• ISSN 1008-505X
  • CN 11-3996/S

接种兰科菌根真菌对不同硝铵比条件下大花蕙兰生长、养分吸收及氮代谢的影响

Effect of orchid mycorrhizae fungus inoculation on the growth, nutrient absorption, and nitrogen metabolism of Cymbidium hybridum under different nitrate-to-ammonium ratios

    摘要
  • 摘要:
    目的 探究兰科菌根真菌(orchid mycorrhizal fungi，OMF)对不同形态氮素配比(NO3−/NH4+)条件下大蕙兰花生长及氮代谢的影响。
    方法 以大花蕙兰580和OMF兰科丝核菌C2y1为研究对象，进行盆栽试验。设置土壤浇灌和不浇灌C2y1，每个处理下分别设3个NO3−/NH4+供应比例，即8∶1 (T1)、1∶1 (T2) 和1∶8 (T3)。测定了处理后大花蕙兰幼苗生长、生物量和根系长度的增加情况，分析了处理后叶片中硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性，采用PCR法检测C2y1定植情况。
    结果 未接种C2y1条件下，T2处理的大花蕙兰植株鲜重增长量及干物质积累量显著高于T1和T3处理，T3处理的根系增长量显著高于T1和T2处理。PCR分析结果证明，土壤浇灌C2y1菌剂后，C2y1可有效侵入大花蕙兰根系，形成共生关系，且随着铵态氮占比的增加，根系C2y1侵染率显著增加。相比于未接种对照，接种C2y1可显著促进各硝铵比处理大花蕙兰茎叶生长和生物量积累，茎叶的最大提升效果出现在T3处理，而最大根系促生效果出现在T1处理；接种C2y1显著提高了茎叶对大量元素(N、P、K)和微量元素(Fe、Zn、Cu)的吸收，茎叶最高N、P、K和Zn含量出现在T3处理，对根系中各元素含量提升效果较小。接种和未接种C2y1条件下，大花蕙兰幼苗的NR活性都随着硝态氮比例的下降而降低，而GS活性正相反，且接种C2y1后各硝铵比处理幼苗的GS活性均显著高于未接种处理。
    结论 大花蕙兰比较喜好硝态氮，但是铵态氮可促进其根系与C2y1形成共生体来适应高铵环境。接种兰科丝核菌C2y1促进了大花蕙兰生长及对营养的吸收和运转，且在高铵环境下的促生效应大于高硝态氮环境下。

     

    Abstract:
    Objectives This study is to explore the impact of orchid mycorrhizal fungi (OMF) inoculation on the growth and nitrogen metabolism of Cymbidium hybridum under various NO3−/ NH4+ ratios.
    Methods Cultivar Cymbidium hybridum ‘580’ and OMF C2y1 were used as test materials in a pot experiment. The C2y1 inoculation was carried out by watering into soils during the seedling stage of Cymbidium hybridum, taking water as control group. Under each group, N was supplied in three different NO3−/NH4+ ratios of 8∶1 (T1), 1∶1 (T2), and 1∶8 (T3). The increased growth and biomass weight of the shoot, and the enhanced length of roots of C. hybridum seedlings were measured, the nutrient contents in both shoot and root, and the activities of nitrate reductase (NR) and glutamine synthetase (GS) in leaves were analyzed. PCR method was used to confirm the infection of C2y1 fungi.
    Results Without inoculation, the significantly higher fresh weight growth and dry matter accumulation of C. hybridum were recorded under T2, while the significantly higher root growth was recorded at T3. The PCR results proved the infection of C2y1 on the root of C. hybridum through the soil watering method, and the infection intensity was enhanced with the increase of ammonia nitrogen supply ratio. Compared to the no inoculation control, C2y1 inoculation significantly enhanced shoot growth and biomass accumulation of C. hybridum under various nitrogen form ratios, with the largest promotion on shoot growth under T3 treatment, and the highest promotion on root was under T1 treatment. C2y1 inoculation significantly enhanced the absorption of N, P, K, Fe, Zn, Cu. Notably, with the highest concentrations of N, P, K, and Zn in shoot under T1 ratio, while their concentration in roots were not affected by C2y1 inoculation. The NR activity in C. hybridum seedlings under C2y1 inoculation was positively correlated with the nitrate nitrogen supply ratios, while GS activity was on the contrary.
    Conclusions C. hybridum prefers nitrate to ammonia, however, ammonia is conducive the infection of C2y1, which help C. hybridum to adapt to the soil environment. Inoculation of C2y1 could stimulate the growth and nutrient absorption, and the promotion effect under high ammonia environment is even more obvious.

     

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