A brief discussion on the scientific fertilizer of Cymbidium in summer

Summer is a very important season for scientific orchid cultivation, which is related to whether the physiological demise of old plants can be minimized, whether the new generation of seedlings can thrive, and whether they can accumulate material and physiological basis for autumn flower buds. The scientific use of fertilizer is an important link in the scientific cultivation of orchids. This paper talks about some experience in the scientific use of fertilizer in summer.

First, it is necessary to master the principle of scientific use of fertilizer.

(1) the use of fertilizer in summer should adhere to "equal emphasis on nitrogen and phosphorus"

Nitrogen is the "life element" of plant cell protoplast formation and metabolic process, and phosphorus is the "essential element" of plant cell division and growth, especially for promoting root growth. Nitrogen and phosphorus play a very important role in the growth and development of Cymbidium.

In early summer, the cold air in early spring in the south of the Yangtze River gradually recedes, Rain Water is abundant, and the temperature is pleasant, which is a good time for the young buds of Cymbidium to be unearthed, new roots to emerge, and tender leaves to spread. At this time, the center of the growth and development of Cymbidium has focused on the growth and development of new seedlings and roots. The growth and development of seedlings and new roots is completed by a large number of cell protoplast formation and cell division. Therefore, there should be enough nitrogen and phosphorus to meet the needs of the growth and development of Cymbidium. If it can not meet its needs, Huilan will implement self-regulation in the body, transferring nutrients from the old plant to its offspring, in order to achieve the purpose of replacing the new and the old and reproducing. After nutrition transfer, the leaves of the old plant start from the leaf tip, from the top to the bottom, from the periphery of the plant to the inside of the plant, gradually turn yellow and die. New seedlings developed in the case of lack of fertilizer are often relatively weak and unable to grow into big seedlings. Therefore, fertilization in summer must be based on nitrogen and phosphorus elements to meet the needs of the growth and development of new seedlings and roots.

(2) it is necessary to increase the application of potash fertilizer in July. The increase of potash fertilizer is not the usual use of potash fertilizer, but the proportion of potash fertilizer.

Potassium mainly exists in the body of Cymbidium in ionic state. Unlike nitrogen and phosphorus, potassium does not participate in the composition of important organic matter in Cymbidium. But potassium activates many enzymes in the body. It plays an important role in increasing the content of lignin and cellulose and enhancing the toughness of leaves and stems. It plays a significant role in the reproductive growth centered on flowering and fruiting.

July is the extension period of the leaves of Cymbidium. Because the leaves of Huilan are banded, some of them are more than 50 centimeters long. In order to keep the leaves tough, straight and graceful, July is a basic period. Only by increasing the application rate of potash fertilizer in July, increasing the content of lignin and cellulose in Cymbidium during the leaf extension period, thickening the cell wall of leaves and having a developed mechanical tissue, can the inherent characteristics of Huilan leaves be reflected.

July is an important period for Huilan's vigorous vegetative growth and reproductive growth. From July, the buds of Cymbidium will begin to differentiate and gestate, and the buds are generally differentiated and gestated on the robust plants of last year. Whether the buds can differentiate and gestate requires not only enough nitrogen and phosphorus, but also sufficient potassium to ensure. Therefore, the application of potash fertilizer in July is an important measure to ensure the differentiation of pregnant buds and fragrance in mid-spring in the coming year.

Second, we should pay attention to the method of applying thin fertilizer frequently.

Thin fertilizer, that is, the fertilizer should be dissolved and diluted in proportion to sufficient water. To apply fertilizer frequently is to apply fertilizer many times in a certain period of time.

(1) the general principle of absorption of fertilizer by Cymbidium

Fertilizers can be divided into two types, one is a variety of synthetic inorganic fertilizers, such as urea, compound fertilizer, potassium dihydrogen phosphate, Huabao and so on, these inorganic fertilizers, referred to as inorganic salts. The other is organic fertilizer, such as cow dung, vegetable cake, bean cake and so on. The inorganic fertilizer in the donor soil (matrix) must be dissolved in water to become an ion before it can be absorbed by the root. The organic fertilizer in the donor soil (matrix) must be decomposed into simple inorganic matter by microorganisms and dissolved before it can be absorbed by the root.

