The use of potential biostimulants is of broad interest in plant science for improving yields. The application of a humic derivative called fulvic acid (FA) may improve forage crop production. FA is an uncharacterized mixture of chemicals and, although it has been reported to increase growth parameters in many species including legumes, its mode of action remains unclear. Previous studies of the action of FA have lacked appropriate controls, and few have included field trials. Here we report yield increases due to FA application in three European Medicago sativa cultivars, in studies which include the appropriate nutritional controls which hitherto have not been used. No significant growth stimulation was seen after FA treatment in grass species in this study at the treatment rate tested. Direct application to bacteria increased Rhizobium growth and, in M. sativa trials, root nodulation was stimulated. RNA transcriptional analysis of FA-treated plants revealed up-regulation of many important early nodulation signalling genes after only 3 d. Experiments in plate, glasshouse, and field environments showed yield increases, providing substantial evidence for the use of FA to benefit M. sativa forage production.

中文翻译：

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黄腐酸促进饲料豆类生长，诱导结瘤和信号相关基因的优先上调。


使用潜在的生物刺激剂来提高产量在植物科学中引起了广泛的兴趣。应用称为黄腐酸（FA）的腐殖质衍生物可以提高饲料作物的产量。 FA 是一种未知的化学混合物，尽管据报道它可以提高包括豆类在内的许多物种的生长参数，但其作用方式仍不清楚。之前对 FA 作用的研究缺乏适当的对照，而且很少包括现场试验。在这里，我们报告了由于在三个欧洲苜蓿品种中应用 FA 导致的产量增加，研究中包括迄今为止尚未使用的适当的营养控制。在本研究中，在测试的处理率下，FA 处理草种后没有观察到显着的生长刺激。直接施用于细菌可增加根瘤菌的生长，并且在苜蓿试验中，刺激了根结瘤。 FA 处理植物的 RNA 转录分析显示，仅 3 天后许多重要的早期结瘤信号基因就上调。在平板、温室和田间环境中进行的实验显示产量增加，为使用 FA 有利于苜蓿草料生产提供了充分的证据。