Plant lignin content and composition, which limit cell wall digestibility and efficiency of cellulose conversion to bioethanol, can be influenced by belowground biotic and abiotic factors. Switchgrass (Panicum virgatum L.) is a leading lignocellulosic biofuel crop and forms strong belowground associations with arbuscular mycorrhizal fungi (AMF), is susceptible to belowground plant-parasitic nematodes (PPN), and when grown in monoculture generally requires nitrogen (N) fertilization. The main objectives of the study were to investigate the effects of N fertilizer and belowground organisms on lignin content and composition of switchgrass. Leaf, stem, and root tissues were evaluated separately to test whether these factors had varying belowground (local) or aboveground (systemic) effects on plants. These factors were manipulated in a field study in 2017 using biocide applications to reduce soil fungi and nematodes. Combined biocide application reduced p-hydroxyphenyl (H) unit abundance in the leaves by 14% and increased the syringyl:guaiacyl (S:G) ratio in stems by 2%. Application of fungicide alone increased stem syringyl (S) unit by 12.4% as compared with control plots, and 11.1% as compared with nematicide plots. Overall, fertilizer increased total stem lignin by 3%, stem S unit by 6.7%, and stem S:G ratio by 10%, whereas it reduced the amount of H-unit in the roots by 11%. While the effects of N fertilizer were more pronounced in this study, changes to soil organisms had similar magnitudes of effect for some measures of lignin, indicating that these belowground interactions may be important for growers to consider in the future.

植物木质素的含量和组成会限制细胞壁的消化率和纤维素转化为生物乙醇的效率，这可能会受到地下生物和非生物因素的影响。柳枝（（Panicum virgatumL.）是一种领先的木质纤维素生物燃料作物，与丛枝菌根真菌（AMF）形成强烈的地下关联，易受地下植物寄生线虫（PPN）的侵害，并且在单一种植中生长时通常需要氮（N）施肥。该研究的主要目的是研究氮肥和地下生物对柳枝of木质素含量和组成的影响。分别评估叶，茎和根组织，以测试这些因素对植物的地下（局部）或地下（系统）作用是否有所不同。这些因素是在2017年的一项田间研究中使用杀生物剂减少土壤真菌和线虫而得到控制的。联合使用杀生物剂可将叶片中的对羟基苯基（H）单元丰度降低14％，并增加丁香基：愈创木脂（S：G）茎中的比率降低了2％。与对照样地相比，单独施用杀真菌剂可使茎丁香基（S）单位增加12.4％，与杀线虫剂地相比增加11.1％。总体而言，肥料使总茎木质素增加了3％，​​茎S单位增加了6.7％，茎S：G比增加了10％，而根中H单位的含量减少了11％。尽管在本研究中氮肥的作用更为明显，但对于某些木质素措施，土壤生物的变化具有相似的影响幅度，这表明这些地下相互作用可能对种植者今后的考虑很重要。而根部的H单位减少了11％。尽管在本研究中氮肥的作用更为明显，但对于某些木质素措施，土壤生物的变化具有相似的影响幅度，这表明这些地下相互作用可能对种植者今后的考虑很重要。而根部的H单位减少了11％。尽管在本研究中氮肥的作用更为明显，但对于某些木质素措施，土壤生物的变化具有相似的影响幅度，这表明这些地下相互作用可能对种植者今后的考虑很重要。