How do roots absorb inorganic salts from the soil (matrix)?

The absorption of inorganic salt in the root of Cymbidium is at the uncorked root tip, which is an active physiological process, which is mainly carried out through ion exchange, usually through soil (matrix) solution, that is, the root itself produces a kind of root pressure, which makes the ions in the root exchange with the ions dissolved in the soil. The ions of inorganic salts are adsorbed on the protoplast surface of the root cells. This is the first step. Therefore, the key to ion exchange (that is, fertilizer absorption) is whether the concentration of cell sap in the root is consistent with that in the soil. If the concentration of fertilizer is higher than the concentration of root cell fluid, the water in the root will flow to the fertilizer, and the fertilizer will not only be unable to absorb, but also cause root injury. Under the condition of pot culture and coarse-grained substrate cultivation, the water content of the substrate in the basin is often insufficient, therefore, diluting fertilizer with sufficient water is an important prerequisite to ensure that Cymbidium can absorb fertilizer smoothly without injuring its roots.

The second step of the general principle of absorbing inorganic salts in the roots of Cymbidium is that once the ions outside the roots enter the human root cells, their main destination is to pass through a series of living cells in the roots, and finally into the human catheter. along with the water in the catheter, it is transported to the pseudobulb, and then to the chlorophyll in the leaves, which is the main organ of the aboveground part, and photosynthesis is carried out with water and carbon dioxide under the action of sunlight. Then the organic matter produced by photosynthesis is transferred and distributed to the most needed growth centers and other parts through the sieve tube.

(2) the relationship between internal and external factors and frequent application of thin fertilizer.

From the perspective of internal factors, the plant growth of Cymbidium is relatively tall (compared with Chunlan and Qiulan), but the pseudobulb is much smaller than Chunlan and Qiulan, because the pseudobulb is a warehouse for storing nutrients and water, and the pseudobulb is small, that is, less storage. Under wild conditions, the root system of Cymbidium is well developed, which can make up for the deficiency of small false bulb and small storage, and rely on the developed root group and strong underground absorption capacity to meet the growth needs of the aboveground part. However, under the condition of artificial cultivation, due to the limitation of pot capacity, the developed root group advantages of Cymbidium can not be brought into full play, and the nutrients absorbed by the roots are often unable to meet the needs of the growth and development of the aboveground parts. it must be satisfied by replenishing various elements many times.

From the perspective of external factors, at present, the majority of Lanyou plant Cymbidium only from the perspective of permeability, and most of them use coarse-grained matrix, such as yellow brick, volcanic stone, fairy soil and so on. The fertilizer retention performance of these substrates is poor, and the fertilizer they can release is very limited. The frequent application of thin fertilizer can make up for the poor fertilizer retention performance of the coarse-grained matrix, make up for the lack of nutrients in the matrix itself, and ensure the needs of normal growth and development.

Third, it is necessary to take more "shortcuts" of topdressing.

Extra-root topdressing is a fertilization method in which fertilizer is mixed into a certain concentration, sprayed on the leaves and entered into the inside of the leaves through the stomata and stratum corneum. The advantage of this method is that it can save the amount of fertilizer, can be combined with water spraying or spraying alone at any time, and can achieve the goal of labor saving, cost saving and quick effect.

The use of extra-root topdressing is a fertilization method which is different from soil fertilization and similar to intravenous injection of animals. it can greatly shorten the transportation distance of nutrients and exert fertilizer effect in a short time. Extra-root topdressing for Huilan, as long as the stomata of the leaves can be opened, fertilizer and water can directly enter the chlorophyll from the stomata of the leaves, and as long as there is sunlight, they can immediately enter the process of photosynthesis.

Extra-root topdressing is generally not limited by the variety of fertilizer (refers to inorganic fertilizer). We should start from each growth center, pay attention to the scientific collocation of various elements, strictly control the proportion of water, rather thin than thick, eat less and eat more. The next day after each extra-root topdressing, water should be sprayed on the leaves, which can not only improve the fertilizer efficiency, but also keep the leaves clean and open the stomata freely.

The author of this article is Wu Zongbin, director of Wenling Agriculture and Forestry Bureau, director of Wenling Agriculture and Rural work Office.