Arthrospira maxima hydrolysate as a high value biofertilizer in basil (Ocimum basilicum L.) seedlings

Abstract Continued increase of human populations and use of chemical fertilizers remain a threat to the health and stability of human-ecological systems worldwide. To ameliorate this problem and achieve sustainable agriculture, a variety of ecofriendly technologies have been developed, including the production of cyanobacteria-based biofertilizers. This technology can be optimized through experiments that assess how plant growth is enhanced under different biofertilizer concentrations (g L− 1). Here we assess the biofertilizer potential of hydrolysates derived from the cyanobacteria Arthospira maxima on the growth of basil (Ocimum basilicum) under six different concentrations (0, 2.5, 5, 10, 20, and 40 g L− 1), and an additional treatment where we applied the registered product Optimar ® (4 mL L− 1). For all response variables except stem length, a concentration of 40 g L− 1 yielded significantly higher values. The beneficial effects of the application of Optimar were often surpassed when plants received cyanobacteria concentrations above 10 g L− 1. A chemical composition analysis of A. maxima revealed high concentrations of the phytohormones gibberellic acid (0.19 g L− 1), 6-benzyladenine (0.37 g L− 1), and 1-naphthaleneacetic acid (0.25 g L− 1) that are likely responsible for the cyanobacteria’s biostimulant activity. Further research is required to determine how other crop plants respond to different concentrations of A. maxima and the viability of creating an economically accessible product with a higher concentration of A. maxima using circular economy and biorefinery concepts to obtain high value-added by-products.