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    氮添加及接种处理对1年生樟子松苗木根系形态及养分含量的影响

    Responses of root morphology and nutrient content of Pinus sylvestris var. mongolica seedlings to nitrogen addition and inoculation treatments

      摘要
    • 摘要:
        目的  探究1年生樟子松苗木根系构型和养分吸收对氮添加及接种外生菌根真菌的响应机制。
        方法  以1年生樟子松菌根苗（8种外生菌根真菌混合接种，HJ）和非菌根苗（未接种，WJ）为研究材料，设置4个氮添加处理试验，分别为：不施氮（CK，0 kg/（hm2·a））、低氮（LN，15 kg/（hm2·a））、中氮（MN，30 kg/（hm2·a））和高氮（HN，60 kg/（hm2·a）），对比分析氮添加和接种处理对苗木根系形态（总根长、总表面积、总体积、分叉数、根尖数、平均直径等）和养分含量的影响。
        结果  （1）在CK、MN、HN处理下，接种处理间苗木生物量存在显著差异；CK处理下，菌根苗生物量较非菌根苗提高了54.3%；而MN和HN处理下，菌根苗生物量较非菌根苗分别下降17.8%、23.7%。（2）氮添加和接种处理显著影响1年生樟子松苗木直径0 ~ 0.5 mm根系的总根长、总表面积、根尖数；在WJ处理下，随着氮添加量递增，樟子松苗木根系形态指标均呈先上升后下降的趋势；而在HJ处理下，随着氮添加量递增，其根系形态指标均呈下降的趋势。（3）与CK相比，氮添加显著增加非菌根苗氮、磷养分含量；而对菌根苗氮、磷养分含量的影响表现为LN处理促进，HN处理抑制。
        结论  低氮添加和接种处理对苗木根系形态和养分含量表现为协同效应，而高氮添加处理削弱接种处理对苗木根系形态和养分含量的影响。

       

      Abstract:
        Objective  The aim of this study was to investigate the responses of root architecture and nutrient absorption capacity of one-year-old Pinus sylvestris var. mongolica to nitrogen addition and inoculation of ectomycorrhizal fungi.
        Method  The one-year-old mycorrhizal (mixed inoculated with 8 ectomycorrhizal fungi, HJ) and non-mycorrhizal (no inoculation, WJ) seedlings of P. sylvestris var. mongolica were selected. Four nitrogen addition treatments were set, including no nitrogen (CK, 0 kg/(ha·year)), low nitrogen (LN, 15 kg/(ha·year)), middle nitrogen (MN, 30 kg/(ha·year)) and high nitrogen (HN, 60 kg/(ha·year)) treatments. The root morphology (including the total root length, surface area, volume, bifurcations, tips, average diameter) and nutrient content of the seedlings were measured.
        Result  (1) There were significant differences between the seedling biomass of two inoculation treatments under CK, MN and HN treatments. Under CK treatment, the biomass of mycorrhizal seedlings increased by 54.3% than that of the non-mycorrhizal seedlings. Under MN and HN treatments, the biomass of mycorrhizal seedlings decreased by 17.8% and 23.7% than that of non-mycorrhizal seedlings, respectively. (2) The total root length, surface area, number of tips of one-year-old P. sylvestris var. mongolica seedlings with diameter of 0 − 0.5 mm were affected significantly by the nitrogen addition and inoculation treatments. Increasing of nitrogen addition, the root morphological indexes of non-mycorrhizal seedlings showed a tendency of first increased and then decreased, but that of mycorrhizal seedlings showed a decreasing tendency. (3) Compared with CK, the nitrogen and phosphorus contents of the non-mycorrhizal seedlings were significantly increased by nitrogen addition treatments, but that of mycorrhizal seedlings was promoted by LN treatment and inhibited by HN treatment.
        Conclusion  There is a synergistic effect of low nitrogen addition and inoculation treatments on the root morphology and nutrient content of seedlings. The effect of inoculation on root morphology and nutrient content of seedlings is weakened by high nitrogen addition.

       

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