Study On Measures And Physiological Mechanisms To Effectively Reduce Acetochlor And Atrazine Phytotoxicity To Dicotyledon Crops(Adzuki Bean,Pepper)

The irrational usage of chemical herbicides leads to various serious phytotoxicity,affecting the growth of crops and reducing yield.It will not only threat to global food security,but also destroy the balance of ecological environment.Adding naian,1g humic acid and 3g biochar can increase rate of emergence and production of crops via improving the antioxidant enzymes activities and photosynthesis,and acetochlor and atrazine resistance of crops.In this study,the influence of different mitigating substances（safener,fulvic acid,humic acid and biochar）,on growth,reactive oxygen species metabolism and photosynthesis of adzuki bean（Phaseolus angularis）and peppers（Capsicum annuum L.）plants were studied in pot culture and field culture under the residue of acetochlor and atrazine,which provides the measures and physiological mechanisms to effectively alleviate acetochlor and atrazine phytotoxicity to dicotyledon crops.The main results were following:（1）The results showed that herbicide acetochlor-atrazine stress significantly decreased rate of emergence,agronomic traits like plant height and fresh weight,chlorophy II a,chlorophy II b,total chlorophy II concentrations,maximum quantum efficiency of PSII photochemistry（Fv/Fm）,potential photochemical efficiency（Fv/Fo）,photosynthetic（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,intercellular CO₂concentration（Ci）,superoxide dismutase（SOD）activity,peroxidase（POD）activity,catalase（CAT）activity and production of crops.In contrast,leaf malondialdehyde（MDA）content and the residue of acetochlor and atrazine were higher than CK.These indicated that herbicide acetochlor-atrazine stress can influence the yield and quality of the crops.（2）After spraying herbicides,the residual amounts of acetochlor and atrazine in the soil will decrease with time,and prolonged time appropriately can reduce the occurrence of phytotoxicity.（3）In this experiment,different mitigating substances and different doses have different mitigating effects on different crops.In this test,measures to effectively alleviate acetochlor and atrazine damage to adzuki bean were to add naian,1g humic acid and 3g biochar,measures to effectively alleviate acetochlor and atrazine damage to pepper were to add 1g humic acid and 3g biochar.Adding naian,1g humic acid and3g biochar can effectively improve the emergence rate,yield and plant height of adzuki beans,for the pepper,adding 1g humic acid and 3g biochar can effectively improve the survival rate,yield and good for agronomic traits of mature too.Some measures like adding albit and 1g fulvic acid,the effects of reducing the phytotoxicity were poor,could not as effectively measures.And adding 2g fulvic acid had significant effect of plant height,but had less effect of yield and other indicators.It is also not recommended as a measure for reducing phytotoxicity.In addition,the mitigation effect of adding 5g biochar and 3g biochar is not much different.Considering the economic benefits,screening 3g biochar is an effective measure.（4）In this experiment,the physiological mechanism of effective measures screened from the four aspects of photosynthetic parameters,chlorophyll fluorescence parameters,active oxygen metabolism indexes and herbicide residues was explored.It resulted that adding naian,1g humic acid and 3g biochar could increase the Fv/Fo and Fv/Fm in leaf of adzuki beans,resulting in relatively decreasing damage to the PSII reaction center,thereby promoting photosynthesis and resulting in higher light energy conversion efficiency.And these measures also increase the chlorophy II a,chlorophy II b,total chlorophy II concentrations and photosynthetic（Pn）of leaf,which laid the foundation for the accumulation of photosynthetic products in late stage of crops growth.In addition,the accumulation of residual amounts of acetochlor and atrazine in the fruits of crop decreased,resulting the quality of crops improved.Adding 1g humic acid and 3g biochar could increase the superoxide dismutase（SOD）activity,peroxidase（POD）activity,catalase（CAT）activity,effectively removing the active oxygen free radicals in the leaves of adzuki beans and peppers.But adding naian was effective in reducing the phytotoxicity of adzuki beans and had useless for peppers.