First. Conditions and necessary elements for plant growth
Discuss the elements required for plant growth from the composition of plants
1. What are essential elements (nutrients)?
There are nearly 60 different elements in plants. There are only 16 elements necessary for plant growth and development, which are carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, iron, manganese, zinc, copper, molybdenum, boron and chlorine. Without any of them, the growth and development of plants will not be normal, and each element cannot be substituted for each other or by elements with very similar chemical properties.
Numerous elements include: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium
Medium elements include: calcium, magnesium, sulfur
Trace elements include: boron, zinc, iron, copper, manganese, molybdenum, chlorine
No nitrogen, no growth, no phosphorus, no flower, no boron, no fruit, no potassium, no color, no calcium deficiency, more cracked fruit, no water, no tree, no light, no fruit.
Carbon, hydrogen, and oxygen come from the atmosphere and water, and the rest are absorbed from the soil by plant roots. There are many compound forms of each element, but the root system can only absorb the compound forms that it can use. For example, for nitrogen, most plants can only absorb ammonium nitrogen (NH4—N) and nitrate nitrogen (NO3— N), another example of phosphorus, the main form used by plants is orthophosphate (H3PO4). Therefore, it is very important to understand how plants absorb elements.
2. What are the characteristics of the necessary elements?
necessity, specificity, immediacy
3. Classification of essential elements required by plants
Macro elements: content > 0.1%
Medium elements: 0.01% < content < 0.1%
Trace elements: content < 0.01%
Second, the absorption of nutrients by plants:
(1) Minimum nutrient law - barrel effect
The minimum nutrient varies with time, place and crop growth period. The guiding significance of the minimum nutrient law for scientific and rational fertilization:
The nutrient demand of crops is not uniform, not the highest content of nutrients affects the yield, but the relatively least content of nutrients restricts the crop yield.
(2) The law of diminishing returns
The remuneration obtained from a certain land increases with the increase of the amount of labor and capital invested in the land, but with the increase of the input, the remuneration obtained by the unit of labor and capital decreases.
The guiding significance of the law of diminishing returns on scientific and rational fertilization:
The more fertilizers are applied, the better. Too much fertilizer is not only expensive, but also may cause fertilizer damage, affecting yields or failing to harvest.
(3) Nutrient return theory
As people grow crops on the land and take these products continuously, this will inevitably lead to a gradual decline in soil fertility, and the soil will contain less and less nutrients.
The guiding significance of nutrient return theory to scientific and rational fertilization:
In order to obtain continuous high and stable yields, it is necessary to supplement various nutrients required for crop growth and development in time.
(4) The law of equal importance
For crops, both macroelements and microelements are equally important and indispensable. Even if a certain microelement is lacking, although its required amount is very small, it will still affect a certain physiological function and lead to a decrease in yield.
The guiding significance of the law of equal importance to scientific and rational fertilization:
Various nutrients are equally important to crops, and trace elements, rare elements and macro elements are equally important.
(5) The law of irreplaceability
Each nutrient element required by crops has certain functions in the body of the crop and cannot be replaced with each other. If phosphorus deficiency cannot be replaced by nitrogen, potassium deficiency cannot be replaced by nitrogen and phosphorus. If any nutrient element is missing, it must be supplemented by applying fertilizer containing this element.
Fertilizer requirements and fertilization techniques of fruit trees:1. The characteristics of fertilizer need in life, 2. The characteristics of fertilizer need in one year
1. The characteristics and purpose of fertilization of fruit trees in their lifetime
2. How many times a year should fruit trees be fertilized?
The importance of applying fruit-picking fertilizer to fruit trees:
1. Restore the tree in time, and have sufficient nutrient accumulation in winter to improve cold resistance;
2. After the nutrition is supplemented, it can promote the good differentiation of flower buds, lay the foundation for improving the fruit setting rate next year, and lay the foundation for the germination of spring shoots next year;
3. The application of fruit picking fertilizer can prevent defoliation in winter, prolong the life of leaves, help to preserve flowers and fruits in the next year, reserve nutrients for flowering and fruiting in the coming year, and prevent large and small years.
3. Physiological functions of essential plant elements and diagnosis of phytonutrient deficiency
No nitrogen, no growth, no phosphorus, no flower, no boron, no fruit, no potassium, no color, no calcium deficiency, more cracked fruit, no water, no tree, no light, no fruit.
(1) Physiological functions of essential elements in plants and symptoms of deficiency
1. No nitrogen, no growth
Nitrogen is a component of many important organic compounds in plants and affects the metabolic process and growth and development of plants in many ways. For example, proteins, nucleic acids, chlorophyll, enzymes, vitamins, alkaloids and hormones all contain nitrogen. Among them, protein is the basic substance in the protoplasm of plant cells, and it is also the basis of plant life activities.
