制种玉米连作对土壤氮组分含量及根腐病发病的影响OACSTPCD

To explore the relationship between endophyte,soil nitrogen and the incidence of root rot,field experiment was conducted and high-throughout sequencing technology were adopted to investigate five different continuous cropping years fields(5,10,15,20,25 years).The plots that seed corn were never been planted was taken as control(CK).The endophytic bacteria and the content of different form of nitrogen in soil was also determined.Compared with CK,the content of soil total nitrogen decreased significantly to 0.72 g/kg and the contend of ammonium nitrogen increased to 72.97 mg/kg in 25 years continuous cropping plots.The content of nitrate nitrogen and hydrolyzed nitrogen increased first and then decreased.The content of acidolytic nitrogen,hydrolyzed nitrogen and ammonium nitrogen increased significantly,while ammonia nitrogen decreased significantly in the five different continuous cropping plots.With exception of continuous cropping of five years,the content of amino acid nitrogen increased significantly,while the content of total nitrogen,non-acidolytic nitrogen and amino sugar nitrogen decreased significantly(P＜0.05).At the genus level,there were 13 dominant bacteria genera in the root of maize,among which Pseudomonas,Rhizobium,Sphingomonas,Pedobacter and Pantoea had the highest abundance.There were ten dominant fungi genera,among which Peniophora,Aspergillus,Schizophyllum and Phialemoniopsis had the highest abundance.The continuous cropping had no significant effect on the types of bacteria and fungi rhizobacteria,but the relative abundance was changed in different continuous cropping years.The incidence of root rot of seed corn increased significantly.The incidence of root rot was positively correlated with the contents of soil acidolytic nitrogen,amino acid nitrogen,hydrolyzed nitrogen,ammonium nitrogen and nitrate nitrogen(P＜0.01),but negatively correlated with content of soil total nitrogen and non-acidolytic nitrogen(P＜0.01).The incidence of root rot was positively correlated with the relative abundance of Fusarium and Aspergillus(P＜0.05).In conclusion,the contents of soil available nitrogen,especially acidolytic nitrogen and non-acidolytic nitrogen were significantly correlated with the relative abundance of dominant pathogens and the incidence of root rot in corn seed production(P＜0.05),which could be used to accurately predict the occurrence of root rot in maize production.