The key to managing photosynthesis is to maintain luxury levels of chlorophyll at all times. Photosynthesis takes place within individual chlorophyll units called chloroplasts. A loss of chloroplasts causes plants to become chlorotic (yellow). The more chloroplasts we can maintain in the plant, the higher the sugar production and the higher the yield potential. The chemistry of a molecule of chlorophyll is revealing.
A magnesium atom lies in the centre of the molecule, surrounded by four atoms of nitrogen plus the inevitable CHO (carbon, hydrogen and oxygen).
A chloroplast is nitrogen intensive and completely dependent upon magnesium, ie if the plant is not taking up luxury levels of magnesium into the leaf, then there will be some degree of chlorophyll deficiency. While the chemistry is remarkably simple, there is of course more to chlorophyll management than simply supplying enough magnesium and nitrogen. Sulphur is often tied to nitrogen performance, and a sulphur shortage will reduce the number of chloroplasts. The trace elements zinc, manganese and iron all play a role in the correct functioning of chloroplasts, and a shortage of any of these will create a corresponding drop in the number of chloroplasts.
Most growers are familiar with the chlorotic patterns associated with trace element deficiencies or the insipid pale of a crop running out of nitrogen puff, but the role of calcium in the supply of these chlorophyll builders to the leaf is often ignored. Calcium is the ‘trucker of all minerals’, and the presence of soluble calcium in the root-zone ensures the realisation of this transport potential.