Rational use of drugs to prevent greenhouse vegetable pests and diseases
Spray parts should be accurate for the pests and diseases on the leaves to be sprayed on the front and back; for leaves and fruits on pests and diseases, spray leaves and fruit; for root diseases and pests, it is best to use irrigation methods.
The spraying time must be accurate The solar greenhouse vegetable production period is mostly in winter, so the spraying time is generally selected after the morning leaves dew dry and sprayed, if the continuous cloudy use of aerosol should be selected in the evening.
The dosage of the used pesticide should be accurate. If the concentration of the pesticide is too large or the concentration is too small, it is easy to make the vegetable not be a phytotoxicity or to effectively control the pest. Therefore, the dosage must be accurately used according to the effective content.
To understand the scope of use of commonly used pesticides, if the occurrence of bacterial diseases with fungicidal pesticide control is very poor. Bacterial diseases use bactericidal pesticides, fungal diseases use fungicidal pesticides. Is the so-called remedy.
To understand the principle of mixing pesticides in order to improve the control effect or expand the scope of control, in practical applications often need to mix two or more pesticides, but the mixed use of pesticides can not be used indiscriminately, be optimistic about the use of pesticides, otherwise it will reduce the drug Less effective than gains.
To change the large-capacity spray to low-volume spray low-volume spray technology can greatly increase the rate of pesticide deposition, give full play to the efficacy, and reduce environmental pollution.
According to the characteristics of vegetable varieties, the proper addition of adhesives such as green onion leaves, and the wax adhered on the surface of the pepper leaves are relatively smooth, so that the pesticides are not easily adhered to the leaves, so that the deposition rate of the pesticide on the leaves is greatly reduced, thereby affecting the control effect. Therefore, the adhesive can be properly added in practical applications.
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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