Without nitrogen, there is no life phenomenon in plants!
Nitrogen is a component of chlorophyll and a component of nucleic acid. Various biological enzymes in plants also contain nitrogen. Nitrogen is an integral part of the vitamin and energy system in plants, and has a very obvious impact on plant growth and development.
When nitrogen is sufficient, plants can synthesize more protein, promote cell division and growth, so the leaf area of plants grows rapidly, and more leaf area can be used for photosynthesis.
The demand for nitrogen is more before flowering and during the flowering period, and the demand for phosphorus is more from the inflorescence separation to the flowering period. The potassium requirement continued throughout the growing period, especially during the period from inflorescence separation to berry ripening.
Physiological role of nitrogen (N): Nitrogen is a component of nucleic acids, coenzymes, phospholipids, chlorophyll, cytochromes, plant hormones (CTK) and vitamins. It is a constituent element of proteins and nucleotides, and it participates in the formation of chlorophyll and improves photosynthesis.
If the supply is too large, the crops will be greedy and late, and the growth period will be prolonged, mainly manifested in thin cell walls, soft plants, and susceptible to mechanical damage (lodging) and diseases (such as barley brown rust, wheat scab, rice brown spot). )
Symptoms of nitrogen deficiency in plants: slow growth, dwarf plants, yellowing and scorching of old leaves, pale green new leaves, and early maturity.
Nitrogen fertilizers mainly include: urea, ammonia, ammonium bicarbonate, ammonium sulfate, ammonium chloride, ammonium nitrate, etc.
2. It is difficult to flower without phosphorus
Phosphorus is a constituent element of many important compounds in plants. The composition of nucleic acids, nuclear proteins, phospholipids, phytochemicals and high-energy phosphoric acid compounds all contain phosphorus, and phosphorus is actively involved in various metabolisms in the body.
Phosphorus can also improve plant stress resistance and adaptability to the external environment: improve plant drought resistance, cold resistance, pest resistance, lodging resistance and adaptability.
Phosphorus also exists in various dehydrogenases, flavinases, aminotransferases and other enzymes. They are important catalysts in many metabolic processes in crops, which are conducive to the smooth progress of various metabolisms.
Phosphorus is a constituent element of important compounds in plants, an important main component in nuclear proteins that make up the nucleus and protoplasm, and is a substance required for normal cell division, energy metabolism and heredity.
It plays a particularly important role in the life processes of plant ontogeny, growth, reproduction, inheritance and variation. Phosphorus is a key element that determines the differentiation of flower buds and the development of pollen, and is an element required for reproductive growth and vegetative growth.
When the crop is deficient in phosphorus, it is manifested as slow growth, reduced yield, reduced flower bud differentiation, fewer flower buds, and more "false flowers", which seriously affects the number and yield of fruits.
Phosphorus actively participates in various metabolisms in the body: it participates in carbohydrate metabolism, promotes nitrogen metabolism, and is closely related to fat metabolism; superphosphate does not contain impurities such as calcium sulfate, which greatly increases the content of phosphorus and becomes a high-concentration phosphate fertilizer. Therefore, the problem of sulfur deficiency will naturally occur with the application of superphosphate all the year round.
Physiological role of phosphorus (P): Phosphorus plays an important role in cell division and flowering. It has a good effect on improving stress resistance (disease resistance, cold resistance and drought resistance). Promote root development, especially lateral and fine root growth. Accelerates flower bud differentiation, early flowering and maturation.
Phosphorus deficiency symptoms in plants: The growth and development of the plants are hindered, the branches are few and dwarfed, the leaves appear dark green or purple-red spots, and the stems are purple-red and lose their luster.
Phosphate fertilizers mainly include: ammonium dihydrogen phosphate, potassium dihydrogen phosphate, superphosphate and so on.
3. No potassium, no coloring
Potassium is the main nutrient element for plants and one of the three factors that often affect crop yield due to insufficient supply in the soil. Crops contain potassium similar to nitrogen and higher than phosphorus. And in many high-yielding crops, potassium content exceeds nitrogen content.
Unlike nitrogen and phosphorus, potassium is not a component of organic compounds in plants. The main function of potassium is to participate in the metabolism of plants, such as promoting photosynthesis and the transfer of photosynthetic products, regulating ion and water balance, promoting protein metabolism, enhancing plant stress resistance, regulating enzymes and stomata in plants, and promoting protein synthesis and transportation.
Potassium makes the protein produced by photosynthesis stored and transported to fruits and seeds, and participates in the transport of photosynthetic products. The pulp of the potassium-deficient fruit is not full, the fruit is deformed, the hardness is small, the weight is light, the color is poor, and there is no brightness.
