Prevention of elemental excess disease

(a) The excess of symptomatic elements mainly kills cells by destroying cell protoplasts and inhibits the absorption of other essential elements, causing damage to the crops causing sluggish growth, stiffness, and even death. Common symptoms include yellowing and whitening of leaves, brown spots, and marginal dry spots; malformations and distortions of stems and leaves; poor root elongation, bending, thickening, or death at the tip, increased branching, and abnormal roots such as lion tail and chicken feet. The part where the symptoms appear is due to the different mobility of the elements, and the part where the symptoms generally appear is the part where the element is easy to accumulate. This is exactly the opposite of elemental deficiency. Symptoms of yellowing appear in most of the excess disorders, which may be caused by elemental warts and inhibit the absorption of iron or manganese and zinc. Excessive amounts of manganese and copper significantly inhibit the absorption of iron. Many studies have shown that excessive amounts of manganese and copper sometimes occur with iron deficiency. Iron and zinc excessively inhibit the absorption of manganese. Nickel excess inhibits the absorption of zinc and manganese excessively suppresses molybdenum. Absorption is also more common, so the real cause of many elemental deficits is often the excess absorption of an element. The more common symptoms of excess (poisoning) are summarized below:

1. Manganese excess disease due to crops and there are large differences, but the majority of the performance of root browning, brown spots appear on the leaves, there are yellow leaves or purple-red leaves, fresh leaves and so on. Citrus Manganese excess caused by abnormal defoliation, the leaves appear red brown chocolate-like spots, especially chocolate spots; apple Mn excess caused by dermatophyte, excess Mn manganese leaf yellowing, high-section node birth, stem brown contaminants; The excess of manganese inhibits the absorption of molybdenum, and the lack of molybdenum on the acid soil may be caused by excessive manganese.

2. In the case of zinc excess disease, the young leaves of the plants showed chlorosis, yellowing, and the stalks, petioles, and lower leaves of the leaves were auburn. Excess zinc in rice, rice seedlings grow weak, leaves chlorosis; wheat excess zinc, brown spots on the tip; excess zinc in soybeans, leaves in particular the rib base is purple, leaf curling.

3. Most of the copper excess crops were yellowed and their root elongation was significantly impaired, and they did not fluctuate or form branches or roots. Rice copper poisoning, rice seedlings significantly yellow, stagnant growth; wheat copper surplus, darker body color, rigidity, lower leaves yellow, root disk. Excess copper significantly inhibits iron absorption, and sometimes crop excess copper appears as iron deficiency.

4. Excess molybdenum molybdenum crops, molybdenum, morphologically difficult to show, cotton plant molybdenum up to 15 mg / kg fertility without exception, but the feed crop contains molybdenum> 10 mg / kg, long-term feeding may cause livestock molybdenosis. Solanaceae crops are more sensitive to molybdenum excess, tomato, potato molybdenum excess, branchlets are golden yellow, red and yellow.

5. Excess nickel leaves lost chlorosis, brown necrosis appeared between veins, excess leaves of oats and nickel were chlorotic, white, and necrotic spots appeared.

6. Over-cadmium rice leaves and leaves sheath yellow brown. Cadmium contamination of food endangers human health. Long-term human consumption of cadmium-containing rice (or drinking cadmium-containing water, and eating cadmium-containing aquatic products) is prone to bone pain. Excess cadmium in leaves of wheat is dark brown; excess cadmium in soybeans, leaves are yellow, and veins are tan.

7. Boron excess boron moves in the plant along with the transpiration flow, water is lost along with transpiration and boron remains, and boron is concentrated at the tips and edges of the leaves. Therefore, excess boron is mainly expressed at the periphery of the leaves, mostly in yellow trim, and there are so-called vegetable crops. Phnom Penh; rice boron excess brown tip, dry roll, glume appeared brown (blight) spots; barley excess, leaves scattered a lot of tan spots.

8. Arsenic excess disease generally shows growth stagnation, yellow leaves, shedding, and root damage. Rice arsenic poisoning occurs yellowing on the shoots and leaves in the seedling stage. The leaves are reeled and gradually wither and die. The roots are light brown or tan. Local scald (or water immersion) occurs. The soft cotton loses its elasticity and is later exposed to organic arsenic ( Pesticides are poisonous and there are superimposed spikelets with overlapping glume; wheat has excess arsenic, dark green leaves, narrowing, hardening, and dead roots.

