施氮量对烟株接种黑胫病前、后体内生理物质及黑胫病发生的影响

Effect of nitrogen application rate on physiology of flue-cured tobacco plants with or without inoculation of Phytophthora parasitica var. nicotianae and the severity of black shank

以红花大金元烤烟品种为材料,采用盆栽接种法研究了供氮水平(分别为N 71、142、213和284 mg/kg)对烟株感染黑胫病前、后体内多酚氧化酶(PPO)、过氧化氢酶(CAT)活性和总酚、类黄酮、可溶性糖、游离氨基酸、总氮等生理物质含量及黑胫病发病情况的影响。结果表明:1)烟株接种后5和15 d时体内PPO和CAT的活性以及总酚、类黄酮、可溶性糖、游离氨基酸、总氮等生理物质含量均有高于同期未接种烟株的趋势,且不同供氮水平下趋势一致。2)接种当天及接种后5和15 d,接种和未接种烟株体内总氮和游离氨基酸的含量均以高氮处理大于低氮处理,而CAT活性和总酚、类黄酮、可溶性糖含量则相反;高氮和低氮处理间差异显著;而PPO活性则以施N 142和213 mg/kg处理显著高于施N 71和284 mg/kg处理。3)高施氮量下,烟株接种黑胫病后的发病率和病情指数呈现出较高的现象。上述表明,氮营养不仅影响着烟株初期(即接种病原前)的抗性,而且影响着诱发抗性(即接种病原后诱发的抗性)的强弱;这在一定程度上导致了不同施氮量烟株黑胫病病害发生的差异。说明调控施氮量有助于增强烟株抗性,减少黑胫病的发生。

The effect of different nitrogen（N） application rates（N 71,142,213 and 284 mg/kg） on polyphenol oxidase（PPO） and catalase（CAT） activity and the contents of phenols,flavonoids,soluble sugars,free amino acids,and total nitrogen,as well as the incidence and severity of black shank in flue-cured tobacco（Nicotiana tabacum L.cv.Hongda） plants,was studied in a pot culture experiment with or without inoculation of the black shank pathogen（Phytophthora parasitica var.nicotianae）.The results showed that inoculation of black shank pathogen led to higher PPO and CAT activities,and higher contents of phenols,flavonoids,soluble sugars,free amino acids,and total nitrogen in the tobacco plants 5 and 15 days after inoculation（DAI） compared to non-inoculated plants.A similar tendency was found under the different N application rates.Increasing N amount caused higher contents of N and free amino acids,but decreased contents of flavonoids,phenols and soluble sugars and lowered CAT activity,in both inoculated and non-inoculated tobacco plants 0,5 and 15 DAI.The highest and lowest nitrogen amounts induced significant differences in the above-mentioned biochemical indices.Activity of PPO was higher in the N 142 and 213 mg/kg treatments than in the N 71 and 284 mg/kg treatments.In addition,increased severity of black shank was observed with increasing N application rate.Overall,the results indicated that N application rate affected not only the initial resistance（pre-infection of the pathogen）,but also the induced resistance（post-infection）,which in turn resulted in the different occurrences of black shank.Optimal N management is recommended to decrease the severity of black shank in the commercial production of N.tabacum cv.Hongda.