Potassium contributes to crop stress resistance: One of the important physiological roles of potassium is to enhance cellular regulation of environmental conditions. Potassium can enhance the tolerance of plants to various adverse conditions, such as drought, low temperature, salt content, pest damage, lodging, etc.
Although potassium fertilizer has many benefits, the more the dosage is, the better. Excessive application will bring adverse effects on crops:
● The absorption of magnesium and calcium by crops decreases, causing the occurrence of various diseases such as "rotten heart disease" of leafy vegetables and "bitter pox" of apples;
● It hinders the growth of crops, which makes crops prone to lodging and other symptoms
● Causes harmful metals and harmful bacteria to exceed the standard in some plots, destroys the nutrient structure and balance in the soil, leads to deterioration of soil properties, and water pollution;
● It will reduce the production of crops, seriously weaken the production capacity of crops, and reduce the output.
The common symptoms of potassium deficiency in plants are burns along the leaf margin, starting from the lower old leaves and gradually expanding to the upper leaves; potassium-deficient plants grow slowly and have poor root development; stems are fragile and often lodging; seeds and fruits are small And dry and wrinkled; plant resistance to disease is low.
Physiological role of potassium (K): the content of potassium (K) in plants exceeds P, and in high-yield crops it also exceeds N. It mainly exists in an ionic state. It is an activator of many enzymes (more than 60 kinds) in organisms and an important component of cell osmotic potential. component, regulates the opening and closing of stomata, promotes photophosphorylation, and facilitates the transport of assimilates.
Symptoms of potassium deficiency in plants: leaf tips or leaf margins turn yellow, brown, scorched like burning, brown spots or plaques appear on the leaves, but the vicinity of the main vein is still green.
Potassium fertilizers mainly include: potassium sulfate, potassium chloride, potassium nitrate, potassium dihydrogen phosphate, plant ash, potassium feldspar, etc.
4. There are many black spots in the cracked fruit due to calcium deficiency
Calcium is a nutrient element required for plant growth and has a variety of physiological functions. As an intracellular two messenger, it participates in various physiological processes of crop growth and metabolism, plays an important role in maintaining the normal life activities of cells, and affects crops in many ways. Growth and development of fruit quality.
Calcium is not easy to transfer in the plant. When calcium is deficient, young leaves first show symptoms of dehydration and yellowing, and then dry and turn brown; fruit lesions appear on the fruit surface, which are water-soaked dark green at the beginning, and gradually develop into dark green or dark green. Grayish-white depressions, brown spots and no rot after maturity, this is the navel rot fruit that planting friends often say.
Calcium has a variety of physiological functions in crops, which can stabilize cell membranes, cell walls, and promote cell and root growth.
Symptoms of calcium deficiency in plants: apical buds, lateral buds, root tips and other meristems are prone to rot and death, leaf tips are hook-shaped and stick to each other, dry heartburn, tendon rot, umbilical rot, etc.
Therefore, in the middle and late stages of fruit expansion, or before bagging, the fruit will be meticulously sprayed with Haifanwo chelated calcium fertilizer for foliar spray supplementation. Generally, the fruits that are supplemented with calcium fertilizer by foliar spraying have few cracked fruits, soft fruits and diseased fruits.
Physiological role of calcium (Ca): Calcium is a component of pectin calcium in the intercellular layer of the cell wall; it is related to cell division; it stabilizes the function of biofilm; it can be combined with organic acids as insoluble calcium salts to relieve the accumulation of organic acids. hazard; activator of a few enzymes.
Symptoms of calcium deficiency in plants: apical buds, lateral buds, root tips and other meristems are prone to rot and death, leaf tips are hooked and stick to each other, dry heartburn, tendon rot, umbilical rot, etc.
Calcium fertilizers mainly include: calcium ammonium nitrate, calcium nitrate, calcium chloride, EDTA chelated calcium, sugar alcohol complex calcium, etc.
5. It is difficult to set fruit without boron
Promote pollen formation: Boron promotes pollen formation and pollen tube germination in plants, reduces wheat flowers without fruit, cotton buds without flowers and pollen deformities, and avoids flowers and buds falling off easily, fertilization is abnormal, fruit seeds are not full, etc. .
Boron promotes cell elongation and cell division, and is an important element in the growth and development of plant reproductive organs. It can directly promote the formation of reproductive organs, promote the elongation of pollen tubes, and directly affect the pollination and fertilization of flowers.
Promote cell elongation and tissue differentiation: Boron can promote crop cell elongation and cell division in plants, which is beneficial to the growth and elongation of crop roots, avoiding growth point necrosis, leaf deformity, thickening, pericarp cortex, beet heart rot etc.
Promote carbohydrate transportation and protein metabolism: Boron participates in the transportation and metabolism of carbohydrates in crops in plants, increases the sugar content of crop fruits, improves fruit setting rate, and avoids stunted fruit development, deformity, and fruit drop.