9. Overgrowth of mercury usually manifests as yellow leaves, short plants, depressed tillers, poor growth, poisoned by mercury vapor, and leaves and petals may be brown or black.

10. Excess sodium in excess of sodium In addition to inhibiting the absorption function of crop roots, it also affects crop carbon dioxide assimilation and protein synthesis, leading to physiological abnormalities in crops. The excess of sodium usually appears first in the old leaves. At the beginning, some tissues in the leaf margin form water immersion, followed by the formation of gangrene or withering. In severe cases, the extent of gangrene gradually expands to the center of the leaf. (b) Prone to environmental conditions The occurrence of elemental excess disease is generally caused by soil contamination, and the occurrence or absence of it depends mainly on the degree of soil contamination, but it is closely related to soil pH, Eh, organic matter (organic fertilizer application), and soil texture.

1. Soil pH The solubility of metal elements is related to the pH. When the pH is low, most of the metal elements such as copper, zinc, cadmium, nickel, aluminum, etc., dissolve out and the symptoms increase. On the contrary, the risk of molybdenum excess increases at high pH.

2. When the soil Eh is low at Eh, iron, manganese, and arsenic are aggravated, while elements such as copper, zinc, mercury, and lead are easily reduced due to the formation of sulfide precipitation.

3. Organic matter-rich soils can complex a variety of metal ions due to various organic acids, and their toxicity is reduced, which can alleviate or reduce the excess damage.

4. The soil has a viscous soil and a large cation exchange capacity. It has a buffer capacity for excess ions and can reduce the damage.

5. The climate is also related to excess disease, which usually increases the risk of increased temperature.

(3) Tolerance of crops to excess of elements There is a great difference in endurance of different crops that damages the excess of elements. For example, for endurance to aluminum, the sensitivity of barley to the root of the sensitive plant barley when the aluminum content of the medium reaches 1 mg/kg is impeded, while the concentration of aluminum in the old leaves of the tea tree reaches 30000 mg/kg. For example, tea trees are highly tolerant to aluminum and can accumulate aluminum to high concentrations. Harmless plants are called aluminum storage plants. On the existing information on the crop resistance mechanism, we can summarize the following aspects: (1) Inhibiting metal ions entering the root tissue, such as rice and grass reed rhizome that are resistant to low-valent iron (Fe2+) have the ability of releasing oxygen, so that the low-valent iron is oxidized Precipitate outside the roots without invading the roots. (2) Absorption and fixation of the cell wall. The zinc cell wall of Agrostis tenuis, which is known to be resistant to zinc, is sorbed with a large amount of zinc. (3) Metal ions have become stable and low-toxic compounds. Zinc, cadmium and organic complexes have been isolated from zinc-tolerant and cadmium-tolerant plants. At present, various metal-protein complexes have been found one after another in plants. One common view is that the presence of these complexes is related to the endurance of plants to metals. (4) Accumulation of metal ions in the vacuole. (5) Blocking transfer to the ground to protect the upper part of the ground. However, there are also institutions that promote the transfer to the earth and protect it. (6) Enzymes and cell granules have special resistance to metals.

(d) Overcapacity should focus on prevention. Specific measures include the following: 1. Control of pollution This is the fundamental measure for preventing and controlling elemental excess disease. It should formulate relevant laws and regulations to protect the farmland from pollution by three wastes. 2. Application of lime to lime, manganese, zinc, copper, nickel and other metal elements contaminated farmland, the application of lime, increase the pH, promote its oxidation and precipitation, reduce or eliminate the harm, the molybdenum poison should try to reduce the pH, acidification of the soil. 3. Reasonable irrigation and drainage of paddy soils are caused by the excess of chromium, cadmium, copper, zinc, mercury, lead, etc. The water layer is often maintained during rice growth to reduce the toxicity, and arsenic, iron, manganese, etc. should be drained and fielded to promote oxidation. Relieve harm. 4. Organic fertilizers are used to fix metal ions through complexation, adsorption, etc. to reduce poisoning. 5. When the application of inert elements such as zinc, iron excess, the application of high concentrations of phosphorus can inhibit its absorption. 6. Planting and accumulating plants can use such plants to absorb a large amount of special metal ions and accumulate specific metal ions. Repeated cultivation can gradually reduce the concentration of harmful metals.