THE CALCIUM SUPPLY OF FRUITS AND STORAGE TISSUES IN RELATION TO WATER TRANSPORT
As far as blossom-end rot is concerned it has become clear that it is correlated with the calcium supply of the plant (3,8). Not only the calcium status of the substrate but the K/Ca ratio also seems to be important. An important fact is that the fruits of the plant demonstrate a very low calcium content in comparison to stem and leaves (5) and that the acropetal part of the fruit (10), where the tissue necrosis occurs, is even poorer than the basal part.
Even under soil conditions conducive to the occurrence of this disease the incidence usually is very variable from grower to grower. Factors favouring manifestation of the disease can be high nitrogen supply (6, 12), insufficient soil moisture (4, 6) and glasshouse climate.
Taking the knowledge concerning transport in the plant into account it seems possible that some of these factors act by means of their influence on calcium distribution in the plant. The investigation to be reported was undertaken to elucidate the principles governing the calcium distribution in the plant and the reason for the poor supply of the fruits or other affected organs.