Effects Of Mixed Alkaline Salts On Root Enzymes And Rhizospheric Microorganisms Of Sugar Beet Seedlings

Sugar beet?Beta vulgaris L.?is the main sugar crop and energy crop,with strong salt tolerance.The effect of mixed alkaline salt on the changes of root and Rhizosphere micro ecology under was studied.Our results will provide theoretical reference for the further study on the rhizospheric effect of sugar beet.The pot experiment was conducted with KWS0143 and Beta464 as test materials.alkaline salt Na HCO₃ and Na₂CO₃ molar ratio of 2:1 mixture was applied to the soil with four levels of salt concentration,0,5,7 and 9 g/kg,marked with A0,A2,A3 and A4,respectively.The corresponding EC value of the four treatments was 127.67,559.33,782.67,and 981.67,respectivy,and the corresponding p H value was 7.20,9.18,9.40,and 9.56,respectively.some root indice were determined including fresh root weight,dry root weight,root activity,root morphology,superoxide dismutase?SOD?,peroxidase?POD?,catalase?CAT?activity,malondialdehyde?MDA?content,endogenous hormone content,root extracs type and content,rhizosphere microbial community and quantity,and soil enzyme activity.The results are as follows:1.The germination rate of sugar beet seedlings decreased with the increase of alkaline concentration.The root dry weight,fresh weight and root morphology index?length,surface area,volume?decreased on June 2nd,while root activity increased;the root dry weight,fresh weight,root activity and root morphological index?length,surface area,volume?first increase,and decreased on June 16 and 30.The value of those indice at A3 was significantly higher than control?P<0.05?,and at A4 was significantly lower compared to control and the value of those indice for KWS0143 was higher than Beta464.over the sampling time,the dry root weight,fresh root weight,root activity and root morphological index?length,surface area,volume?of the root of the beet seedlings showed an increasing trend.There was significantly positive correlation among dry root weight,root activity and root length,root surface area,and root volume.2.With the increase of alkcline concentration,MDA content increased,while the activity of protective enzymes?SOD,POD,CAT?first increased,and then decreased.The content of IAA,BR and ABA increased with the increase of alkaline concentration,while ZR decreased.the ratio of IAA/ABA decreased,BR/ABA increased and ZR/ABA decreased with the increase of treatment concentration on June 2nd.The contents of endogenous hormones?IAA,ZR,BR,ABA?and the ratio of the 3 true leaves were all the same as those of the protective enzymes on June 30 th.All of them were first increased and then decreased,the activity at A3 was highest,and the activity with A4 was lowest,which was significantly different from A0.Over the sampling time,the MDA ontent and activity of root protective enzymes?SOD,POD,CAT?increased.Endogenous hormone BR increased,while IAA,ZR,and ABAl first increased,and then decreased.the corresponding ratio of BR/ABA increased,IAA/ABA and ZR/ABA decreased.Correlation analysis showed that there was positive correlation between the activity protective enzymes?SOD,POD,CAT?.correlation beween hormone content and content of IAA,ZR,BR was significantly or extremely significantly positive.3.83 of types sugar beet root extracts were detected,including alkanes,alkenes,esters,alcohols,ketones,phenols,aldehydes,acids,pyridine,thiazole,amines,naphthalene and so on.The most common types are of esters and alkanes.there are 46 more kinds of root extracts on 2nd day than on 30 th day,including alkanes?fourteen alkanes,fifteen alkanes,seventeen alkyl phenols?2,4-?,tert butyl phenol,2,6-Di tert butyl p-cresol etc.?and esters?PAEs two formic acid butyl ester 1-methyl nonyl ester,phthalic acid butyl ester two 2-ethylhexyl phthalate,two formic acid and two isopropyl?.At the two sampling periods,the root extracts were hihgest at A3,lowest at A4 and the types of root extracts for KWS0143 were higher than Beta464.4.Activity of soil urease,alkaline phosphatase,catalase and microorganism amount was highest at A3,there was significant difference among four treatments.Over sampling time,urease activity decreased,catalase activity rose,and alkaline phosphatase activity first rose and then decreased.The number of microorganisms in rhizosphere soil was as follows: bacteria > actinomycetes > fungi.On 30 th day?3 pairs of leaves?,the number of bacteria was A3>A2>A0>A4,fungi was A3>A2>A0>A4 and Actinomyces was A0>A3>A2>A4,significant difference.The urease,alkaline phosphatase,catalase activity and the number of bacteria and actinomycetes in rhizosphere of KWS0143 were higher than that of Beta464,and the number of fungi was K<B.Correlation analysis showed that there was significantly positive correlation between urease activity and the number of bacteria and the total amount of microorganisms.Catalase activity was positively correlated with the number of Actinomycetes.