Biostimulant potential of microalgae on germination and early development of maize plants

Abstract

Abstract To meet the growing global demand for food, there is a continuous search for innovative and effective agricultural approaches. Algae-derived bioinputs have garnered significant interest in agriculture due to their biodegradable nature, capacity to restore soil fertility, and potential for plant growth biostimulation. This study aimed to evaluate the potential of microalgae extracts on the germination and initial growth of maize plants (Zea maysL.). The research included the analysis of the mineral composition of biomass from six microalgae strains (PPEQ-01, PPEQ-02, PPEQ-04, PPEQ-05, PPEQ-07, PPEQ-08) cultivated with CO2 supplementation. Factorial experiments were conducted using biomass extracts: zero (control), 50, 100, 150, and 200 mg.mL-1, prepared with dimethyl sulfoxide (DMSO) or water. Germination percentage and seedling dry mass were assessed after incubating seeds in a BOD incubator at 25 °C for 7 days. Furthermore, the effect of seed incubation with 100 mg.mL-1 biomass extracts from the mentioned strains, combined with DMSO or H2O extractors, was evaluated on plant height, dry mass of the shoot and root system, and root parameters analyzed using the WinRhizo system. The results revealed wide variation in the mineral composition of the microalgae, with strains PPEQ-01 and PPEQ-07 standing out as the most promising due to their higher nutrient content. Extracts from strains PPEQ-01, PPEQ-02, and PPEQ-04 promoted an increase in maize seed germination percentage at intermediate biomass doses, regardless of the extracting substance used. However, only the use of PPEQ-01 biomass, associated with either DMSO or H2O, led to an increase in maize seedling dry mass. Under greenhouse conditions, plant height, as well as dry mass of the shoot and root system, were influenced by both the biomass type and the extractor used. Root length was affected by the microalgae biomass type, independent of the extractor. Strain PPEQ-01(Poterioochromonas malhamenis) showed the highest potential under the evaluated conditions. It is concluded that the optimal biomass quantity and the type of extractor are decisive factors in identifying extracts that promote growth stimulation in maize plants.