Controlling Calcium mineral is delicate in the plant. A deficiency can cause problems such as blossom end rot in sweet pepper and tomato, burnt edges in leafy crops and ‘trip burn’ in some ornamental crops. The other way round, excess leads to gold spot on tomatoes and stip (color spotting) in peppers. Just paying attention to the nutrition is not enough. The distribution in the plant is crucial. This can be regulated but it requires a lot of diligence.
Even very experienced growers sometimes encounter problems due to a shortage of calcium. A typical situation for example is when a number of mature peppers have just been harvested in the greenhouse and the weather changes. Clear blue sky and a good temperature. Ideal growing weather, but this is just the situation in which blossom end rot persistently strikes. The leaves transpire heavily and draw the entire water flow from the xylem vessels in their direction. The young fruits receive sufficient water but not from the xylem. As a result, they remain devoid of calcium and blossom end rot occurs. In this situation, the grower has to pull out all the stops if he wants to avoid it.
Calcium is an unusual element in the plant. In addition to be a nutrient for the plant, it also acts in a similar way to a plant hormone within a cell. This latter property makes it more complicated to control than other minerals.
Controlling Calcium, Cement;
Calcium is essential for a cell to function properly. Within the cell walls the calcium bonds act like a sort of cement. A deficiency leads to soft tissue that can disintegrate. Furthermore, the mineral is important fr the cell membrane. This is a barrier through which the cell can take up active substances. When there is too little calcium, the membrane can leak and any substances can enter the cell. Very little calcium is present in the cytoplasm itself. Here the mineral acts as a messenger. Just a small change in the concentration sets off all kinds of processes, which is similar to the activity of a plant hormone. These processes can lead to degradation of the cell. In principle, this is a useful response by the plant because, for example, it prevents the further invasion of fungi or bacteria. If an infected cell dies off the fungi or bacteria cannot penetrate further.
In the case of blossom end rot, leaf burn or tip burn the cell membranes begin to leak. This is visible on the fruit or the leaf as the affected parts become translucent. Moisture from outside the cells flows inwards. This causes an excess of calcium that sets off a chain reaction. The useful response, in which the cells die off in an orderly way, spirals out of control and large amounts of cells die. Once this happens the dead cells dry off or start to rot.
Controlling Calcium, Irreversible Process;
The statement, prevention is better than cure, is particularly true here. If the damage is done, there is nothing left to do. The process is irreversible. First of all, of course sufficient calcium has to be present in the nutrient solution. The relationship between calcium, potassium, magnesium and ammonium is important. These minerals compete with each other during uptake by the root.
