| Biochar has attracted more and more attention in the research and application.It has been regarded as a new type of important soil improvement material.The addition of biochar to soil can effectively improve its physical and chemical properties and soil microbial environmental conditions,thus improving crop yield.One of the important abiotic factors affecting maize yield during drought,it is of great significance to clarify the response mechanism of applying biochar and nitrogen fertilizer to maize drought tolerance under drought conditions.In order to improve drought tolerance and crop yield of maize,this study set different biochar(0,8,16,24t/hm2)and nitrogen fertilizer dosage(0,150,300kg/hm2)through two years of biochar location test to explore its influence on drought tolerance of maize,soil physical and chemical properties and maize yield.The main research results are as follows:(1)The addition of biochar to the soil can effectively improve the soil structure,and the most significant change is the decrease of soil bulk density and the increase of soil porosity.In addition,the appropriate amount of biochar can increase the water content of surface soil.The combined application of biochar and nitrogen fertilizer can obviously improve the utilization efficiency of crops to soil water.The value of C8N150 was the highest,and the water use efficiency of biochar was 16.91%higher than that of the control.(2)The Superoxide Dismutase(SOD),Peroxidase(POD)is a reliable biochemical index for drought resistance after drought stress analysis,after drought stress,the activity of protective enzyme significantly increased,and biochar on the two kinds of protective enzyme were showed with the increase of carbon content,the active all showed a trend of decrease after the first increase and suggests certain applying biochar content can improve the activity of SOD,POD,and thus alleviate the membrane lipid peroxidation,improve the drought resistance;Malondialdehyde(MDA)content directly reflects the degree of damage to the cytoplasmic membrane,which is aggravated by the large accumulation under drought stress,while the application of biochar can effectively reduce the content of MDA,alleviate the damage caused by drought stress to plants,and further improve the drought tolerance of maize.(3)Biochar had a certain promoting effect on plant biological characters.Compared with the control,when the amount of biochar was 8t/hm2,the plant height and stem diameter of maize during silking increased by 8.17%and 10%,respectively,compared with that of the control.A reasonable amount of biochar had a certain promoting effect on the growth and development of maize,thus improving crop yield.When 8t/hm2 biochar was combined with 150kg/hm2 nitrogen fertilizer,the yield was increased.Compared with the control,the yield under normal irrigation increased by 12.81%.The yield increased by 11.79%after drought stress.To sum up,8t/hm2 biochar combined with 150kg/hm2 nitrogen fertilizer in soil is a suitable choice to promote plant growth and development and increase crop yield.(4)After drought stress,the dry matter accumulation and grain theoretical yield of maize at the silking and ripening stages were significantly different.Drought stress reduced dry matter accumulation by 12.20%and grain yield by 2.70%.Under drought stress,the drought tolerance coefficient of yield without nitrogen application was 0.883.However,the drought-tolerance coefficient was 0.923 after adding 150kg/hm2 nitrogen fertilizer.The drought tolerance coefficient of nitrogen fertilizer increased by 300kg/hm2 was 0.869,indicating that appropriate nitrogen application could improve drought tolerance of plants.Under drought stress,nitrogen application had a significant effect on dry matter accumulation and water use efficiency improvement in the mature stage.Compared with no nitrogen application in photography,dry matter accumulation increased by 16.93%and water use efficiency increased by 13.29%. |
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