外生菌根真菌菌丝对马尾松苗氮素传递的影响

为探究外生菌根真菌菌丝对马尾松Pinus massoniana幼苗氮素的吸收、传递及分配规律的影响，本研究应用¹⁵N示踪技术，采用四室隔网系统进行盆栽试验。研究表明：供体接种外生菌根真菌后，根外菌丝能够穿过粘土层和隔离层到达受体室，在供、受体植株之间形成菌丝桥。接种不同外生菌根真菌均显著增加供体植株苗高、地径及生物量(P<0.05)，但对受体植株的影响有差异，其中接种橙黄硬皮马勃Scleroderma citrinum (Sc)对植株苗高、地径及生物量具有显著的促进作用(P<0.05)。接种对供、受体植株全氮含量无显著性的规律(P>0.05)，只有接种东方豆马勃Pisolithus orientalis (Po)的植株全氮含量显著高于其他处理。接种能够显著提高供体植株根、茎、叶的吸氮量，且叶>根>茎，受体植株中，接种Po、Sc和褐环乳牛肝菌Suillus luteus (Sl)的植株总吸氮量较不接种(NE)显著增加(P<0.05)，而接种混合菌(Sm)的植株与NE无显著差异(P>0.05)。接种Sl的植株¹⁵N传递率最高(75.86%)，受体植株对¹⁵N吸收量最大(91.68 μg/pot)，Po次之。供体植株中，除接种Sl的植株¹⁵N主要分配在叶外，其他处理的¹⁵N分配中心均在根部，在受体植株中，接种Po、Sl、Sm的植株¹⁵N主要分配在根部，而NE和接种Sc的植株¹⁵N主要分配在茎。综上，在马尾松供、受体苗木间能形成菌丝桥，接种外生菌根真菌能够促进马尾松供体植株苗高、地径的生长及生物量的积累，提高植株吸氮量，对于受体植株不同菌种的作用有差异，其中接种Sc的苗木表现最好。此外，不同的菌种菌丝对植株的全氮含量、¹⁵N吸收量、传递率及分配率的影响也不同，其中，以接种Po和Sl的苗木表现较好。

Effects of ectomycorrhizal fungal hyphae on transfer of nitrogen among Pinus massoniana seedlings

To investigate the effect of ectomycorrhizal fungal hyphae on nitrogen absorption, transmission and distribution among masson pine seedlings, a pot experiment was carried out by using ¹⁵N tracer technique and four-compartment mesh system. The results showed that the mycelia in the donor plants inoculated with ectomycorrhizal fungi could pass through the clay layer and isolation layer and reach the recipient chamber, forming a mycelial bridge between the donor and receiver plants. The seedling height, ground diameter and biomass of donor plants were significantly increased after inoculation (P<0.05), but the effects on receiver plants varied with fungal species. Inoculation of Scleroderma citrinum (Sc) had a significant promoting effect on the seedling height, ground diameter and biomass of receiver plants (P<0.05). There was no significant difference in the total nitrogen content of donor and receiver plants after inoculation with different fungal species (P>0.05), except that the total nitrogen content of the plants inoculated with Pisolithus orientalis (Po) was significantly higher than that inoculated with other fungi. The nitrogen uptake of root, stem and leaf of donor plants was significantly increased after inoculation (P<0.05), and the level of increase was graded as root>stem>leaf. Total nitrogen uptake of the receiver plants inoculated with Po, Sc and Suillus luteus (Sl) increased significantly (P<0.05), while there was no significant difference in total nitrogen uptake between plants inoculated with the mixed ectomycorrhizal fungi (Sm) and plants uninoculated (NE) (P>0.05). The receiver plants inoculated with Sl had the highest uptake (91.68 μg/pot) and transmissivity (75.89%) of ¹⁵N, followed by those inoculated with Po. Among the donor plants, except that ¹⁵N was mainly distributed in the leaves of the plants inoculated with Sl, ¹⁵N was all distributed in roots of plants inoculated. Among the receiver plants inoculated with Po, Sl and Sm, ¹⁵N was the mainly stored in roots, while those treated with NE and Sc ¹⁵N was mainly distributed in stems. In conclusion, mycelium bridge can be formed between the donor and receiver masson pine seedlings, and inoculation of ectomycorrhizal fungi can promote the height, ground diameter, biomass accumulation and improve nitrogen absorption of donor plants, but the effects of different fungal species on receiver plants were different, and Sc was the best inoculum. In addition, different fungal species have different effects on the total nitrogen content, ¹⁵N uptake, transfer and allocation rate of the seedlings, and Po and Sl behaved better.