Effects Of Exogenous Improver And Lead In Irrigation Water On Rice Growth And Lead Accumulation

Irrigation of farmland with sewage has become a way to alleviate the shortage of agricultural irrigation water in recent years.However,due to the sewage treatment is not up to standard,the residual heavy metal lead in agricultural irrigation water is absorbed by rice roots and enter rice.After being eaten by humans,it will cause various degrees of harm to human health.Therefore,this article starts with how to reduce the absorption of lead in rice in irrigation water and ensure the safety of rice.Zeolite and biochar were selected as soil amendments and a two-factor randomized block design was used for the study.Using rice as a test material.Based on the control of farmland irrigation water quality(Pb?0.2 mg·L^-1),the irrigation water with lead concentration of 0,0.15,0.25 mg·L^-11 was used to irrigate rice at different growth stages.The dosage of zeolite is 0 t·hm^-2?Z₀?,2.5 t·hm^-2?Z₁?and 5 t·hm^-2?Z₂?.The dosage of biochar is 0 t·hm^-2?C₀?,5 t·hm^-2?C₁?and 10 t·hm^-2?C₂?and two sets of tests were carrried out.To study under the different lead concentrations in irrigation water,effects of two modifiers on soil properties,rice growth,yield,and lead content in different growing organs in rice fields.Through the construction of a regression model to explore the relationship between the amount of modifier used,the concentration of lead in irrigation water,and lead content and yield in rice.Get the following main conclusions:?1?Different lead concentrations in irrigation water and the amount of modifiers have different effects on soil properties.High lead concentrations in irrigation water significantly reduce soil fertility.Different amounts of zeolite can significantly increase soil pH,available phosphorus and available potassium content.In the lead-free conditions of irrigation water,zeolite has no significant effect on soil pH and available potassium content.However,when the lead concentration in the irrigation water is low,the addition of different amounts of zeolite has a significant effect.Compared with Z₀,the contents of pH and available potassium increased by 3.71%⁴.52%and 18.93%²6.03%.Zeolite has no significant effect on available phosphorus in lead-free or low lead levels in irrigation water.However,when the lead concentration in irrigation water is high,the addition of low-use zeolite significantly inhibits the available phosphorus content,which is 9.12%lower than that of Z₀.Different biochar dosages have significantly improved various soil properties.The application of biochar can significantly increase the content of soil properties.With the increase of lead concentration in irrigation water,the addition of high-dose biochar has better effect on soil pH increase.Under the lead-free and high-concentration lead levels in irrigation water,biochar has no significant effect on improving soil available phosphorus content.When the lead concentration in irrigation water is low,the addition of high-dose biochar can significantly increase the soil available phosphorus content,which is 15.92%higher than that of C₀.?2?The different lead concentrations in irrigation water and the amount of modifier have different effects on rice growth and yield.When the lead concentration in the irrigation water is low,it can slightly promote rice growth..But when the concentration is high,it plays a significant inhibitory effect.Lead in irrigation water has an inhibitory effect on rice yield,and the higher the concentration,the more significant the inhibitory effect.Zeolite and biochar can both increase biomass at various parts of rice and yield.The effect of zeolite is best when the dosage is 10 t·hm^-2,and the effect is best when the amount of biochar is 5 t·hm^-2.When the lead concentration in irrigation water is low,the addition of high amount of zeolite can significantly increase total rice biomass,which is 17.39%higher than that of Z₀.Under the lead-free condition of irrigation water,the best effect of increasing the yield of rice was 10t·hm^-2,which was 1.05 times that of C₀ treatment.Under the low or high level of lead concentration in the irrigation water,the rice production was best when the biomass was 5t·hm^-2,which was 1.03 and 1.05 times that of the C₀ treatment.?3?The different lead concentrations in irrigation water and the amount of modifier have different effects on lead content in various organs of rice.Lead in irrigation water can increase lead content in various organs of rice.Both the application of zeolite and biochar can reduce the lead content in various organs of rice,but this effect is different when the lead concentration in irrigation water is different.Adding zeolite can reduce the lead content in rice roots under the condition of lead-free irrigation water.In lead-containing conditions in irrigation water,the amount of lead in the applied zeolite is slightly increased,but the effect is not significant.In the lead-free level,different amounts of zeolite have no obvious effect on reducing lead content in rice stems,leaves and rice.With the increase of lead concentration in irrigation water,the addition of high-quantity zeolite(5t·hm^-2)can significantly reduce lead content in various organs,among which lead content in rice has the largest decrease,which is reduced by 61.99%and 68.64,respectively,compared with Z₀.Biochar has no significant effect on the reduction of lead in rice roots,leaves and rice under lead-free conditions in irrigation water.With the increase of lead concentration,the inhibitory effect is significant.Compared with C₀,the lead content of each organ was reduced by 11.85%¹9.49%,28.10%³3.22%,and 60.00%⁶0.86%,respectively,which was the best for improving the quality rice.?4?By regression analysis,it can be seen that for rice planted under lead in irrigation water,the rice yield can be indirectly improved by adding zeolite or biochar to reduce the lead content in rice.In summary,by adding zeolites and biochar,the adverse effects of lead in farmland irrigation water on paddy soil,rice growth,and rice food safety can be reduced.And provide reference for reducing the toxic effects of lead-contaminated water on crops and ensuring food security.