Iron ion is one of the most fixed elements in plants. It usually exists as a polymer compound with little fluidity. Iron in old leaves cannot be transferred to new tissues, so iron deficiency first appears in young leaves of plants. The leaves of iron-deficient plants will turn green, yellow and white, and the heart leaves are often albino, which is called chlorosis. In the initial stage, the veins fade but the veins are still green. Veins are deeper than mesophyll, and the color boundaries are clear. In severe cases, the leaves will turn yellow or even white. Dicotyledonous plants form reticular mosaic, while monocotyledonous plants form yellow-green striped mosaic. Symptoms of different crops are:
Woody tree species such as fruit trees are prone to iron deficiency. The leaves of new shoots lose green, yellow and white, which is called "yellow mosaic disease". The degree of chlorosis increases from bottom to top, and the incidence of summer and autumn shoots is more than that of spring shoots, and the diseased leaves are mostly in clear reticular mosaic, also known as "yellow mosaic disease". Brown spots, perforations, shrinkage, etc. It doesn't usually happen. If it is severely yellow and white, the leaf edge can also be burned, dried up and fall off early, forming dead branches or bald branches. If this situation is repeated several times, it can lead to the decline of the whole plant.
Flower ornamental crops are also prone to iron deficiency. The net pattern is clear and the color is beautiful, which can increase some ornamental value. Poinsettia lacks iron, its plants are short, its branches are clustered, and its top leaves turn yellow or white. Rose is short of iron, and the tender leaves at the top are yellow and white. In severe cases, the growing points and tender leaves are scorched. When chrysanthemum is seriously deficient in iron and loses its green color, the upper leaves are mostly brown, and the plant may partially die.
Leguminous crops such as soybeans are most prone to iron deficiency, because iron is a component of bean heme and nitrogenase. Iron deficiency will weaken the nitrogen fixation of rhizobia and make plants dwarf. When iron is deficient, the veins of the upper leaves turn yellow, and the veins remain green and slightly curled. In severe cases, all the new leaves turn yellow and white. When iron deficiency is extreme, many brown spots appear near the leaf edge, leading to necrosis.
Rice, wheat, corn and other cereal crops are short of iron, and the veins are green and striped. The closer the symptoms are, the heavier Harrison is. In severe cases, the heart leaves don't come out, the plants grow poorly, are short, grow slowly, and some even can't head.
Fruits, vegetables and leafy vegetables are short of iron, the terminal buds and new leaves are yellow and white, only green leaves are left along the veins, and the leaves are thinner, generally without browning and necrosis. Gray-yellow spots also appeared at the base of tomato leaves.
Woody plants are more sensitive to iron deficiency than herbs. Citrus, apple, peach, plum, cypress and mulberry in fruit tree economic forest; Cinnamomum camphora, Pterocarya stenoptera, Platanus acerifolia and Pinus elliottii in street trees; Corn, peanuts and sugar beet in field crops; Cauliflower, cabbage and water spinach in vegetable crops; Hydrangea, Gardenia and Rosa multiflora in ornamental plants are all sensitive to iron deficiency.
Other sensitive crops include berries, oranges, broad beans, flax, forage sorghum, pear trees, apricots, cherries, pecans, sorghum, grapes, mint, soybeans, Sudan grass, potatoes, spinach, tomatoes, cucumbers and walnuts.
Tolerance crops include rice, wheat, barley, millet, alfalfa, cotton, peas, leguminous grasses, grasses, oats, duck grass, beets and so on.
Some plants with high iron utilization rate tolerate and adapt to the biochemical reactions and changes of iron deficiency, which may be due to one or more of the following reasons: (1) The roots secrete hydrogen ions (H+); (2) Secreting various reducing compounds from the root system; (3) The reduction rate of Fe3+ to Fe2+ in roots is high; (4) Organic acids, especially citric acid, increased in root exudates; (5) transporting enough iron from the root system to the aboveground part; (6) Even if the phosphorus content in the growth medium is quite high, the accumulation of phosphorus in roots and stems and leaves is less.
