Nitrogen Fixation and Resorption Efficiency Differences Among Twelve Upland and Lowland Switchgrass Cultivars
Nitrogen Fixation and Resorption Efficiency Differences Among Twelve Upland and Lowland Switchgrass Cultivars
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DOI：
10.1094/pbiomes-11-19-0064-fi
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发表时间：
2020-08
影响因子：
4.4
通讯作者：
Sarah S. Roley;Tayler C. Ulbrich;G. Robertson
中科院分区：
文献类型：
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作者：
Sarah S. Roley;Tayler C. Ulbrich;G. Robertson
在氮(N)有限的陆地生态系统中，植物采用各种策略来获取和保存N，包括多年生组织中N的转运和刺激根系和土壤中的N固定。柳枝稷（Panicum virgatum）是一种基因型和表型多样化的多年生草本植物，具有两种不同的生态型（低地和高地）和众多的基因型。它在低氮土壤中生长良好，可能是因为它具有转运氮的能力，并与固定氮的微生物相关联，但对这些性状在栽培品种甚至生态型之间的变化知之甚少。在美国密歇根州西南部进行了12个柳枝稷品种的重复块体试验，测定了其氮素转运、根系和土壤的固氮势、土壤净氮矿化、土壤净硝化和生物量产量。低地品种具有更高的产量、氮转运速率、土壤净氮矿化和在洗净、非不育根系上的氮固定电位，而高地品种在无根土壤中表现出更高的氮固定电位。低地品种氮吸收效率平均为53±5%（±标准误差），而高地品种为29±3%。此外，除矿化和硝化作用外，所有响应变量在品种间均存在显著差异，这可能与品种特有的生理和微生物群落有关。生物燃料的理想品种是那种可以用最少的肥料保持高产量的品种，而且似乎有几种品种符合这些标准。此外，研究结果表明，品种间氮素循环的巨大差异可能被育种者利用，以创造新的或改良的高产、保氮柳枝稷品系。
In nitrogen (N)-limited terrestrial ecosystems, plants employ various strategies to acquire and conserve N, including translocation of N in perennial tissues and stimulation of N fixation in roots and soils. Switchgrass (Panicum virgatum) is a genotypically and phenotypically diverse perennial grass with two distinct ecotypes (lowland and upland) and numerous genotypes. It grows well in low-N soils, likely because of its ability to translocate N and to associate with N-fixing microbes, but little is known about variation in these traits among cultivars or even ecotypes. We measured N translocation, N fixation potential in roots and soils, soil net N mineralization, soil net nitrification, and biomass yields in 12 switchgrass cultivars grown in a replicated block experiment in southwestern Michigan, United States. Lowland cultivars had higher yields, rates of N translocation, soil net N mineralization, and N fixation potentials on washed, nonsterile roots, while upland cultivars exhibited higher N fixation potentials in root-free soil. N resorption efficiencies averaged 53 ± 5% (± standard error) for lowland versus 29 ± 3% for upland cultivars. Additionally, there were significant among-cultivar differences for all response variables except mineralization and nitrification, with differences likely explained by cultivar-specific physiologies and microbial communities. The ideal cultivar for biofuels is one that can maintain high yields with minimal fertilizer addition, and there appear to be several cultivars that meet these criteria. In addition, results suggest substantial N cycle differences among cultivars that might be exploited by breeders to create new or improved high-yielding, N-conserving switchgrass lines.