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

Abstract

Sustainable agriculture practices involve the application of environment-friendly plant growth promoters and additives that do not negatively impact the health of the ecosystem. Stringent regulatory frameworks restricting the use of synthetic agrochemicals and the increase in demand for organically grown crops have paved the way for the development of novel bio-based plant growth promoters. In this context, microalgae biomass and derived agrochemicals offer novel sources of plant growth promotors that enhance crop productivity and impart disease resistance. These beneficial effects could be attributed to the presence of wide range of biomolecules such as soluble amino acid (AA), micronutrients, polysaccharides, phytohormones and other signaling molecules in microalgae biomass. In addition, their phototrophic nature, high photosynthetic efficiency, and wide environmental adaptability make them an attractive source of biostimulants, biofertilizers and biopesticides. The present review aims to describe the various plant growth promoting metabolites produced by microalgae and their effects on plant growth and productivity. Further, the effects elicited by microalgae biostimulants with respect to different modes of applications such as seed treatments, foliar spray and soil/root drenching is reviewed in detail. In addition, the ability of microalgae metabolites to impart tolerance against various abiotic and biotic stressors along with the mechanism of action is discussed in this paper. Although the use of microalgae based biofertilizers and biostimulants is gaining popularity, the high nutrient and water requirements and energy intensive downstream processes makes microalgae based technology commercially unsustainable. Addressing this challenge, we propose a circular economy model of microalgae mediated bioremediation coupled with biorefinery approaches of generating high value metabolites along with biofertilizer applications. We discuss and review new trends in enhancing the sustainability of microalgae biomass production by co-cultivation of algae with hydroponics and utilization of agriculture effluents.

Reduction of Oxygen Production by Algal Cells in the Presence of O-Chlorobenzylidene Malononitrile

“…( Figure 3 ). This would be useful for detoxification mechanisms in case of chemical stress through the synergistic enzymatic action of enzymes involved in cell synthesis [ 33 , 34 , 35 , 39 , 42 , 43 ].…”

“…(Figure 3). This would be useful for detoxification mechanisms in case of chemical stress through the synergistic enzymatic action of enzymes involved in cell synthesis [33][34][35]39,42,43]. The microscopic examination during the tests indicated good cellular develop with the appearance of solitary cells in the first stage, and then cell agglomeratio peared due to the flocculation of the cells, this being favorable to the protection During the tests, BP had a value of 11.31% after 15 days from the beginning of the tests and a value of 67% at the end of the test, after 30 days of cell growth, while the flocculation activity was approximately 80% [44,45].…”

Use of micro and macroalgae extracts for the control of vector mosquitoes

“…Microalgae are unicellular photosynthetic microscopic algae, typically found in freshwater and saline environments. Microalgae have been searched for their potential use in various fields including biofuels, bioremediation, and as a source of valuable compounds such as pigments, proteins, and omega-3 fatty acids ( Nagi et al, 2021 ; Parmar et al, 2023 ; Xu, Miao & Wu, 2006 ). When extracting compounds from algae, the choice of solvent and extraction method is crucial to ensuring efficient and effective extraction.…”

Chlamydomonas reinhardtii—A Reference Microorganism for Eukaryotic Molybdenum Metabolism

“…Microalgae display a wide variety of cell sizes, morphologies, and architectures, and possess a diverse metabolic capacity that provides several distinctive features for scientific investigation [ 8 ]. The biotechnological use of microalgae has experienced exponential growth in recent years in various applications [ 9 ]. Notable examples of these applications include wastewater treatment, biofuel production, hydrogen production, the production of high-value substances, the use of microalgae as biofertilizers in agriculture, as well as their use as food additives and in cosmetics [ 10 ].…”