| Arsenic entered the soil and was transformed by the transformation of the food chain,posing a threat to human health.Therefore,in this experiment,"Jingu 21?JG21?,Qihuang 2?QH2?,Dabai?DB?"?Setaria italica?was selected as the test material,which the method of pot experiment was used to explore the seedling stage and jointing of arsenic.By exploring the effects of arsenic on the growth and physiological characteristics of millet seedling,jointing and maturity stage,the absorption and transport of As by plants,the critical concentration range of arsenic on the physiological stress of millet was determined,and then the arsenic tolerance mechanism of millet was preliminarily investigated.The results showed that:?1?At different growth stages,with the increase of As concentration,the biomass of DB,JG21 and QH2 increased first and then decreased.when As concentration ?10 mg·kg-1,the biomass increased and promoted the growth of millet.As concentration >10 mg·kg-1,the biomass decreased gradually,and its critical concentration was 10 mg·kg-1.?2?In different growth stages,with the increase of As concentration,the effects of chlorophyll and photosynthetic parameters of DB,JG21 and QH2 increased first and then decreased.Low concentration of As(?10 mg·kg-1)can improved the synthesis of chlorophyll,increased the sensitivity of stomatal conductance?Gs?opening and closing,enhanced the accumulation of CO2,increased the photosynthetic rate,and enhance the photosynthesis of millet.As the concentration of As increased(>10 mg·kg-1),it destroyed the photosynthesis of millet,and the correlation between As concentration and maturity chlorophyll in maturity period showed that the correlation between chlorophyll a and As concentration was better.?3?With the increase of As concentration,the activities of SOD,CAT and POD of DB,JG21 and QH2 increased first and then decreased,and the enzyme activities in different periods were: seedling stage > jointing stage > mature stage;malondialdehyde and soluble protein content In different growth stages: maturity > jointing stage,the content of proline is: jointing stage > maturity stage.When the concentration of As was less than or equal to 10 mg·kg-1,the physiological indexes such as SOD,POD and CAT activities of millet were decreased.?4?At the maturity stage,the enrichment factor of millet roots was significantly higher than that of stems and grains,mainly accumulated in the roots.The enrichment ability of As in different parts was: roots> stems and leaves> grain,and the accumulation of As and the exogenous sources in different parts As concentration increases consistently.With the increase of As treatment concentration,the transport coefficient of millet gradually decreased,mainly accumulated in the roots,and the As content of grain was far lower than the national green food limit standard(seed As ? 0.7 mg·kg-1).?5?Correlation analysis between the As concentration at maturity and the physiological indexes of millet showed that when As concentration was ?10 mg·kg-1,it mainly increased the synthesis of chlorophyll,increased the content of prolin and increased the activity of POD at the same time,so that the millet grows normally;As concentration >10 mg·kg-1,the content of MDA,proline and chlorophyll b in millet is decreased,which will inhibit the growth of millet. |
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