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 uncharacterised 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 and hitherto unused. 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 Medicago sativa trials root nodulation was stimulated. RNA transcriptional analysis of FA-treated plants revealed upregulation of many important early nodulation-signalling genes after only three days. Experiments in plate, glasshouse, and field environments showed yield increases, providing substantial evidence for the use of FA to benefit Medicago sativa forage production.

Background: As agriculture has intensified, many once-common wildflowers have declined in arable landscapes, which has widespread implications for associated ecosystem services. The incorporation of sustainable practices, for example, growing living mulches (in-field, non-crop plant ground cover, maintained during the target crop growing season), can boost arable biodiversity, but few wildflower species have been utilised in this context. Aims: Our aim was to determine the suitability of arable wildflower species, once considered weeds, for use as living mulches. Methods: We first screened a number of arable wildflower species for germination when growing with a common cereal, barley (Hordeum vulgare). We then grew two (Centaurea cyanus and Scandix pecten-veneris) in pots in a glasshouse with and without barley, and grew barley alone to test the impact of the wildflowers on barley growth and biomass. Results: Neither of the wildflowers significantly negatively impacted barley biomass. Barley initially facilitated germination in S. pecten-veneris, but ultimately suppressed the aboveground biomass of both wildflowers. However, both wildflower species were able to coexist alongside barley. Conclusions: Our experiment provides evidence that wildflowers that were considered weeds in traditional agriculture have the potential to be grown alongside barley and could be incorporated as part of a living mulch.