Biochemical, physiological and microbiological aspects of extracts obtained from the algae macrocystis pyrifera. Effects of application on corn and soybean seeds

IPARRAGUIRRE, JULIA; MASCIARELLI, OSCAR; BONANCEA, SERGIO; LUNA, MARÍA VIRGINIA

La Falda- Córdoba

Workshop; VII Latin American PGPR Workshop. II Taller Latinoamericano Sobre Rizobacterias Promotoras del Desarrollo Vegetal; 2014

REDBIO

The use of concentrated and liquid extracts from seaweeds as fertilizers has grown in popularity because they have shown to promote plant growth and development. In addition, in their natural habitat, seaweeds act as niche for the development of marine endophytic bacteria which could be responsible for the synthesis of some substances such as vitamins, phytohormones, antiviral, antibacterial and antifungal compounds that contribute to the development of plants when applied in the soil, to seeds or foliar. On this basis, the aim of this study was to analyze the production of phytohormones, antifungal activity, capacity of bacterial support and bacterial species associated with algae extract from Macrocystis pyrifera and its effect on soybean and corn germination and seedling growth. Phytohormone content of the algae extract was evaluated in vitro by LC-MS-MS. In order to certify the presence of associated bacteria, a screening technique for isolation and morphological characterization of colony forming units was conducted. To assess the antifungal activity, Sclerotium rolfsii and Fusarium oxysporum were used with growth medium containing different doses of the algae extract. To study the effect on plant growth, 4 doses of the liquid extract were applied on corn and soybean seeds and germination parameters were determined. After that, seedling fresh weight was determined. To analyze the putative ability of the algae extract as physical and energetical support for bacteria, the survival of Azospirillum brasilense in inoculated seeds was evaluated by light microscopy and colony counting methods. The in vitro production of different phytohormones (SA, ABA, IAA, JA, GA1, GA3 and Zeatin) far exceeded expectations, compared to other bio-fertilizers and even to higher plants. Isolation of bacteria associated with the extract showed the presence of 5 types of morphologically different colonies. The assay for antifungal activity showed that the extract inhibits the growth of both species of fungi used. The process of germination in maize was favored in the first 48 hours following the start of imbibition of seeds treated with seaweed extract. In soybean, contrarily to treated seeds, control seeds germinated in the early hours of imbibition but treated seeds compensated when evaluating EG, which could indicate that soybean germination would be more sensitive to the osmotic potential generated by the algae. The results indicate that the extract Macrocystis pyrifera is a product with high technological potential, not only as natural and organic biological fertilizer to promote plant growth, but because of their physico-chemical and microbiological characteristics that could replace chemical products currently used as bacterial protection / adherents to seeds.