-C02-02 from the Comisión Interministerial de Ciencia y Tecnología (MEC, Spain).

Notes

^a P was extracted by the method of Burriel and Hernando (1947).

^b These elements were extracted with ammonic acetate.

^c Micronutrients were extracted by the method of Lindsay and Norvell (1978).

*0.01 < sig < 0.05;

**0.001 < sig < 0.01;

***sig < 0.001.