It’s normal to think that if there’s a deficiency in the plant, it must be deficient in the nutrient solution. But that’s not always the case. Plant chemistry is a very complex process where each element affects others, as well as environmental conditions. Calcium is a major building block for plants, and like any other element, can become deficient in plants even when in plentiful supply in the nutrient solution. But a calcium deficiency is very difficult to diagnose because it has such a wide range of symptoms, and can simply look like other deficiencies and/or diseases.
Why Plants Need Calcium
Calcium is used in the plants cell walls during their formation, It’s basically required for the stability and function of the cell membrane, and it acts like a kind of glue or cement, binding the cell walls together. So if adequate calcium is not in the cell tissue during the formation of the cell walls, the plant tissues will simply be less stable and prone to breaking down. It then can look like a wide verity of symptoms of disease and/or deficiencies, that also makes the plant tissue more prone to getting disease and viruses from other environmental conditions and/or insects.
Once the cells are formed, the calcium is glued/cemented in place and becomes immobile. Because calcium has then become immobile within the plant, a constant supply of calcium is needed for healthy growth as the plant continues to grow. If there’s a lack of calcium supply within the plant, once the cells are already formed, they can’t be repaired by an increase of calcium supply to the cells that have already been formed. But the new plant growth can grow healthy and normal. When other elements are in excesses, calcium also helps act as a buffer for the root system. Calcium even plays a part in activating enzymes that regulate the flow of water movement within the plant cells, and is therefore vital for new cell growth and division.
Factors that Influence Calcium Availability
Plants have two basic types of tissues to transport the minerals and sugars they need for growth though the plant, the xylem and phloem. These act as the circulation system for the plant, like vain’s and blood vessels in a human. The xylem vessels carry water along with the dissolved nutrients from the roots up stems to the leaves and fruit. Water is lost from the foliage by transpiration (like exhaling in humans), through small pours in the stems and leaves called stoma. This creates a suction which draws up water from the roots through the xylem vessels, and distributed all around the plant.
Any condition that affects plant transpiration will affect the water flow/uptake through the xylem. Since the calcium is transported primarily through the xylem, this will affect the calcium nutrition of the plant. Slow uptake of water into the plant can lead to calcium deficiencies, even if there’s plenty of calcium in the nutrient solution. Therefor encouraging transpiration is one of the best ways to ensure the plant is getting the calcium it needs all the time. Environmental conditions like high humidity and little or no air flow, slow down transpiration of the plant. Adding ventilation is the simplest way to encourage plant transpiration. High temperatures and water stress also affect calcium intake. Keeping the plants stress free, with good ventilation, will go a long way to good calcium nutrition.
Also not all parts of the plant will transpire at the same rates. The tips and edges of new and/or fast growing foliage, as well as fruits tend to transpire at slower rates than the already established older foliage. Because of this, a calcium deficiency in the plant tissue can appear in the form of “Tip Burn” and/or “Blossom End Rot” (BER). But both Tip Burn, and Blossom End Rot can be caused by other things, making a calcium deficiency quite difficult to diagnose.
It’s also important to maintain a well balanced nutrient solution. Most all commercially made hydroponic nutrients are well balanced. Although as the plants take up nutrients from the nutrient solution, the balance tends to be thrown off. Another important factor to consider is the strength of the nutrient solution, nutrient solutions that are too strong can inhibit calcium uptake from the plants roots.