非硝酸盐还原细菌K18降低TSNA机理的初步研究

Mechanism of Non-nitrate Reduction Endophytic Bacteria K18 on TSNA Reduction

对21株烟草内生细菌还原硝酸盐和亚硝酸盐的能力进行检测,验证了非硝酸盐还原细菌K18的内生性,并鉴定为嗜麦芽寡养单胞菌(Stenotrophomonas sp.)。结果表明,用K18菌株对烟草进行移栽前浸根、团棵期喷施、旺长期喷施及采前喷施处理,可有效降低烟叶中TSNA含量,降低程度与烟草品种有关。温室中TSNA的降低作用与烟叶的细菌数量相关,K18处理的云烟87,团棵期和旺长期烟叶细菌数量增高,TSNA分别降低23.7%和9.1%;云烟87和TN86经K18处理后,NNN降低百分率最高,而且对TN86各组分的降低百分率高于云烟87。对于大田栽培的云烟87,旺长期喷雾和浸根处理可显著降低烟叶中TSNA含量,与清水对照比较,分别使TSNA含量降低了50.1%和39.6%。对于大田栽培的TN86,旺长期喷雾、调制期喷雾和浸根处理使烟叶中TSNA含量分别降低52.6%,51.1%和44.7%。

From all tobacco endophytic bacteria, 21 strains were tested for their ability to reduce NO3^- to NO2^-, the endophytic characteristic of strain K18 which didn＇t have the ability on nitrate reduction was confirmed and was tested for the ability on TSNA reduction in greenhouse and in field. Tobacco were treated with K18 on different growing stage, such as root dipping during transplanting, spraying on tobacco leaves during branching and luxuriant growing stage, spraying a week before harvest, and chemical contents of TSNA in the leaves were examined. Results showed that the amount of TSNA in the leaves was different responding to different treatment of bacteria K18 on different tobacco variety. The total amount of TSNA was reduced at all treatments with K18 in greenhouse and in field, but the reduction efficacy was related to the tobacco variety. TSNA reduction was suspected to relate to the total bacterial number in tobacco leaves, The total bacterial number in tobacco leaves treated with K18 during the branching stage and luxuriant growing stage was higher than that control, and the TSNA reduction rate reached 23.7% and 9.1% respectively. NNN, a major content of TSNA was reduced effectively at the treatments by K18 either in YunYan87 or in TN86. And it was higher in TN86 than that in YunYan87 In terms of YunYan87 planted in field, the reduction rate could reach 50.1% and 39.6% respectively at the treatment of spraying luxuriant growing stage and root dipping stage compared to the treatment without K18.And as to TN86 grew in field, the reduction rate reached 52.6%, 51.1% and 44.7% respectively at the treatment of spraying luxuriant growing stage, the treatment of spraying at curing and the treatment of root dipping compared to control.