Mobilization of calcium in glasshouse tomato plants by localized scorching.

It is postulated here that significant amounts of calcium will be mobilized into the plant by the scorching of one old leaf. This postulate was tested using large (6 m) tomato plants in the glasshouse. Brief scorching with a blowlamp was shown to release some 35% of the leaf's water into the plant. A range of measurements was used to estimate the kinetics and magnitude of this flow. The flow was found to carry a pulse of up to 50% of the leaf's total calcium into the plant, probably via the xylem, and was estimated to increase xylem calcium levels transiently by a factor of about 80. The potential value of scorching treatments in combating calcium-deficiency disorders is discussed.