Soil compaction induced iron‐chlorosis in grape vineyards: Presumed involvement of exogenous soil ethylene

The soil atmosphere of chlorotic and healthy vineyards showed no differences in the O2‐content during the growing season, but the chlorotic field contained significantly higher content of ethylene in the soil atmosphere. This gas in concentrations above 1 ppm is known to inhibit the elongation of grape‐roots completely. We hypothesized that the ethylene inhibited growth and elongation of roots and thus inhibited the uptake of iron, which can be taken up by the elongation root zone only. Chlorosis is induced by fast growing period when the suberized root system provides all other elements except iron. This type of chlorosis is increased by the addition of undecomposed organic material, which in laboratory experiments produces much more ethylene than decomposed matter. The “in vitro”; production is highly moisture dependent. The water content of the root zone of grapes can be reduced by implanting oil radish and thereby the chlorosis can be controlled.