The Use of Microalgae and Cyanobacteria in the Improvement of Agricultural Practices: A Review on Their Biofertilising, Biostimulating and Biopesticide Roles

Abstract

The increase in worldwide population observed in the last decades has contributed to an increased demand for food supplies, which can only be attained through an improvement in agricultural productivities. Moreover, agricultural practices should become more sustainable, as the use of chemically-based fertilisers, pesticides and growth stimulants can pose serious environmental problems and lead to the scarcity of finite resources, such as phosphorus and potassium, thus increasing the fertilisers’ costs. One possible alternative for the development of a more sustainable and highly effective agriculture is the use of biologically-based compounds with known activity in crops’ nutrition, protection and growth stimulation. Among these products, microalgal and cyanobacterial biomass (or their extracts) are gaining particular attention, due to their undeniable potential as a source of essential nutrients and metabolites with different bioactivities, which can significantly improve crops’ yields. This manuscript highlights the potential of microalgae and cyanobacteria in the improvement of agricultural practices, presenting: (i) how these photosynthetic microorganisms interact with higher plants; (ii) the main bioactive compounds that can be isolated from microalgae and cyanobacteria; and (iii) how microalgae and cyanobacteria can influence plants’ growth at different levels (nutrition, protection and growth stimulation).

Biopesticides in Sustainable Agriculture: A Critical Sustainable Development Driver Governed by Green Chemistry Principles

“…They are categorized into three groups: microbial biopesticides, biochemical biopesticides, and PIPs (Leahy et al, 2014;Liu et al, 2019;Ram and Singh, 2021). Bacillus thuringiensis (Bt) control 90% of the microbial biopesticide market; however, Beauveria bassiana, Baculovirus, Steinernema, Nosema, and Chlorella have also demonstrated significant roles (Steinkraus and Tugwell, 1997;Abu-Dieyeh and Watson, 2007;Radwan et al, 2018;Gonçalves, 2021). Biochemical biopesticides are compounds (or exact synthetic analog) of natural origin possessing active ingredients that control pest by mechanisms that are nontoxic to the target pest, the environment and humans (Kumar, 2012;Reddy and Chowdary, 2021).…”

Seaweed and microalgae as major actors of blue biotechnology to achieve plant stimulation and pest and pathogen biocontrol – a review of the latest advances and future prospects

“…Abiotic stresses adversely affect growth, productivity and trigger a series of morphological, physiological, biochemical and molecular changes in plants. A direct link between seaweed/microalgae and these parameters can be done, ensuring real interest in the use of these bioproducts in order to stabilize potential financial losses (Gonçalves, 2021). The effects of germination parameters ( percentage index, mean time) and growth parameters (shoot and root length) of mung bean (Vigna radiata) treated with acid seaweed liquid of Ulva latucta extracts at 0.2% were evaluated by Castellanos-Barriga et al (2017).…”

“…Their ethanol extract of Sargassum wightii presented larvicidal activity against Aedes aegypti (dengue and Zika virus vector). Another insect problem, the Asian citrus psyllid Diaphorina citri, has been controlled by repellent and insecticidal effects of ethanolic extracts obtained from Caulerpa sertularioides, Laurencia johnstonii and Sargassum horridum seaweeds (González-Castro et al, 2019). A recent example of success against nematodes is the use of three microalgae (Scenedesmus obliquus, Chlorella vulgaris and Anabaena oryzae), alone or in combination, to control the root-knot nematode Meloidogyne incognita.…”

“…A variety of endophytic bacteria and free-living rhizobacteria on the root surface and rhizosphere utilize the nutrients released from the host, as well as secrete metabolite substances to the soil that aid in controlling plant diseases caused by fungi or bacteria. Besides, microalgae, especially cyanobacteria, are able to biosynthesize a number of secondary metabolites with potential biopesticidal action and can be considered potential biological agents for the control of harmful organisms to soils and plants (Costa et al ., 2019; Gonçalves, 2021). These activities are attributed to phenolic compounds, polyphenols, tocopherols, saponins, nitrogen-rich peptides and sesquiterpenes.…”

Nitrogen Deficiency in Culture Affects the Metabolic Pathways in Amphora Coffeaeformis for Biodiesel Production

“…Microalgae have become one of the alternative raw materials for biofuel production due to their high carbohydrate and fat content, fast growth rate, and strong resistance to the environment [2,3]. Reports have shown that the photosynthetic productivity of microalgae is several folds higher than that of higher plants, which also increases the fatty acid synthesis in certain microalgae [4,5]. Furthermore, microalgae can also resolve the problem of land competition between traditional oil crops and food crops.…”