No abstract

Many coumarins have been identified from natural sources, especially green plants. These compounds affect many plant activities and can also control growth processes. The effect of coumarin (COU) on germination, early growth, nutrient mobilization, and some physiological parameters of faba bean (Vicia faba L.) was researched. Seeds of faba bean were primed with different concentrations of COU (0.5, 1.0, 2.0, and 4.0 mM) to elucidate the effect on germination and nutrient mobilization. Accordingly, a greenhouse pot experiment was conducted to study the effect of 1.0 mM COU, as a seed priming treatment alone or in combination with foliar application, on the growth parameters, some biochemical constituents from primary and secondary metabolism and phytohormones of faba bean. The impact of COU was more pronounced on growth than germination, and was dependent on concentration and the mode of application. Both COU treatments significantly improved the level of primary and secondary metabolites as well as phytohormones. These data suggest that COU can affect the growth and physiology of faba bean either directly, as an active growth substance, or indirectly by its interaction with the metabolism of phytohormones.

The use of actinomycetes for improving soil fertility and plant production is an attractive strategy for developing sustainable agricultural systems due to their effectiveness, eco-friendliness, and low production cost. Out of 17 species isolated from the soil rhizosphere of legume crops, 4 bioactive isolates were selected and their impact on 5 legumes: soybean, kidney bean, chickpea, lentil, and pea were evaluated. According to the morphological and molecular identification, these isolates belong to the genus Streptomyces. Here, we showed that these isolates increased soil nutrients and organic matter content and improved soil microbial populations. At the plant level, soil enrichment with actinomycetes increased photosynthetic reactions and eventually increased legume yield. Actinomycetes also increased nitrogen availability in soil and legume tissue and seeds, which induced the activity of key nitrogen metabolizing enzymes, e.g., glutamine synthetase, glutamate synthase, and nitrate reductase. In addition to increased nitrogen-containing amino acids levels, we also report high sugar, organic acids, and fatty acids as well as antioxidant phenolics, mineral, and vitamins levels in actinomycete treated legume seeds, which in turn improved their seed quality. Overall, this study shed the light on the impact of actinomycetes on enhancing the quality and productivity of legume crops by boosting the bioactive primary and secondary metabolites. Moreover, our findings emphasize the positive role of actinomycetes in improving the soil by enriching its microbial population. Therefore, our data reinforce the usage of actinomycetes as biofertilizers to provide sustainable food production and achieve biosafety.

An infographic diagram that summarizes the influence of SiNP-seed priming upon tomato plants under Orobanche infection conditions. GRW: growth, PHO: photosynthesis, NEAO: non-enzymatic antioxidants, ASE: antioxidant-scavenging enzymes.