Study On The Yield-Enhancing Effect Of Iron Chlorine E6 On Allium SativumL And Its Degradation Behaviors In Environment

Iron chlorine e6 is a new type of plant growth regulator（PGRs）.It was patented in2011 by Nanjing Baxter Biologicals Co.,Ltd.in China,and officially registered and marketed as a pesticide in China in 2018,its mechanism of action is to inhibit chlorophyll degrading enzyme activity in plants.Iron chlorine e6 could improve crop yield and resilience such as oilseed rape,wheat and rice,but its application effect and environmental degradation behavior on garlic are not clear.In this paper,we investigated the experimental effect of iron chlorine e6 on the growth regulation of garlic,it residue analysis method of iron chlorine e6 in garlic and soil and its degradation behavior in garlic,soil and water,to provide a reference for the security of use and environmental risk assessment of this agent.The content of this test is as follows:（1）To investigate the effect of iron chlorine e6 on garlic yield,a field efficacy trial was conducted from September 2021 to May 2022 during the growth period of garlic.Iron chlorine e6 was applied once during the overwintering period and once during the greening period of garlic,which could promote the above-ground plant height,leaf surface and length of garlic moss to increase the yield of garlic moss significantly,The active ingredient of 0.04-0.16 mg/kg treatment increased the yield of garlic moss by 6.31%-6.98%,which was significantly higher than that of 0.02 mg/kg treatment,whlie the difference with the control treatment of 0.04 mg/kg homobrassinolide were not significant,respectively;The 0.02%iron chlorine e6 SP was applied once during the overwintering period,once during the greening period and once after the harvesting of garlic moss.Compared with the clear water treatment,the treatment of 0.04 mg/kg showed a significant increase in the cross-sectional diameter and the proportion of quality bulbs,a significant increase in the fresh weight of individual bulbs,and an increase of 8.61%in the unit yield of garlic,while all other treatments showed a decrease in the fresh weight and yield of individual bulbs.Therefore,the recommended dose of 0.02%iron chlorine e6 SP is 1250-5000 times dilution（amount of active ingredient 0.04-0.16 mg/kg）when harvesting the above-ground part of garlic and 5000 times dilution（amount of active ingredient 0.04mg/kg）when harvesting the below-ground part of garlic,respectively.（2）A high-performance liquid chromatographic（HPLC）method was established for the determination of iron chlorine e6 in garlic plants and soil.Iron chlorine e6 was determined by high performance liquid chromatography（HPLC）on a Zorbax Eclipse XDB-C18（5μm,250 mm×4.6 mm）column with an injection volume of 10μL,a column temperature of 25℃,a mobile phase of acetonitrile:0.1%phosphoric acid=55:45（V/V）and a detection wavelength of 399 nm.The recoveries of iron chlorine e6 in the range of0.02～5 mg/L were determined to be 98.60%～101.31%with standard deviations less than0.55%for the instrumental analysis method when iron dihydroporphyrin chloride was used as the calibration peak.Considering that iron chlorine e6 is highly polar and insoluble in pure water and acetonitrile,iron chlorine e6 spiked in garlic plants and soil was extracted using salting-out assisted liquid-liquid extraction（SALLE）,which was based on methanol/dipotassium hydrogen phosphate biphasic extraction with PSA and C18purification of the supernatant.The recoveries of the method for 0.05,0.1 and 0.5 mg/kg spiked samples ranged from 86.36%to 96.65%with mean standard deviations of 1.84%to8.47%.Therefore,the method meets the requirements for the determination of iron chlorine e6 residues in garlic plants and soil matrices.（3）To clarify the degradation dynamics of iron chlorine e6 in soil,the degradation behaviour of iron chlorine e6 in three types of soil was investigated by indoor simulation tests.At an initial residue level of 1.0 mg/kg,the degradation rate of iron chlorine e6 in different soils was in the order of Jilin black soil>Jiangxi red soil>Hainan red soil;while the rate of degradation of iron chlorine e6 in the same soil under different conditions was in the order of waterlogging anaerobic>aerobic>sterilization>organic matter removal;The degradation rates of iron chlorine e6 in the different soil treatments were well fitted using the first order kinetic equation.The degradation half-lives ranged from 1.19 to 3.99d,with chemical factors significantly more influential than microbial factors.The degradation of iron chlorine e6 was also investigated in natural conditions,with half-lives ranging from 1.69 to 3.16 d in three types of soil in summer and winter.（4）To investigate the hydrolysis and photolysis characteristics of iron chlorine e6under different conditions.The results showed that the hydrolysis and photolysis of iron chlorine e6 at constant temperature are in accordance with the primary kinetic law.The hydrolysis half-lives of iron chlorine e6 was 0.11～31.50 d,which were at the easy degradation level.The effects of p H,temperature,and metal ions(Cu²⁺)on the hydrolysis rate were significant,while the effects of microorganisms,initial concentration and NO₃^-concentration were not.Iron chlorine e6 is structurally stable in an acidic environment,with high activation energy（Ea）and activation entropy（△S）,both of which are not significantly correlated with temperature.The photolysis type of iron chlorine e6 was direct,with half-lives was 1.27～3.62 h under deuterium light source,which belonged to the easy photolysis level.The effects of Cu²⁺on the photolysis rate of iron chlorine e6 was significant,while the effects of NO₃^-,HA,and FA concentrations on the photolysis rate were not.Therefore,iron chlorine e6 is a readily degradable pesticide in water.