不同氮素形态配比对三七根腐病的影响

为明确氮素形态及其配比对三七根腐病发生的影响,采用盆栽试验,研究了5种不同氮素形态配比(铵硝配比分别为0∶100、25∶75、50∶50、75∶25和100∶0)及尖孢镰刀菌(Fusarium oxysporum)侵染对三七Panax notoginseng (Burk.) F. H. Chen]生长、有效成分以及抗性指标的影响。结果表明,不同氮素形态配比对三七生物量和皂苷含量无明显影响,铵态氮(${NH_{4}}^{+}-N$)可促进可溶性糖的累积;病原菌侵染使三七叶绿素、可溶性糖和黄酮含量降低,随着${NH_{4}}^{+}-N$比例的增加,病情指数增加,过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性升高,同时伴随酚类和木质素的累积。综上所述,低铵硝配比(特别是25∶75)有利于三七的生长,可降低三七病情指数,减轻三七根腐病的发生。本研究从氮肥施用层面为三七根腐病的防控提供了理论依据。

Effect of Different Nitrogen Forms on the Prevention and Control of Panax notoginseng Root Rot

In order to determine the effect of nitrogen forms and its ratios on the occurrence of Panax notoginseng root rot, a pot experiment was conducted to study five nitrogen form ratios (ammonium to nitrate in the ratio of 0∶100, 25∶75, 50∶50, 75∶25 and 100∶0, respectively) and effects of Fusarium oxysporum infection on the growth, active components and resistance indices of P. notoginseng. The results showed that different nitrogen forms had no significant effect on the biomass and saponin content of P. notoginseng. Ammonium nitrogen promoted the accumulation of soluble sugar. The contents of chlorophyll, soluble sugar and flavonoid of P. notoginseng were decreased with the infection of pathogen. The disease index and the activities of peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were increased as the ratio of ammonium nitrogen increased, which was accompanied by the accumulation of phenols and lignin. In conclusion, the results showed that low ammonium nitrate ratio (especially 25:75) was beneficial to the growth of P. notoginseng, and could reduce the disease index and the occurrence of root rot. This study provides a theoretical basis for the prevention and control of P. notoginseng root rot from the level of nitrogen application.