Study On The Effects Of Fertilization And Exogenous Zn On Soil And Pakchoi

Nowadays soil heavy metal pollution is an important reason that widespread affects the food safety. Therefore, the governance of soil polluted with heavy metals has become an important research field at home and abroad. Fertilization is not only an agronomic measure to increase crop production and improve product quality, but also affects the form transformation and bio-availability of heavy metals in soil, thus affecting the ecological environment behavior. In this paper, a pot experiment with a complete combination design of two factors and four levels to study the effects of different fertilization treatments and different exogenous zinc concentrations on soil nutrient contents, zinc contents of soil and pakchoi, pakchoi biomass and resistant physiological index. For using fertilizer to promote or inhibit heavy metal uptake by plant provides theory basis. The results show that:1. Effects of different fertilization and exogenous zinc concentrations on organic matter, total nitrogen, available potassium contents of soil were not significant, while the effects on soil available phosphorus were significant. The soil available phosphorus content in chemical fertilizer+organic fertilizer treatment was the highest, the average content was145.6%higher than that in CK, followed by chemical fertilizer treatment, the average content was55.5%higher than that in CK, and the average available phosphorus content of soil in organic fertilizer treatment was14.0%higher than that in CK too. But the soil available phosphorus contents all showed a decreasing trend as exogenous zinc concentration increased under different fertilizer treatments.2. Effects of exogenous zinc treatment on soil total zinc content and zinc content of pakchoi both were significant, and fertilization significantly affected the zinc content of pakchoi, but the effect of fertilization on total zinc content of soil was not significant. The total Zn contents of soil and zinc contents of pakchoi all showed an increasing trend as exogenous Zn concentration increased in different fertilization treatment, the zinc contents of soil in1000mg·kg-1Cu treatment were216.4%～562.6%higher than that in0mg*kg-’ and the zinc contents of pakchoi in1000mg·kg-1Cu treatment were217.0%～1954.2%higher than that in 0mg·kg-1Cu treatment in different fertilization treatment. Organic manure and chemical fertilizer+organic fertilizer treatments significantly decreased the zinc contents of pakchoi, and the average Zn contents of pakchoi were17.9%and55.2%lower than that in CK respectively, but chemical fertilizer treatment had no effect on the zinc content of pakchoi.3. The effects of different fertilization treatments and exogenous zinc concentrations on plant height, plant fresh weight per plant of pakchoi were significant, but the effects on root length of pakchoi were not significant. The plant height and plant fresh weight of pakchoi in chemical fertilizer, organic manure, and chemical fertilizer+organic fertilizer treatments were significantly higher than those in CK, and the average plant height and plant fresh weight of pakchoi in chemical fertilizer, organic manure, and chemical fertilizer+organic fertilizer treatments were54.7%and323.2%,21.4%and147.9%,51.4%and301.6%higher than that in CK respectively. The plant height of pakchoi increased first and then decreased as exogenous zinc concentration increased under different fertilization treatments, while the plant fresh weight of pakchoi increased first and then decreased as exogenous Zn concentration increased in CK and organic fertilizer treatments, and decreased as exogenous Zn concentration increased in chemical fertilizer and chemical fertilizer+organic fertilizer treatments.4. The effects of different fertilization treatments and exogenous zinc concentrations on the N, P, K, and chlorophyll contents of pakchoi all were significant. The average N, P, K, and chlorophyll contents of pakchoi in chemical fertilizer, organic fertilizer, chemical fertilizer+organic fertilizer treatments were63.1%,10.7%,61.3%and108.9%,55.8%,9.4%,40.0%and88.8%,133.1%,35.1%,81.5%and108.2%higher than that in CK respectively. The nitrogen contents of pakchoi all decreased first then increased as exogenous Zn concentration increased in different fertilization treatments, the phosphorus contents of pakchoi were increased first and then decreased as exogenous Zn concentration increased in different fertilization treatments, and the chlorophyll contents of pakchoi were all decreased as exogenous Zn concentration increased in different fertilizer treatments, but the potassium contents of pakchoi had different changing patterns as exogenous Zn concentration increased in different fertilization treatments.5. The effects of different fertilization treatments and exogenous zinc concentrations on the SOD and POD activities and MDA and proline contents were all significant. The average SOD activity, POD activity, and proline content of pakchoi in chemical fertilizer, organic fertilizer, chemical fertilizer+organic fertilizer treatments were13.3%,70.0%and771.7%,8.9%,84.7%and633.6%,11.5%,67.3%and1112.8%higher than that in CK respectively, but the average MDA contents of pakchoi were17.1%,26.8%,22.7%lower than that in CK respectively. The MDA and proline contents of pakchoi were all increased as exogenous zinc concentration increased in different fertilizer treatments, the SOD activity of pakchoi increased in chemical fertilizer treatment and increased first and then decreases in the other fertilization treatments, the POD activity of pakchoi increased in organic fertilization treatment and increased first and then decreased in the other fertilization treatments.