Spirulina-Based Biostimulants for Sustainable Agriculture: Yield Improvement and Market Trends

Microalgae as next generation plant growth additives: Functions, applications, challenges and circular bioeconomy based solutions

“…Foliar spray of biostimulants is a commonly employed method for enhancing crop productivity in several crops owing to the faster response of plants to nutrients supplemented compared to other treatments ( Arahou et al., 2022 ). FS of biostimulants enhanced the water use efficiency and stomatal functioning of the plants ( Renuka et al., 2018 ).…”

“…Evaluation of the composition of microalgae cell hydrolysates revealed the presence of plant growth-promoting substances such as phytohormones (auxins and cytokinins), signaling molecules such as betaines, AAs, vitamins, polyamines, (spermine and spermidine), and polysaccharides mainly beta-glucan apart from micronutrients ( González-Pérez et al., 2022 ). Among the various microalgae species, extracts and hydrolysates derived from Spirulina platensis , Chlorella vulgaris and Scendesmus spp., are most utilized for FS application ( Arahou et al., 2022 ; González-Pérez et al., 2022 ).…”

“…The PAL enzyme showed immediate increase in its activity after FS while the root drenched samples showed delayed expression of the enzymes at 4 th day indicating influence of application method on the time of physiological response ( Puglisi et al., 2022 ). The immediate physiological response to FS as compared to root drenching applications could be attributed to the faster rate of absorption through stomata compared to root cells ( Hong et al., 2021 ; Arahou et al., 2022 ). This has been earlier validated with nano-fertilizer applications of micronutrients where foliar application of minerals modulated plant growth better and faster compared to soil application ( Alshaal and El-Ramady, 2017 ).…”

“…In addition to these, CPC modulated microbial diversity and abundance in the hydroponic growth medium promoting actinobacteria and firmicutes suggesting possible plant prebiotic properties of CPC by its ability to stabilize plant growth promoting bacteria and enhancing plant growth ( Varia et al., 2022 ). The major advantage of use of CPC as biostimulants is that the molecule is well characterized along with its downstream processes such as extraction and purification well standardized and commercialized ( Arahou et al., 2022 ). Further, CPC is water soluble in nature allowing its scalability as bio stimulants.…”

“…In addition, we describe the mechanism of biostimulant action of various microalgae metabolites along with their effects on plants under different modes of application namely seed treatments, foliar spray and soil drenching. Although few reviews and status papers on this topic are available, they seldom discuss the functionalities of various class of biostimulants present in microalgae ( Chiaiese et al., 2018 ; Arahou et al., 2022 ; González-Pérez et al., 2022 ). Another important highlight of this review is the description of mechanisms involved in the abiotic and biotic stress tolerances imparted by microalgae on crops along with case studies; which have not been reviewed critically in earlier reports such as ( Kapoore et al., 2021 ; González-Pérez et al., 2022 ).…”