Screening Of Quinclorac Degrading Bacteria And Its Remediation Effect On Rape Seedlings

Rape is the main source of edible oil in China.Its area and total production account for about 30% of the world's rapeseed area and total output.In the actual production process,due to the herbicide slather,then more and more accumulation and residues in the soil,and the effect on the growth of crops is increasing.Herbicide quinclorac is a steroid-type quinoline carboxylic acid herbicide,which is mainly used for the control of weeds in the paddy field,the weeds and some dicotyledons and sedges.Its structure is stable,the degradation is slow,and the residue time is long,which will produce the harmful effect on the growth and development of the latter rape.Based on this background,from the long-term use of quinclorac,2 strains D22 and D23 can degrade efficiently in the soil and perhaps by morphology observation,physiological and biochemical characteristics and 16 S rDNA sequence homology analysis on the appraisal,and studied its degradation characteristics;through hydroponic experiment acid in rapeseed seedling stage quinclorac phytotoxicity was studied,and preliminary study the repair effect of degradation bacteria,provides a certain theoretical basis for the application of degrading bacteria in the field,the main results were as follows:1 After enrichment,separation and purification in paddy soil which use chloroquine Lin acid in a long term,there are two strains quinclorac degradation bacteria D22 and D23,The strain D22 was identified as Klebsiella variicola and D23 was Pseudomonas monteilii.2 By gradient contrast test,using high performance liquid chromatography(HPLC)determination for the degradation rate,determine the best degradation condition for degradation bacteria D22 is 28?,pH 6.0,chloroquine Lin acid initial dosage of 50 mg/L,after 2 days,degradation rate can reach 94.94%;while the best degradation conditions for D23 is 20?,pH 6.0,chloroquine Lin acid addition ratio of the initial concentration of 50mg/L,after 2 days,degradation rate can reach 91.7%.3 Through germination tests,the tolerance of quinclorac on Fengyou NO.737,Huashuang NO.5,Huangyouza NO.62,Luyouza NO.1 and Wanyou NO.28 has been studied.Research shows that: Fengyou 737 has strong tolerance to quinclorac.Under the same concentration of quinclorac stress,the growth of root system and growth of hypocotyls of Fengyou NO.737 is better than other varieties.4 Through hydroponic experiments,the changes of chlorophyll content,root-neckgrowth,root fresh weight and root growth of rape under seedling stress were studied.The remediation effect of biodegradable strains on drug damage was studied.Studies have shown that low concentration of quinclorac has a promoting effect on the growth of rape seedlings,and high concentration has a harmful effect.When the concentration of quinclorac is less than 0.5 mg/L,quinclorac promotes the growth of rapeseed roots at the seedling stage.When the concentration of quinclorac is greater than 0.5 mg/L,quinclorac can affect the seedling root system at the seedling stage,quinclorac on root growth of rape at seedling stage;when the concentration of quinclorac is less than 1 mg/L,quinclorac promotes root-neck growth of rape seedlings.After the concentration is greater than 1mg/L,its produced a toxic effect;the concentration of quinclorac is less than at 1 mg/L,it had a promoting effect on the root weight,and when it was greater than 1 mg/L,it would cause phytotoxicity;the SPAD value of rapeseed at the seedling stage increased with the increase of quinclorac concentration.After accessing the degrading bacteria D23,the root weight was significantly increased.At the same time,when the concentration of quinclorac was 2 mg/L,the repair rate could reach 41.98%;after accessing the degrading bacteria D23,the strain D23 was applied to rapeseed chloroquine seedlings.The phytotoxicity had a repairing effect,at a higher concentration of 2 mg/L,the total root length repair rate could reach 311.48%.At the same time,the strain D23 had a promoting effect on the rape root system,and promoted 38.63% in terms of total root length.