In the actual diagnosis, when judging the iron deficiency of crops according to external symptoms, iron, manganese and zinc are easily confused, so it is necessary to pay attention to identification. Iron deficiency and manganese deficiency: the degree of iron deficiency and green loss is usually deep, the yellow-green boundary is often obvious, and there are generally no brown spots, while the degree of manganese deficiency and green loss is shallow, and brown spots or brown stripes often appear. Iron deficiency and zinc deficiency: zinc deficiency generally occurs in macular leaves, and iron deficiency generally turns the whole leaves yellow and white, with clear reticular patterns. How to prevent and control diseases and insect pests of grapevines in spring Before bleeding, that is, before the end of February, we should finish pruning the grapevines, remove moth-eaten branches, diseased branches and residual fruits, peel off the old warped skin, remove weeds and fallen leaves from the orchard, and take them outside the orchard for destruction. Spraying 1 5 Baume sulfur mixture in time can effectively control the occurrence and spread of diseases, inhibit overwintering eggs, and have obvious effect on pest control. From late February to early March, the hardened soil should be loosened quickly. When the soil is wet after rain, 200~300 times of organic liquid fertilizer can be sprayed to improve the soil, promote root fertilization and control the reproduction of harmful bacteria in the soil. Spraying 45% crystalline sulfur mixed solution or 0.3 Baume sulfur mixed solution 1 50 ~ 200 times solution after vines germinate. Knowledge of grape management Organic fertilizer is good for grapes.
Grape fertilization technology
Apply more organic fertilizer, improve soil fertility, improve soil conditions for grape growth, and lay a good foundation for sustained high yield and high quality.
I. Application of Nitrogen Fertilizer
Nitrogen is one of the nutrient elements that grapes need, and it absorbs about 0.3-0.6 kg of nitrogen per 100 kg of grape berries. Nitrogen fertilizer has a great influence on the growth and development of grapes. Proper application of more nitrogen fertilizer in a certain range can increase the number of branches and leaves of vines, enhance the tree potential of grapes, coordinate the vegetative growth and reproductive growth of trees, promote the germination of secondary branches, and play a role in flowering and fruiting many times and increasing production. However, if excessive nitrogen fertilizer is applied, the branches will grow slightly white, which will lead to a large number of fruit drop, reduce the yield, reduce the lignification degree of new branches and roots, and affect the overwintering ability.
Due to the loss of nutrients and the fixation of soil, some fertilizers can not be absorbed and utilized by roots. Therefore, in production, the annual nitrogen fertilizer application rate is generally 667 m2 12- 18kg. Fertilization should be based on base fertilizer, accounting for 40%-60% of the annual application. The best application time is immediately after fruit picking. At this time, the second growth peak of the root system has not ended, and the leaves have not fallen off. After application, some fertilizers can be absorbed by roots, participate in metabolism, produce and synthesize a large number of organic nutrients, increase the nutrient storage capacity of trees, and have obvious effects on restoring tree vitality and promoting flower bud differentiation. Topdressing is generally carried out in four stages: before germination, before flowering, after flowering and early coloring of berries. ① Topdressing nitrogen fertilizer before germination is mainly used to promote the development of branches, leaves and spikes and expand the leaf area of lianas, without applying base fertilizer. (2) For vines with more flower spikes, topdressing nitrogen fertilizer with a certain amount of phosphorus and potassium fertilizer before flowering can increase the number of spikes and reduce flower drop, and the dosage is about 1/5 of the annual application. ③ After flowering, when the fruit is the size of mung bean, topdressing nitrogen fertilizer can promote the fruit development and coordinate the growth of branches and leaves, and the dosage depends on the growth, and it should be less when the growth is vigorous; When the growth is poor, the application amount should be larger. Generally, it is110-1/5 of the annual application amount. (4) At the initial stage of fruit coloring, a small amount of nitrogen fertilizer combined with phosphorus and potassium fertilizer can be applied appropriately to promote the rapid growth and sugar content of berries, increase the color of fruits and improve the internal and external quality of fruits. The fertilizer is mainly phosphorus and potassium fertilizer, and the amount of nitrogen fertilizer is about110 of the annual application.
