Queiroz Luana M D, Dubeux Jose C B, Sollenberger Lynn E, Vendramini Joao M B, Liao Hui-Ling, Jaramillo David M, Santos Erick R S, Abreu Daciele S, Lira Mario A, Casagrande Daniel R, Mackowiak Cheryl L, Ruiz-Moreno Martin
Agronomy Department, Institute of Food and Agricultural Sciences, North Florida Research and Education Center, University of Florida, Marianna, FL, USA.
Agronomy Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA.
Sci Rep. 2025 Jul 8;15(1):24514. doi: 10.1038/s41598-025-08988-y.
Legumes are a potentially important N source in pasture systems, but quantifying the transfer of biologically fixed N from the legume to the grass component is difficult. A greenhouse H-pot system was developed to directly estimate belowground N transfer from biological N fixation (BNF) using N. The system was tested with 'Prine' annual ryegrass (Lolium multiflorum L.) and 'Dixie' crimson clover (Trifolium incarnatum L.). Legume and grass root systems growing in either individual or H pots were exposed to N. Control H pots were separated by mesh to prevent contact between roots from each side of the pot. To reduce enriched gas volume demand and avoid cross-contamination in the greenhouse, the gas was supplied through underground tubes in the root zone. Ryegrass and clover exhibited an enrichment of N when their respective root systems were supplied with N. Additionally, ryegrass also showed enrichment when clover roots received the gas, provided there was direct contact between the root systems on both sides of the H pot; however, this enrichment did not occur when such contact was prevented. Plants cultivated in monoculture without the application of N did not present enrichment. The H-pot facilitates the evaluation of belowground transmission, an essential mechanism for N transfer. The technique of gradually supplying N directly to the root system may serve as a valuable labeling method for tracking nitrogen transfer. The absence of enrichment when plants were not directly supplied indicates negligible atmospheric enrichment. However, the enrichment observed in ryegrass when supplied with the gas suggests BNF through alternative pathways.
豆科植物在牧场系统中可能是一种重要的氮源，但量化从豆科植物到禾本科植物部分的生物固氮转移量却很困难。开发了一种温室H型盆系统，以直接利用氮来估计生物固氮（BNF）的地下氮转移。该系统用‘Prine’一年生黑麦草（多花黑麦草）和‘Dixie’绛车轴草（绛三叶）进行了测试。在单个盆或H型盆中生长的豆科植物和禾本科植物根系暴露于氮。对照H型盆用网隔开，以防止盆两侧的根系接触。为了减少富集气体的需求量并避免温室中的交叉污染，气体通过根区的地下管道供应。当黑麦草和三叶草各自的根系供应氮时，它们表现出氮的富集。此外，当三叶草根系接受气体时，如果H型盆两侧的根系有直接接触，黑麦草也会表现出富集；然而，当这种接触被阻止时，这种富集就不会发生。在不施氮的单一栽培中种植的植物没有表现出富集。H型盆便于评估地下传输，这是氮转移的一个重要机制。直接向根系逐渐供应氮的技术可能是一种有价值的标记方法，用于追踪氮的转移。当植物没有直接供应时没有富集现象，这表明大气富集可以忽略不计。然而，当供应气体时黑麦草中观察到的富集表明通过替代途径进行生物固氮。
