The Effects Of Copper Stress On Flax Germination,Yield And Physiological Characteristics

Copper has become one of the main polluting elements in the soil contaminated by heavy metals in southern China.The problem of soil copper pollution needs to be solved urgently.Fiber flax?Linum usitatissimum L.?does not enter the food chain.Flax can be grown in winter in the southern region.Flax has strong tolerance to heavy metals and can be used as a candidate crop for remediation of heavy metal contaminated soil.Cu SO₄�5H₂O?analytical pure?was used to simulate copper stress environment in this experiment.Five copper concentrations of 0,50,100,150 and 200 mg/L were setted to study the effect of copper stress on the germination characteristics of 9 flax varieties.The effects of copper stress on Agronomic and physiological characteristics of flax were studied by mixing copper contaminated soil and common soil in different proportions?0:1,1:4,1:2,1:1 and 1:0,recorded as T₁,T₂,T₃,T₄and T₅?.The results showed that:?1?Copper inhibited the germination of flax and significantly reduces the germination rate of flax.Low concentration copper can promote the bud growth of some flax varieties,but it is not conducive to the growth of seedlings.Nine flax varieties were classified by membership function method.Parks and Longya No.10 were high-tolerance types,Yiya No.5,Yunya No.3,Tongshengfu,Tianxin No.1 and Yiya No.3 were medium-tolerance types.Yiya No.4 is a low resistance type,and Yunya No.1 is sensitive type.?2?Low-concentration copper can significantly promote flax growth and increase flax yield.T₃ treatment had the most obvious promoting effect on flax growth.When the copper concentration in the soil is 1564.58 mg/kg?T₃?,the fresh weight per plant,stem weight per plant and raw flax weight per plant increased by 58.34%,55.27%and 43.92%respectively compared with T₁;high-concentration copper can significantly inhibit flax growth and reduce flax yield.When the copper concentration in the soil reached 2915.32 mg/kg?T₅?,fresh weight per plant,stem weight per plant,raw flax weight per plant decreased by 68.10%,69.39%and 52.44%respectively compared with T₁.?3?The chlorophyll content of flax leaves decreases with the increase of copper concentration.As the accumulation of copper ions in flax increases,the overall performance is that the malondialdehyde?MDA?content and peroxidase?POD?activity increase first and then decrease with the increase of copper concentration.Catalase?CAT?activity and total superoxide dismutase?SOD?activity increased with the increase of copper concentration in the early period of copper stress,decrease first and then increase with the increase of copper concentration in the later period of copper stress The soluble sugar content increases as the copper concentration increases.?4?Before and after planting flax,the total copper content of the soil changed significantly.The maximum change was T₄,and the copper content in the soil was reduced by 715.44 mg/kg,which is 69.12 times of that in T₁ treatment,and 32.69%less than that before planting.Followed by T₃ treatment,the reduction is 516.03 mg/kg,which is 49.86times of that in T₁ treatment,and 32.98%less than before planting.