Although calcium is abundant in the soil, there is not much calcium that can be absorbed and utilized by plants. This is mainly because the calcium that can be absorbed and utilized by plants depends on below two factors:
One depends on the absorption of plant roots. Plants can only absorb calcium from young root tips. Phosphorus and potassium uptake cover the entire root zone and due to their ionic radius close to that of hydrogen ions.
Therefore, the hydrogen ions released from the roots are preferentially exchanged with potassium ions, sodium ions, and ammonium ions, which will have a competitive inhibitory effect on the absorption of calcium ions, thereby affecting the absorption of calcium ions by roots.
The second depends on the ability of the plant’s aerial parts to transport calcium. After calcium uptake by plant roots, calcium migrates mainly from xylem into vigorously growing organs and tissues via transpirational flow.
When calcium reaches these tissues and organs, part of it is in the ion state, and the other part is insoluble calcium salt. Once calcium is deposited in certain tissues and organs, it is easily fixed and difficult to reuse.
Physiological Effects of Calcium
1.Stabilize Cell Wall
Plant cell walls are rich in calcium ion binding sites, and most of the calcium is linked to pectin in the cell wall. On the one hand, it maintains the structure of the cell wall, and on the other hand, it regulates membrane permeability and related physiological and biochemical processes.
Within the framework of cell wall carbohydrate and protein architecture, since calcium ions are integral components of the cell wall, the interaction between calcium and molecules contributes to the stability and expandability of the cell wall structure.
Following calcium deficiency, cell wall synthesis is blocked and cell division is inhibited in the meristem. At the same time, the breakdown of the cell wall caused by calcium deficiency makes the cells susceptible to infection by pathogens.
2.Participate in Information Transfer
When the signal reaches the cell, the plasma membrane instantly becomes more permeable to calcium ions. When the cytoplasmic Ca2+ concentration increases to a certain threshold, it associates with calmodulin (CAM) to form a Ca-CAM complex that activates CAM. This activated CAM can further activate various key enzymes in plants. Then the cells can undergo physiological responses corresponding to the signals, such as cell division, material synthesis, etc.
Effect of Calcium on Crop Yield &
As a medium and trace element, calcium can increase the yield of crops to a certain extent, and also plays an important role in the growth and development of crops themselves.
There is an experimental study of soaking sweet potato seedlings with calcium fertilizer solution, and the results show that the yield of sweet potato soaked with calcium fertilizer is nearly 2 times higher than that without soaking.
Calcium not only increases yield, but also plays an important role in crop quality. In the fruit tissue that maintains a high calcium level, the respiration rate is reduced, ethylene production is inhibited, protein synthesis is promoted, the impact of chilling injury is reduced, the fruit storage life is prolonged, calcium can keep the fruit firm for a long time, and the value of the commodity increases.
From another point of view, calcium can not only improve the starch, protein and Vc content of crops, but also improve the disease resistance of fruits and vegetables. The physiological diseases of many fruits have a very important relationship with the lack of calcium content in them.
In our experiment, on the basis of conventional fertilization, micronutrients were applied to potatoes during the growth and development period.
The results showed that calcium and magnesium fertilizers had the best effect on increasing potato yield. Compared with conventional fertilization without adding calcium fertilizer and magnesium fertilizer, the yield was increased by 10.2% and 9.2%. Many studies have shown that the application of trace elements can make the plants grow better, thereby increasing the yield of crops.