Second, the application of phosphorus and potassium fertilizer
Grape trees need less phosphorus, and generally need to absorb about 0. 1-0.3 kg of phosphorus per 100 kg of berries. Due to soil fixation and other factors, the utilization rate of phosphate fertilizer by vines is low, and the actual fertilizer consumption is higher than the above-mentioned amount. In general, the annual application rate of phosphate fertilizer in high-yield vineyards is 667m 2 10- 15kg of phosphorus pentoxide, which is equivalent to 70-10 of calcium superphosphate with a phosphorus content of 14%. Phosphate fertilizer is mainly used as base fertilizer, generally accounting for 60%-70% of the annual application. It should be applied as soon as possible after the fruit is harvested, because the second growth peak of grape root system is not over yet. After the applied phosphate fertilizer is absorbed by grapes, it participates in metabolism, produces a lot of organic nutrients, and increases the nutrient storage capacity of trees, which can not only restore tree vigor, promote flower bud differentiation, but also improve the frost resistance of grapes. The rest phosphate fertilizer is used as topdressing, and nitrogen and potassium fertilizers are applied at the early flowering stage, the early fruit growth stage and the early berry coloring stage, in which the amount of phosphate fertilizer applied at the early berry coloring stage should account for 65,438+0/5 of the annual phosphate fertilizer application, and the other two stages account for 65,438+0/65,438+00.
Grapes have a great demand for potassium, and the amount of potassium absorbed per 100 kg of grape berries is 0.3-0.65 kg. Adequate potassium supply can increase the sugar content of grapes and promote berry coloring. Generally, the application rate of potassium fertilizer in high-yield vineyards is 667m 2 15-22k g of potassium oxide, which is equivalent to 30-44kg of potassium sulfate with 50% potassium content. The application of potassium fertilizer is mainly based on base fertilizer, accounting for about 1/3 of the annual application. Topdressing is mainly in the early stage of berry coloring, accounting for 1/3 of the annual application, and topdressing accounts for about 1/6 in the other two periods. Pay attention to the application of nitrogen and phosphorus fertilizers.
Third, apply boron fertilizer and zinc fertilizer.
Eating boron fertilizer for grapes can improve the fruit setting rate, improve the nutritional status of grapes and increase the yield. When basal fertilizer is applied to boron-deficient soil in autumn, borax can be applied at the ratio of 0.5- 1.0 kg per 667m2 orchard. You can also spray 0.05%-0. 1% borax water solution before flowering.
When grape is deficient in zinc, the leaves become smaller, the internodes of new shoots become shorter, and a large number of seedless fruits are formed in the ear, and the yield decreases significantly. Methods to prevent zinc deficiency in grapes: Immediately after winter pruning, apply zinc sulfate solution with the concentration of 10% to the cut mouth; 0.2%-0.3% zinc sulfate solution can also be sprayed once before flowering and 3-5 weeks after flowering. Grapes with symptoms of zinc deficiency should be sprayed with 0.2%-0.3% zinc sulfate solution immediately, generally 2-3 times, and the time interval is 1-2 weeks.
In calcareous soil and other soils with less available iron, grapes are also prone to iron-deficiency leaf yellowing, which not only affects the growth of grapes, but also affects the yield and quality of grapes. Because ferrous sulfate is quickly transformed into a form that fruit trees can't absorb after being applied to the soil, the effect of applying ferrous sulfate alone is poor. The best method is to apply iron chelate, and Fe-EDDHA is more effective. But it's hard to buy and expensive. A more effective method is to mix ferrous sulfate with cake fertilizer (bean cake, peanut cake and cottonseed cake) and ammonium sulfate according to the weight ratio of 1: 4: 1 and then apply it to the soil layer with more capillary roots of grapes, and the effect is better before germination in spring. It is also possible to spray 0.3% ferrous sulfate and 0.5% urea aqueous solution during grape growth, but the validity period is short and it needs to be sprayed once every 1-2 weeks.
Fourth, the method and time of grape fertilization
It is best to apply base fertilizer immediately after grape picking. If it is not applied in time, it can also be applied during the dormant period of grapes. Fertilization is mainly based on organic fertilizer and phosphorus and potassium fertilizer, and a certain amount of nitrogen fertilizer is applied according to the tree potential (nitrogen fertilizer can be omitted if the tree potential is too strong, and more nitrogen fertilizer can be applied appropriately if the tree potential is weak). The application method of base fertilizer is to ditch along one side of vine, and be careful not to be too close to the tree, so as not to damage the roots too much and affect the growth of grapes.
Grapes need more nitrogen and potassium fertilizers, which need to be supplemented in time during the growth of grapes. When topdressing nitrogen and potassium fertilizers, they are generally applied in shallow ditches, and the fertilization time is in the bud expansion period, the initial flowering period, the period when the fruit is bean-sized after flowering, and the initial coloring period of grapes and berries.