The effect of darkening on the susceptibility of plants to infection with viruses ii. Relation to changes in ascorbic acid content of french bean and tobacco

The ascorbic acid content of leaves of French bean and tobacco depends on age of the leaf and on illumination during the period immediately before harvest. There is a measurable diurnal fluctuation with the French bean. Ascorbic acid is lost within a few days from the leaves of intact plants or from detached leaves cultured in water in darkness, and from the darkened part of partly darkened leaves. The simultaneous increase in susceptibility of darkened leaves to infection by viruses was not reversed by infiltrated ascorbic acid.