The type and mechanism of herbicide

One type of herbicide

Classified by chemical structure, phenoxyacetic acid herbicides can be divided into categories, amide, diphenyl ethers, substituted urea, both triazine and pentachlorophenol sodium.

According to mode of action, herbicide selectivity and destroy nature can be divided into two categories. Selective herbicide, is selectively kill weeds without harming crops, a herbicide. For example ,2,4-D, 2 - A -4-- ammonia can kill dicotyledonous weeds, while cereal crops harmless; simazine can kill weeds in corn, while corn harmless; enemy barnyard grass barnyard can kill without harming the seedlings and so on.

Herbicide is also called non-selective herbicide. Such herbicides can kill all the plants the ground. For example, pentachlorophenol sodium and sodium arsenite, etc. in this category.

Pharmacy moved by the situation in plants can be divided into the absorption of herbicides contact toxicity of herbicides and herbicide. For example ,2,4-D, simazine, diuron and prometryn, etc. to the absorption of herbicides; nitrofen, pentachlorophenol sodium, etc. to contact toxicity of herbicides.

Second, the main mechanism of the herbicide and its

1. Phenoxyacetic acid class

Including 2,4-D, 2 - A -4-- chlorophenoxyacetic acid and their sodium salt, amine salt, which is an auxin herbicide at low concentrations, can promote the role of plant growth at high concentration that kills dicots, but little effect on monocots. Such pharmaceutical plants can promote the synthesis of nucleic acids and proteins, the cell division and elongation over, the organization was deformed due to excessive growth, thus preventing material transport, leading to plant death.

2. Amide

An amide propanil is a selective contact toxicity of the herbicide, the chemical name is N-(3,4 - dichlorophenyl) propanamide. Propanil is mainly used in addition to killing barnyard grass. Its role is to kill the grass in the destruction of photosynthetic electron transport of chloroplasts, the lack of barnyardgrass manufacturing organic nutrients; can damage leaf cells through the barnyard, so that water loss accelerated, wither and die. Propanil can not hurt rice, because rice plants exist in amide hydrolase, can cause decomposition of propanil.

3. Diphenyl ethers

There are nitrofen (2,4 - dichloro -4-- nitro diphenyl ether) and the grass dry ether (2,4,6 - trichloro -4-- nitro diphenyl ether). Contact toxicity of these herbicides is a herbicide that can be absorbed by plants, but not easy to transfer in plants can be killed except for some monocot weeds. The mechanism of ether toxic to plants is unclear.

4. Substituted urea

Including diuron, herbicides, Lung and so on. Such herbicides are the type of herbicide absorption. Cotton and carrots are resistant to such herbicides, because these crops have the decomposition of urea in vivo high activity of enzymes (such as N-demethylase enzymes). Such herbicides can inhibit plant photosynthesis, the plants die of starvation due to lack of nutrients.

5. Are Triazine

There are simazine, atrazine (atrazine), prometryn and so on. Such herbicides are the type of herbicide uptake and by inhibition of photosynthetic phosphorylation, NADP and the reduction of CO2 in the fixing process, failure of plant photosynthesis, the plants die of starvation, maize, sorghum and sugarcane for simazine and Atrazine has decomposition. Prometryn on cotton safety.

6. Pentachlorophenol sodium

This is a tag-based Herbicide. It is a respiratory inhibitor. Weed Control in rice is mainly used in the planting soil before the treatment. Effects of sodium pentachlorophenol respiratory chain oxidative phosphorylation, ATP can not produce, so that plants can not be normal breathing and death.