Refining Method Of Wood Vinegar And Its Inhibition Effect On Barnyard Grass In Rice Field

Rice is the most important cash crop in China and the second largest grain crop in the world.In the process of rice production,field weeds are one of the main problems affecting rice planting and production.Among them,barnyard grass was defined as the most important malignant weeds in rice cultivation due to its strong diffusivity,drug resistance and stress resistance.The flood of barnyard grass will seriously affect the growth and yield of rice.At present,there are three ways of suppressing barnyard grass with high frequency in China: artificial weeding,mechanical weeding and chemical herbicide weeding.However,all three methods of weeding have many disadvantages.With the development of ecological agriculture technology,biological grass suppressants have been gradually applied to weed control in farmland due to their advantages of high efficiency,environmental protection and health.At present,the bioactive substances that have been found to regulate plant growth and have herbicidal effect mainly include acetic acid,some long-chain acids such as fatty acids,oils produced by plant processing,etc.,and wood vinegar liquor just contains these components.Wood vinegar is a kind of complex organic mixture produced in the process of high temperature distillation of wood.Wood vinegar is widely used in industry,agriculture,medical treatment,food and other fields.The original liquor of wood vinegar contains tar and other harmful substances,so it needs to be refined in many application fields before it can be put into use.In this paper,two refining methods of activated carbon adsorption(ACA)and reduced pressure distillation(RPD)were used to refine the wood vinegar liquor,and the removal effect of tar in the refined wood vinegar liquor was analyzed.The concentration changes of total acid,guaiacol and 5-nitroguaiacol sodium in wood vinegar liquor before and after refining were analyzed.The acid base distribution method was used to remove acid,aldehyde,ketone and phenol from wood vinegar liquor,which proved that wood vinegar liquor contained components that could regulate plant growth.The treatment of wood vinegar with different concentrations in pot and field experiments were given.This article obtained the following conclusions through experiments:(1)Both methods can effectively remove tar from wood vinegar.ACA method can significantly shorten the refining time of wood vinegar,but reduce the total acid concentration in wood vinegar.At 95?,the total acid concentration of the refined solution was the highest(33.1% higher than the original solution),and the conversion rate of 5-nitroguaiacol sodium was the highest(nearly 20 times higher than the original solution).(2)The effective concentration of wood vinegar on rice seed germination was 5‰,and the effective concentration of wood vinegar on barngrass seed germination was 2.5‰.(3)The main components that inhibit the growth of barnweeds in wood vinegar liquor are the acid substances in wood vinegar liquor,and the phenolic substances in wood vinegar liquor can improve the resistance of seeds.(4)At the concentration of 2.5‰-5‰,wood vinegar could not only ensure the normal growth of rice seedlings,but also inhibit the survival rate of barnyard grass seedlings,plant height,total chlorophyll content and accumulation of nutrients such as nitrogen,phosphorus and potassium.(5)At the tillering concentration of 1.25‰,2.5‰ and 5‰,wood vinegar had obvious inhibition effect on barnyard grass at the tillering stage,the inhibition rate of barnyard grass was 68.3%,85.0% and 87.4%,respectively.At the concentration of 2.5‰-5‰,wood vinegar liquor had a significant promoting effect on tillering of rice.Wood vinegar vacuole field did not affect rice plant height at tillering stage.Moreover,the concentration of 5‰ wood vinegar would not affect the yield and quality of rice.(6)The optimum concentration of wood vinegar used for barnyard grass inhibition in paddy field was 2.5‰-5‰ of the water stored in the field.