Nitrogen fertilization alters the functioning of arbuscular mycorrhizas at two semiarid grasslands
Nitrogen fertilization alters the functioning of arbuscular mycorrhizas at two semiarid grasslands
复制标题
DOI：
10.1023/a:1015792204633
复制
发表时间：
2002-03-01
期刊：
影响因子：
4.9
通讯作者：
Allen, EB
中科院分区：
文献类型：
--
作者：
Corkidi, L;Rowland, DL;Allen, EB
在两个具有不同土壤性质和富氮历史的半干旱草原（科罗拉多的短草草原和新墨西哥州的塞维利亚国家野生动物保护区）研究了施氮（N）对丛枝菌根的影响。这些地点是国家科学基金会长期生态研究网络的一部分。1971年至1975年，在短草草原的试验田施肥与硝酸铵（NH 4 NO3），并没有收到额外的N从那时起。Sevilleta的实验地块也用NH 4 NO3施肥，但建立于1995年，即土壤用于本研究的2年前。温室试验进行了比较当地的草丛枝菌根（AM）真菌从施肥（FERT）和未施肥（CELERT）领域的土壤中，在每个站点的生长反应。每个样地选择两个物种，来自短草草原的Bouteloua gracilis和Elymoides，和B。股薄肌和B.来自塞维利亚的eriopoda植物在高氮和低氮水平下生长3个月，用FERT或BERGERT土壤接种物和在非菌根条件下生长。施肥与N改变了AM真菌在这两个网站的功能。接种AM真菌的牧草分蘖最多，生物量最大，相对生长速率最高。有没有显着差异的生长反应接种AM真菌从肥土壤和非菌根控制的植物。这些结果是一致的网站和物种，除了在低N在Sevilleta土壤中生长的植物。这些植物缺乏氮和磷（P），并没有表现出增长的增强响应AM接种与FERT或CERTERT土壤。被AM真菌定殖的根长百分比与植物性能没有直接关系。然而，丰富的N始终降低AM真菌在短草草原土壤中生长的草的根定殖具有较高的P可用性（18.4毫克公斤（-）1），但不是在Sevilleta土壤中生长的草低P可用性（6.6毫克公斤（-）1）。我们的研究支持了以下假设：（1）施氮改变了菌根共生的成本和效益之间的平衡，（2）施氮土壤中的AM真菌群落比未施氮土壤中的AM真菌群落的互利性更低。
The effects of nitrogen (N) fertilization on arbuscular mycorrhizas were studied at two semiarid grasslands with different soil properties and N-enrichment history (Shortgrass Steppe in Colorado, and Sevilleta National Wildlife Refuge in New Mexico). These sites are part of the National Science Foundation's Long-Term Ecological Research Network. The experimental plots at Shortgrass Steppe were fertilized with ammonium nitrate (NH4NO3) from 1971 to 1975, and have not received additional N since then. The experimental plots at Sevilleta were also fertilized with NH4NO3, but were established in 1995, 2 years before the soils were used for this study. Greenhouse experiments were conducted to compare the growth response of local grasses to arbuscular mycorrhizal (AM) fungi from fertilized (FERT) and unfertilized (UNFERT) field soils, at each site. Two species per site were chosen, Bouteloua gracilis and Elymus elymoides from Shortgrass Steppe, and B. gracilis and B. eriopoda from Sevilleta. Plants were grown for 3 months at HIGH N and LOW N levels, with FERT or UNFERT soil inoculum and in a non-mycorrhizal condition. Fertilization with N altered the functioning of AM fungi at both sites. Grasses inoculated with AM fungi from UNFERT soils had the most tillers, greatest biomass and highest relative growth rates. There were no significant differences in the growth response of plants inoculated with AM fungi from FERT soils and the non-mycorrhizal controls. These results were consistent across sites and species except for the plants grown at LOW N in Sevilleta soils. These plants were deficient in N and phosphorus (P) and did not show growth enhancement in response to AM inoculation with either FERT or UNFERT soils. Percent root length colonized by AM fungi was not directly related to plant performance. However, enrichment with N consistently decreased root colonization by AM fungi in the grasses grown in soils from Shortgrass Steppe with high P availability (18.4 mg kg(-)1), but not in the grasses grown in Sevilleta soils with low P availability (6.6 mg kg(-)1). Our study supports the hypotheses that (1) fertilization with N alters the balance between costs and benefits in mycorrhizal symbioses and (2) AM fungal communities from N fertilized soils are less beneficial mutualists than those from unfertilized soils.