Mixture design of microalgal consortia reveals crop-specific biostimulant formulations for bean and rice

Microalgae have emerged as promising biostimulants for sustainable agriculture; however, the rational design of microalgal consortia tailored to specific crops remains poorly explored. In this study, a mixture design approach was applied to develop optimized microalgal formulations based on Chlorella vulgaris , Scenedesmus sp ., and Arthrospira platensis , using bean ( Phaseolus vulgaris L., ecotype ‘Sangre Toro’) and rainfed rice ( Oryza sativa L., cv. ‘Fedearroz 2020’) as model crops. A simplex lattice design combined with response surface methodology and desirability analysis enabled the identification of optimal species combinations for each crop. The cubic model showed the best fit (P < 0.05), with high predictive capacity and non-significant lack of fit. Optimal formulations differed markedly between crops, revealing species-specific responses: In beans, the optimal formulation consisted of 31.6% C . vulgaris and 68.4% Scenedesmus sp., whereas in rainfed rice the best mixture included 62.3% A. platensis and 37.7% C . vulgaris . These findings demonstrate that microalgal formulations should be designed as crop-specific systems rather than universal formulations. This study provides a quantitative framework for the rational development of tailored microalgal bioinputs, contributing to more efficient and sustainable agricultural practices.