The time of scientific control and control is generally 6~13 for corn, and the best for 8~13 leaves. Before the 6-leaf stage of corn, the leaves of the corn were slender and the leaves were smooth. When the corn is unfolded at the 7-leaf stage, it will become thick and thick, and fine white fur will appear on the leaf surface, which can be felt by the back of the hand. This is the best time to spray the chemical control agent. Spraying the drug is the first choice for the latest research results of the Chinese Academy of Agricultural Sciences.
The application of panicle and fertilizer to the ear nutrient has the highest absorption of mineral nutrients and the highest absorption intensity. It is the fastest period for corn to absorb nutrients and the most important fertilization period in life. The application of nitrogen fertilizer during the big bell period can effectively promote the differentiation of the florets of the ears and achieve more spikes and larger grains. Generally, 20 to 25 kg of urea or nitrogen-potassium compound fertilizer can be applied per acre. The topdressing method can be ditched on the row side or deep in the side of the plant. It is best to combine it with irrigation or during effective rainfall. It should not be applied on the surface of the soil to prevent fertilizer loss.
Strengthening pest control The pests and diseases in the summer maize ear stage should focus on the prevention and control of brown spot and corn borer. Brown spot disease can be controlled by 12.5% ​​straw or 12.5% ​​rusting foliar spray; corn mash can be filled with phoxim granules at the big bell stage or with 4.5% beta-cypermethrin emulsion or 50% phoxim emulsifiable concentrate Heart leaf spray is used for prevention and treatment.
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To extract a mixture of DNA fragments, put through a PCR instrument to do a simple purification. Remove the free fluorescent ddNTP single nucleotide, leaving a DNA fragment of a certain length, which can be sequenced on the machine. A polyacrylamide solution is first injected into a hollow capillary during the sequencing process. Then, the polyacrylamide solution was ionized by UV light irradiation to generate a polymerization reaction. The polyacrylamide gel produces a separation effect under the electric field to start the electrophoresis of nucleotide. The electrophoretic movement of short DNA fragments is fast, and the electrophoretic movement of long DNA fragments is slow. The mixture of DNA fragments moves from a negative charge to a positive charge under the action of an electric field in a capillary containing a polyacrylamide gel. The positive end of the capillary is irradiated with a solid-state laser, and a spectroscopic optical sensor records the different fluorescence intensities. Each DNA fragment, when passing through the laser scanning point, has a fluorescent group on it, which will emit a specific fluorescent color.
Because in the previous polymerization reaction process, the starting point of the polymerization reaction starts from a specific primer position. Therefore, the DNA fragment that reaches the laser scanning point of electrophoresis first is the shorter fragment, so its polymerization termination position will be closer to the polymerization start position. Therefore, the fluorescent color reflects which of the bases at its 3' end is A, T, C, and G.
Conversely, the slower the electrophoresis of DNA fragments reaches the laser scanning point, the longer the DNA fragments. As a result, its termination site is farther away from the starting position of the primer. Finally, a map of four colors is obtained.
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