1. Nitrogen
Nitrogen accounts for 1-3% of plant dry matter. Nitrogen absorbed by plants is mainly inorganic nitrogen (NO-3, NO-2, NH+4), and sometimes simple organic nitrogen, such as urea (CO(NH2)2) and amino acids.
Nitrogen plays an important role in plant life activities because it is a component of many compounds; (1) genetic material-nucleic acid; (2) biocatalyst-enzyme; (3) substances that regulate enzyme activity-vitamins, auxiliary groups, coenzymes and hormones; (4) phospholipid, the skeleton of cell membrane; (5) Photoreceptors-chlorophyll and phytochrome; (6) Energy carriers-ADP, ATP, etc. ; (7) Permeable substances-proline and betaine.
When nitrogen is lacking, the old leaves first turn green and yellow, and sometimes purple appears on the stems, petioles or old leaves. When nitrogen deficiency is serious, leaves fall off and plants are short.
The metabolic feature of nitrogen in the body is that it can be moved and reused. When plants lack nitrogen, the nitrogen in old leaves is transferred to new tissues to meet the demand of tissues for nitrogen. Therefore, the symptoms of nitrogen deficiency are first manifested in the old leaves (the old leaves turn green and yellow).
2. Phosphorus
Phosphorus also plays a very important role in plant life activities. Plants mainly absorb phosphorus in the form of H2PO-4. It mainly absorbs H2PO-4 at low PH value and HPO2-at high PH value.
Phosphorus is also a component of many important compounds: (1) genetic material-nucleic acid; (2) the skeleton of the membrane-phospholipid; (3) enzyme activity regulators-phosphate cofactor and coenzyme (FAD, NAD, FMN, NADP, etc.). ) and vitamins; (4) Energy carriers-ATP, ADP, etc. ; (5) regulating substance transportation (sucrose phosphate); (6) adjust the PH value.
Symptoms of phosphorus deficiency: dark green leaves, reddish purple stems and leaves.
The metabolic characteristics of phosphorus in plants are mobile and reusable, so the symptoms of phosphorus deficiency are first manifested in old leaves.
3. Potassium
Potassium is also an important element in plants, the only monovalent metal ion among essential elements in the body, and it is ionic in the body. The main function of potassium in the body is to regulate: (1) regulating the opening and closing of stomata; (2) regulating root water absorption and water upward transportation (root pressure); (3) osmotic adjustment; (4) regulating enzyme activity-activators of many enzymes, such as glutathione synthetase, succinate CoA synthetase, starch synthase, succinate dehydrogenase, fructose kinase, pyruvate kinase and more than 60 kinds of enzymes; (5) Balanced electricity: in oxidative phosphorylation, K+ and Ca2+ as corresponding ions of H+ balance H+ charge, and in photosynthetic phosphorylation, K+ and Mg2+ as corresponding ions of H+ balance H+ charge; (6) Regulating substance transport (phloem contains a lot of K+).
The form of potassium deficiency: the tip and edge of leaves wither first, and then gradually zoom. Another main symptom: potassium is movable and reusable in the body, and the symptom of potassium deficiency first appears in the old leaves.
4. Sulfur
Plants mainly absorb sulfur in the form of SO42-. Sulfur is a component of many important compounds: 9 1) protein (sulfur-containing amino acids, cysteine, methionine); (2) Sulfur grease, a component of membrane; (3) Components of electron carrier -FD, Fe-S; ④ Vitamins (thiamine Vb 1, pantothenic acid VB3).
The main symptoms of sulfur deficiency: short plants, yellow leaves and easy to fall off. Sulfur is difficult to move in the body, so the symptoms of sulfur deficiency are first manifested in new leaves.
5. Calcium
Calcium is absorbed by plant ions (Ca2+). The main physiological functions of calcium are: (1) pectin calcium; (2) structural components-membrane and chromosome; (3) Activators of enzymes-ATP hydrolase and succinate dehydrogenase; (4) The second messenger is an important transmitter of intracellular information and regulates the activities of many enzymes alone or together with CaM; (5) Balance electricity: balance H+ (mitochondria) with K+.
Symptoms of calcium deficiency: necrosis of growing point, clumping of plants, yellowing of leaf tips and edges, scorching and necrosis. Ca is not easy to move in the body, and calcium deficiency symptoms are first manifested in leaves.
6. Magnesium (mg)
The main physiological functions of magnesium are: (1) chlorophyll; (2) As the corresponding ion of H+ in photophosphorylation, it balances electricity; (3) Activators of enzymes-Rubisco, PEPCase, etc. ; (4) Regulating protein synthesis (promoting the combination of ribosome size subunits).
Symptoms of magnesium deficiency: pulse green deficiency, sometimes reddish purple, magnesium can move in the body, magnesium deficiency symptoms first manifested in the old leaves.
7. Iron
Plants mainly absorb iron in the form of Fe2+ chelates. The main property of iron is valence change, Fe2+/Fe3+, so iron plays the role of electron carrier. (1) enzyme components-CAT, POD, cyanide oxidase, cytochrome oxidase; (2) Components of electron carriers, such as Fd, F-S, Cyt, etc. (3) The regulator of enzyme activity-a necessary factor of chlorophyll synthesis.
Symptoms of iron deficiency: the leaves are green between veins, and the whole leaves turn yellow and white in severe cases, so iron is not easy to move in the body. The symptoms of iron deficiency are first manifested in the elderly.
8. Copper
Plants absorb copper in the form of Cu2+. The main property of copper is that it can change the valence, Cu2+/Cu+. Its main function is as an electron carrier for redox reaction. (1) enzyme components-SOD ascorbic acid oxidase, polyphenol oxidase and cytochrome oxidase; (2) Electron transfer element -PC.
Symptoms of copper deficiency: the blade tip turns white and necrotic, and then develops along the vein to the leaf base, and the leaves are easy to fall off. Copper is not easy to move in the body, and the symptoms of copper deficiency are first manifested in the old leaves.
9. Zinc
The main physiological functions of zinc are the components of enzymes, such as tryptophan synthase and carbonic anhydrase.
Symptoms of zinc deficiency: green deficiency between veins, maize mosaic disease, fruit tree lobular disease, auxin synthesis blocked, and old leaves show symptoms first.
10. Manganese
Physiological effects of manganese: (1) oxygen releasing compound; (2) Activators of enzymes, such as phosphotransferase (hexokinase), dehydrogenase (α-ketoglutarate dehydrogenase), nitrate reductase and dipeptidase; (3) Elements of chlorophyll biosynthesis.
Symptoms of manganese deficiency: first there is green deficiency between pulses, then there is necrotic spot. Symptoms first appear on new leaves (not easy to move).
1 1. The main functions of boron are as follows: (1) It is related to the formation of reproductive organs, and the formation of tetrads of pollen mother cells is blocked when boron is lacking; Tapetum tissue is damaged and poorly developed; (2) Boron participates in the fertilization process, promoting pollen germination and pollen tube elongation; (3) Boron promotes the transport of sugar (forms a complex with sugar); (4) inhibiting the synthesis of CTK.
When boron is deficient, rape will not blossom and bear fruit, wheat ears will not bear fruit, cotton buds will not blossom, and brown spots will form inside the root tuber, such as beet heart rot. Radish brown heart disease.
12. molybdenum
Main physiological functions of molybdenum: nitrate reductase components.
Soilless culture is to raise plants with total nutrient solution.