Effect Of Zinc Treatments On Eukaryotic Microorganisms In Soil And Productivity Of Crops

Zinc（Zn）deficiency in soils is one of the reasons that cause a reduction in the productivity of maize and green bean plants.Maize（Zea mays L.）is a multipurpose cereal crop for food,fodder,and industrial resources such as alcohol,ethanol fuel,starch,glue,and oil.The green bean（Phaseolus vulgaris L.）is one of the world’s most important grain legumes for human food.Soil application of Zn is an effective strategy for increasing yield and Zn concentration in plants.However,the effect of the soil application of Zn on the nutrient uptake and yield of maize and green beans still needs more studies,as Zn is a heavy metal that may accumulate in the soil.Therefore,its environmental impact in agroecosystems requires more analysis.In China,a field experiment was conducted during the 2019 and 2020 growing seasons to evaluate the effects of the optimum Zn doses(0,5.7,and 11.4 kg ha^-1)on maize grain yield and soil eukaryotic alpha and beta diversity.A plot experiment after the outburst quarantine of COVID-19 was conducted in Egypt on the green beans because maize is not possible realistic in the calcareous soil in Egypt.However,the experiment was designed to evaluate the effect of Zn doses and sources（zinc sulphate and zinc chloride）on the productivity and Zn biofortification in the green bean.The research on the maize indicates that applications of Zn had no influence on soil respiration rate or eukaryotic microorganisms’diversity in the same year.Nonetheless,Zn dosages had a weak variable effect on the community structure of eukaryotic microorganisms.The number of detected OTUs of soil eukaryotic microorganisms decreased in 2020 compared with 2019,with significant variation in the beta diversity in 2020 compared to 2019 in a newly cultivated field.The arbuscular mycorrhizal（AM）fungi of the genus Rhizophagus were positively affected by Zn 5.7 kg ha^-1 in 2020.As the eukaryotic microorganisms did not feed on the Zn salt,their change over the two years indicated the evolution of ecosystem（maize/purple soil）be more important than the input of Zn fertilization.In maize plants,soil application of Zn was found to significantly increase chlorophyll soil plant analysis development（SPAD）values,Zn,and P concentration in the maize shoot at the VT stage as well as the grain Zn,P,and Mg concentration in grains with a Zn application of 11.4 kg ha^-1.Furthermore,the 1000 grain weight,kernels per spike,and overall grain yield.In the green bean plant,Zn applications significantly increased chlorophyll SPAD values,Zn in all plant tissues,and DTPA Zn in the soil.Applying ZnSO₄ at 11.4 kg ha^-1 had a greater effect on chlorophyll in the leaf and N,P,and S in grain when compared to the same dose of zinc chloride.The phytic acid（PA）concentration in maize grains was also increased with a Zn application of 11.4 kg ha^-1.The PA/Zn molar ratio in grains decreased due to the Zn application doses as compared with the control treatment,but there was no significant difference between Zn 5.7 and 11.4 kg ha^-1.In green beans,Zn doses significantly decreased the PA/Zn molar ratio compared to the control treatment.The soil type（purple soil in China and calcareous soil in Egypt）with different p Hs and water content could affect the P availability in the soil and hence the P concentration in the plant,which has an effect on the production of PA and the PA/Zn molar ratio.Zn application is beneficial for raising Zn concentration in maize grains and crop yield as a result of benefiting the physiology.In our study,zinc fertilizer alone is neutral to the diverse community of soil eukaryotic microorganisms,but the maize/soil system along with the growth year is the key to the change of eukaryotic living beings.Furthermore,Zn has a positive and significant effect on the Zn concentration,Zn bioavailability,and yield of green beans,with a better effect of zinc sulphate source compared to zinc chloride.