Development of “stem-topple” disorder in Ranunculus asiaticus is related to localised disturbances in tissue calcium levels

SUMMARYA variety of physiological disorders in plants are known to be induced by calcium deficiency, and display localised symptoms of necrosis, mostly in slowly transpiring organs or rapidly growing tissues. Flower “stem-topple”, identified in some geophytic plants, was suggested to be a calcium-related disorder. In Ranunculus asiaticus L., the zone susceptible to toppling is the growing section of the flower-stem. Since rapidly growing tissues use large amounts of calcium, and growth involves dilution of the cell contents by the deposition of water, a deficient supply of calcium may be induced locally in such tissues, even when the supply of calcium to the plant is sufficient. In the present study, to investigate the potential involvement of localised tissue calcium levels in the induction of “stem-topple” disorder in R. asiaticus, we attempted to correlate the occurrence of the disorder with the spatial distribution of minerals along the flower stem. Since the amount of N applied as fertiliser has been...