Arbuscular mycorrhizal fungi and Urochloa brizantha: symbiosis and spore multiplication

ABSTRACT Arbuscular mycorrhizal fungi (AMF) may exhibit distinct behaviors when associated with the same species of host plant, being necessary to understand their ecology, in order to optimize their management and maintenance in germplasm bank. This study aimed to evaluate different AMF associated with Urochloa brizantha (A. Rich.) Stapf by analyzing the symbiosis establishment time, spore multiplication and production of glomalin-related soil protein. The experiment was carried out in a completely randomized design, in a 6 x 5 arrangement (five AMF species, non-inoculated control treatment and five evaluation times). The following aspects were analyzed: plant growth, spore multiplication, mycorrhizal colonization and glomalin production. The highest number of spores occurred for Acaulospora longula and A. colombiana, exhibiting the highest mycorrhizal colonization at 76 days. The inoculation favored the root growth of U. brizantha at 15 days of cultivation, plant height and root dry matter at 60 days and shoot dry matter at 90 days, especially for the Acaulospora species. The inoculation with A. colombiana, A. longula and Paraglomus occultum resulted in increased glomalin at 120 days. Gigaspora margarita and P. occultum did not reach the maximum colonization and spore multiplication, indicating that a period of time longer than 120 days of cultivation is necessary.

摘要：丛枝菌根真菌（Arbuscular Mycorrhizal Fungi，AMF）与同一宿主植物物种共生时可能表现出差异化的行为特征，因此为优化其在种质资源库中的管理与保藏，明确其生态学特性具有重要意义。本研究以臂形草（Urochloa brizantha (A. Rich.) Stapf）为宿主，通过分析共生建立时间、孢子繁殖情况与球囊霉素相关土壤蛋白的产生量，对不同丛枝菌根真菌的接种效果开展评价。试验采用完全随机设计，设置6×5的处理组合（包含5种丛枝菌根真菌、1个未接种对照处理，共设置5个取样评价时间点），测定指标涵盖植株生长状况、孢子繁殖量、菌根侵染率及球囊霉素相关土壤蛋白产量。结果显示，长孢无梗囊霉（Acaulospora longula）与哥伦比亚无梗囊霉（Acaulospora colombiana）的孢子数量最多，且在培养76天时达到最高菌根侵染率。接种处理可促进臂形草生长：接种后15天即可观察到根系生长优势，培养60天时对株高与根干物质积累具有显著促进效果，培养90天时则显著提升地上部干物质积累，该效应在无梗囊霉属（Acaulospora）真菌的接种处理中尤为突出。接种哥伦比亚无梗囊霉、长孢无梗囊霉与隐类球囊霉（Paraglomus occultum）的处理组，在培养120天时的球囊霉素相关土壤蛋白产量显著升高。巨孢球囊霉（Gigaspora margarita）与隐类球囊霉的处理组未达到最大菌根侵染率与孢子繁殖量，表明该试验体系下需设置超过120天的培养周期才能完成相关指标的完整测定。