Seed treatment of soybean, wheat, and oat with cyanobacteria extracts: Germination and field performance analysis

Abstract

Microalgae biostimulants have gained attention as a promising solution for sustainable approaches in agriculture. This study assessed Spirulina platensis biostimulants in seed treatment (ST) for soybean, wheat, and oat. In the first stage, laboratory tests evaluated early plant growth and compared two biomass disruption methods: ultrasonic probe (1%, 5%, 10% m/v); and freeze/thaw (5% m/v). In the second stage, field experiments with soybean applied optimal ST concentrations, testing combinations of chemical, biological, and microalgal treatments, with and without conventional fertilization. The cyanobacteria extract produced by ultrasonic probe disruption, rich in amino acids and nutrients, enhanced the emergence speed index of wheat plants by up to 6.8% in laboratory tests compared to the control. In the early stages of plant development, the cyanobacteria extract positively affected the root growth of soybeans, wheat, and oat, increasing the dry root biomass of soybeans by up to 26.9%. In the second stage, treatments with cyanobacteria resulted in greater plant height (up to 12%) and dry mass (up to 32%) in the shoot compared to treatments with only chemical seed treatment. Under field conditions, microalgal treatments increased shoot length and dry mass compared to chemical seed treatments. They also enhanced nodule formation by up to 50%, whereas conventional fertilizer reduced nodule development. The results showed that these extracts may enhance the physiological characteristics of plants, and their biostimulant properties suggest benefits for various cultivars, with no negative effects when combined with chemical and biological treatments for soybean ST.