氮素形态对烟草黑胫病发生的影响

Effects of Nitrogen Forms on the Occurrence of Tobacco Black Shank

为寻找控制烟草黑胫病发生的有效措施,研究了硝态氮、铵态氮及其配比液对烟草黑胫病菌孢子萌发、菌丝生长以及烟株次生代谢物和抗病性的影响。结果表明,硝态氮、铵态氮及其混合液均可以加速烟草黑胫病游动孢子的萌发,二者混合溶液更有利于黑胫病菌丝的生长。随着溶液中铵态氮浓度的升高,烟株根系木质素、纤维素和MDA含量以及SOD、POD、PAL活性显著升高,增强了烟株的抗病性,从而使其发病率和病情指数显著下降。相关性分析表明,烟株黑胫病发病率和病情指数与其根系木质素、MDA含量和SOD、POD、PAL活性均极显著负相关,黑胫病发病率与纤维素含量显著负相关。因此,烟株黑胫病发病率和病情指数与其次生代谢物密切相关,铵态氮可以显著降低烟草黑胫病发病率和病情指数,但硝态氮和铵态氮最适配比及田间抗病效果还需进行大量相关田间试验研究。

In order to find effective measures to control tobacco black shank,effects of nitrate,ammonium and their different ratios on spore germination and mycelial growth of tobacco black shank as well as the secondary metabolism and disease resistance of tobacco were studied.The results showed that the germination of zoospores of tobacco black shank was accelerated by nitrate,ammonium and their mixed solutions,and the mycelia of tobacco black shank grew better in their mixed solutions.With the increasing of ammonium concentration in solutions,the contents of lignin,cellulose and MDA and the activities of SOD,POD and PAL in tobacco roots increased significantly,while the incidence and the disease index of tobacco black shank decreased significantly.The correlation analysis showed that there was a extremely significantly negative correlation between the incidence/disease index of tobacco black shank and the contents of lignin and MDA and the activities of SOD,POD and PAL(p<0.01),and there was a remarkable negative correlation between the incidence of tobacco black shank and the content of cellulose.So the results revealed that the incidence and the disease index of tobacco black shank are closely related to the secondary metabolites,which can be significantly reduced by ammonium application.However,a large number of field trials need to be carried out to study the optimal ratio of nitrate and ammonium nitrogen under field conditions.