Effects of cyanobacterial-based biostimulants on plant growth and development: a case study on basil (Ocimum basilicum L.)

In the coming years biostimulants will play a key role in the sustainable intensification of agriculture due to their capacity to improve crops quality, nutrient use efficiency and tolerance to abiotic stresses. Cyanobacteria are nowadays considered one of the most promising sources of new biostimulants; however, in vivo studies using cyanobacteria are still scarce and often limited to a few genera. In this work the biostimulant activity of five cyanobacterial hydrolysates was evaluated on Ocimum basilicum L. grown in hydroponics. Plants were treated weekly with foliar applications of the cyanobacterial hydrolysates and of two commercial products. Three of the tested cyanobacterial hydrolysates, administered at the concentration of 1 g L-1, were effective in increasing plant growth (up to +32%), and number (up to +24%) and fresh weight (up to +26%) of the leaves compared to controls. Moreover, the cyanobacterial hydrolysates performed better than the commercial biostimulants. The biochemical characterization of the hydrolysates suggests that the observed bioactivity can be related to a high carbohydrate content. Our results indicate that cyanobacteria-based biostimulants can be an effective tool for sustainably enhancing plant growth and yields.