The present study aimed to chemically profile the hydroalcoholic extracts from the microalgae (MEs) Nannochloropsis oculata, Phaeodactylum tricornutum, Tetradesmus obliquus, and Tetraselmis tetrathele and evaluate their effects on the development of Colletotrichum lindemuthianum and anthracnose symptoms, as well as on the initial growth of bean plants. For this, MEs were analyzed using UPLC coupled with a mass spectrometer, allowing the identification of peaks and annotation of potential metabolites. Fungal mycelial growth was assessed seven days after inoculation, and conidial germination was measured 72 h after incubation, using ME concentrations of 0, 0.1, 0.5, and 1.0 mg·mL⁻¹. Bean seeds of the IPR Uirapuru cultivar were sown and treated with 3 mL of extracts at four time points: at sowing and 72 h after each previous treatment. After 11 days of cultivation in a growth chamber, the plants were divided into two groups: one for anthracnose control assessment and the other for evaluating growth promotion by MEs. Plant length as well as fresh and dry weights of shoots and roots were determined, leaf pigments were quantified, and anthracnose severity was assessed using a diagrammatic scale. The UPLC analysis identified 32 compounds in the extracts of the four microalgae, belonging to different chemical and functional groups, with lipids being the most significant fraction. The extracts exhibited variability and diversity in chemical composition depending on the microalgal species. MEs did not affect mycelial growth yet increased the germination of C. lindemuthianum conidia, regardless of the dose or species used. Anthracnose severity was not affected by the microalgae extracts. Regarding growth promotion, the extracts showed varying effects but generally increased shoot and root length, fresh biomass, and leaf pigment content.

The biological invasions are considered the second biggest threat to global biodiversity (Wilson 1975; Williamson & Griffiths 1996; McNeely et al. 2001; Bellard et al. 2016). It is characterized as...

Wheat (Triticum aestivum) is an important crop produced worldwide. Natural or synthetic products including phytostimulants, biofertilisers, biostimulants, bioregulators or phytoprotectors have been developed over the years. The objective of this study was to evaluate the effects of foliar application of micronutrients (essential minerals), growth regulators, extracts of the microalga Porphyridium cruentum and their mixtures on variables related to the growth and production of wheat (height of the plants at harvest, number of tillers per plant, weight of 1000 grains, pod length and yield). The experiment consisted of randomised blocks with four replications, consisting of 16 treatments (control, Zn, B, Cu, Mn, Zn+Cu+B+Mn, indolebutyric acid (AIB), 6-benzylaminopurine (BAP), Zn+Cu+B+Mn+AIB+BAP, P. cruentum freeze-dried polysaccharide (PS), P. cruentum freeze-dried material (FM), Zn+Cu+B+Mn+PS+FM, AIB+BAP+FM+gibberellic acid (GA), commercial-B, commercial-A and commercial-E). The single foliar application of micronutrients, commercial products containing micronutrients, growth regulators (indolbutyric acid, 6-bezylaminopurine, gibberellic acid and their mixtures), freeze-dried polysaccharide and biomass of P. cruentum, and mixtures of micronutrients and growth regulators did not potentiate the development and productivity of the wheat crop. The average height of wheat plants at harvest was 77.81 cm and ranged from 80.05 cm when the comercial-E product was applied to 74.43 cm with the application of P. cruentum polysaccharide extract at a dose of 62 g ha-1, which resulted in lower crop yield, although the difference was not significant. Additionally, the individual application of the P. cruentum polysaccharide extract did not significantly influence on plant growth.

Raphidiopsis raciborskii (formerly Cylindrospermopsis raciborskii) is a bloom-forming cyanobacterium that employs the production of toxins and other secondary metabolites as a competitive and allelopathic strategy. This study evaluated the effects of exudates from R. raciborskii cultivated under three nitrogen-to-phosphorus (N:P) ratios on the photosynthetic performance of Limnothrix sp. (cyanobacterium), Chlorella sp. (green algae), and Raphidocelis subcapitata (green algae), using pulse-amplitude-modulated (PAM) fluorometry. Rapid light curves (rETR) obtained under different N:P ratios and across the three target species exhibited similar response patterns. Likewise, effective quantum yield (ΦPSII), regulated (Y(NPQ)) and non-regulated (Y(NO)) energy dissipation showed comparable profiles among treatments after 24 h of exposure. Overall, the results of the present study indicate that, within the 24 h exposure period and based on the fluorescence parameters measured, exudates produced by R. raciborskii under the tested nutrient conditions did not cause measurable alterations in the photosynthetic performance of the three evaluated species.