Potencial de Nostoc sp. e Trichoderma harzianum na tolerância da soja à salinidade

Abstract

Seed inoculation with bioinputs such as cyanobacteria Nostoc sp. and fungus Trichoderma harzianum may be a promising and sustainable alternative for activating defense pathways and inducing salinity tolerance in soybean. We aimed to evaluate the potential of Nostoc sp. and T. harzianum to mitigate the effects of salinity on soybean seedlings. Soybean seeds cv. CZ 37B51 IPRO were subjected to the following inoculations: (i) Nostoc sp., (ii) T. harzianum, (iii) Nostoc sp. + T. harzianum, in addition to the control (iv), all exposed or not to NaCl-induced salinity. Without NaCl, inoculation of the bioinputs alone or in combination favored the activation of the antioxidant enzymes peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and proline. NaCl did not impair root protrusion or seed germination, but it reduced seedling vigor. Soybean was sensitive to salinity, decreased seedling growth and biomass accumulation, but inoculation with Nostoc sp. and T. harzianum maintained vigor by being more efficient in activating enzymatic and osmoregulatory mechanisms. Defense pathways were activated differently and varied with the inoculation of each bioinput. In NaCl, proline, total protein, and CAT increased with T. harzianum, while with Nostoc sp. + T. harzianum, POD increased. The highest SOD activity occurred in seedlings without bioinputs in NaCl. In NaCl, seedlings with Nostoc sp. and T. harzianum alone or in combination showed greater biomass accumulation. The combination of bioinputs showed a synergistic effect, positively impacting seedling performance. Finally, Nostoc sp. and T. harzianum act as effective anti-stress agents, with the potential to induce salt stress tolerance through biochemical adjustments and maintain the vigor of soybean seedlings.