Borax has poor solubility and needs to be dissolved in hot water at 40°C. The borax solution is alkaline, so it is inconvenient to mix with other pesticides and fertilizers. The cost is higher. Therefore, regarding the foliar spraying of boron fertilizer, we recommend Haifanwo chelated boron fertilizer, which can improve the seed setting rate and fruit setting rate and reduce deformed fruit.
Plants' demand for boron is particularly critical. Although the demand is not large, boron deficiency may cause symptoms such as unreal flowers, buds but not flowers, and even serious yield reduction. The bud stage, the early stage of flowering, and after 80% of the flowers are withered, it is the best time to use boron fertilizer, especially in the bud stage, the effect of spraying boron fertilizer on the leaves is especially good!
Physiological effects of boron (B): Boron affects the development of reproductive organs, affects the elongation and division of cells in crops, and plays an important role in flowering and fruiting.
Symptoms of boron deficiency in plants: the top stops growing and gradually dies, the root system is underdeveloped, the leaves turn green, the leaves are hypertrophic, shrinking, the plants are dwarfed, the stems and petioles are easy to crack, brittle and thick, the flowers are not fully developed, the flowers are not solid, Buds fall off easily.
The main boron fertilizers are: borax, boric acid, sodium octaborate tetrahydrate, fluid boron, boron magnesium fertilizer, etc.
6. Physiological role of iron (Fe): It is an important component of cytochrome, heme, ferredoxin and various enzymes. It plays the role of transferring electrons in plants and is an indispensable substance in the synthesis of chlorophyll.
Symptoms of iron deficiency in plants: It is not easy to move in the plant, and iron deficiency is first manifested on young leaves. It is manifested as chlorosis between veins, and the whole young leaves are yellowish-white in severe cases. Iron deficiency often occurs in high PH soils.
7. Physiological function of zinc (Zn): It is a component and activator of various enzymes. It has been found that more than 80 kinds of zinc-containing enzymes are involved in the synthesis of auxin.
Symptoms of zinc deficiency in plants: When zinc deficiency occurs in old tissues first, the auxin content decreases, the plant growth is blocked, the internodes are shortened, and the leaf expansion is inhibited. Zinc deficiency in corn appears white streak disease.
8. Physiological function of magnesium (Mg): It is an important component of chlorophyll, an activator of various enzymes, and plays an important role in photosynthesis.
Symptoms of Magnesium Deficiency in Plants: Mg is easy to move in plants, and symptoms first appear in old leaves when magnesium is deficient. In old leaves, intervein chlorosis occurs, and the leaf veins remain green, forming clear green reticulated veins (striped chlorosis between veins in Poaceae), and later the chlorotic part changes from light green to yellow or white.
9. Physiological effects of manganese (Mn): Manganese is a component of chloroplasts, which promotes seed development and early seedling growth, and plays an important role in photosynthesis and protein formation.
Symptoms of plant manganese deficiency: Symptoms start from new leaves, chlorosis between leaf veins, leaf veins are still green, brown or gray spots appear on the leaves, and gradually connect into strips, and in severe cases, the leaves become chlorotic and necrotic.
10. Physiological role of molybdenum (Mo): It is an essential element with the least requirement. MoO42- is a component of nitrate reductase and nitrogenase; it is a component of xanthine dehydrogenase and some oxidases in the synthesis of abscisic acid. Molybdenum is especially required for nitrogen fixation by legume rhizobia, and nitrogenase is composed of ferritin and iron molybdenum protein.
Plant Molybdenum Deficiency Symptoms: New leaves are deformed and spotted. spread on the leaves. Poor growth, short plants, and lack of molybdenum in legumes will affect nitrogen fixation, and the pods will not be full.
(2) Different demands of chlorine-loving, chlorine-tolerant and chlorine-avoiding crops for chlorine
Chlorine-loving crops - onions, spinach, celery, kale, etc.
Chlorine tolerant crops - rice, wheat, barley, corn, etc.
Chlorine-free crops - tobacco, potatoes, sweet potatoes, watermelons, sugar beets, etc.
Scientific fertilizer: chlorine-containing fertilizers should first be promoted on chlorine-loving and chlorine-tolerant crops.
(3) The special effects of rare elements on the growth and development of crops
1. What are rare earth elements?
Rare earth elements are the general term for the group of rare earth elements in the lanthanide series, including scandium Sc, yttrium Y and lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, europium Eu, gadolinium Gd, terbium in the lanthanide series Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, lutetium Lu, a total of 17 elements.
2. What are the effects of rare earth elements on the growth and development of crops?
Improve quality, promote roots and seedlings, increase yield, and enhance resistance
