Watermelon is generally divided into four main growth stages: seedling stage, flowering stage, flowering stage and maturity. Watermelon stems and leaves are luxuriant, the growth rate is fast, the fruit is large, and the yield is high. Therefore, it is a crop that requires more fertilizer, and it is necessary to supply sufficient fertilizer at an appropriate time. Nitrogen fertilizer can promote the growth of watermelon stems and leaves, and can increase the yield; phosphate fertilizer is beneficial to root growth, improve the cold resistance of seedlings, increase sugar content of fruits, promote early maturity and improve nitrogen nutrition; potassium fertilizer to improve plants The balance of nitrogen, phosphorus and potassium nutrients in the body has a good effect, and can promote the absorption of nitrogen by plants, and can also promote the synthesis of a large amount of sugar. Therefore, these fertilizers have a significant impact on the improvement of watermelon yield and quality. The absorption of nitrogen, phosphorus and potassium in the whole growth period of watermelon is the highest in potassium, followed by nitrogen and phosphorus. The characteristics of the absorption of fertilizer are: the amount of phosphorus absorbed from the vine season to the flowering period accounts for about 45% of the total phosphorus uptake, and the amount of phosphorus required is large. The amount of nitrogen required for the fruit expansion period is more than 78% of the total nitrogen requirement.
In response to these characteristics of watermelon, watermelon Shi Tianji brand of phosphorus nitrate (potassium) fertilizer should be combined with topdressing fertilizer and topdressing fertilizer. Generally, 30 kg of nitrophosphate is applied at the bottom, plus 8 kg of potassium sulphate or 35 kg of NPK. In the fruit expansion period, 25 kg of nitrophosphate and 8 kg of potassium sulphate or 30 kg of potassium pentoxide are applied. In addition, it should be noted that because watermelon is a chlorine-free crop, it must be applied with potassium sulfate when applying potassium fertilizer.
A polycrystalline novel silicate material obtained by crystallizing glass under the action of a catalyst or a nucleating agent, is a dense, nonporous, homogeneous mixture of a crystalline phase and a residual glass phase. Generally, the size of the crystal can range from nanometer to micrometer, and the number of crystals can reach 50% to 90%. Has high mechanical strength, low electrical conductivity, high dielectric constant, good machinability, chemical resistance, thermal stability and so on. These properties depend on the type and amount of crystals, as well as the composition and properties of the remaining glass phase, and are closely related to the crystallization conditions and the like. According to different nucleation or crystallization treatment, it is divided into photosensitive and heat-sensitive glass-ceramics. Can be used to make circuit boards, charge storage tubes, screens for photomultiplier tubes, missile warheads, radomes, bearings, pumps, reactor neutron absorbing materials, insulating pillars, etc.
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