LIME-INDUCED chlorosis is a well known nutritional disorder of species growing on calcareous soils. The overt symptoms are the development of interveinal chloroses, which are commonly more severe in young leaves. Only in severe cases are the veins themselves chlorotic. These symptoms closely resemble those caused by iron deficiency and they can be alleviated specifically by applying sprays containing iron. Characteristic metabolic changes occur in the leaves of plants showing lime-induced chlorosis1–3, and the bicarbonate ion has often been suggested as a cause4,5. This type of chlorosis is known to affect root respiration as well as iron absorption and translocation6,7. The symptoms of the chlorosis caused by treatment with bicarbonate are closely similar to those of lime-induced chlorosis and various foliar changes are common to both.