Introduction

Conventional agriculture is large-scale agriculture that widely uses artificial fertilizers, herbicides, and pesticides (Razanakoto et al. 2021). As an alternative, sustainable agriculture is fixed on management planes addressing the main societal worries about food quality or environmental protection. It involves two approaches: 1) agriculture should keep itself over a long period by conserving its productive resources, such as soil fertility maintenance, protection of groundwater, development of renewable energies, and detection solutions for acclimating farming systems to variations of climate; 2) agriculture systems should aid the sustainability of large domains and social societies (Lichtfouse et al. 2009). Nowadays, without reducing the yield and quality of crops, the agricultural systems should apply minimum inputs and resources to attain economic advantagability, environmental security and social justice (Le Bail et al. 2005). During the past ten years, the world population has considerably enhanced and is envisaged to attain around 9.5 billion by 2050 (Singh et al. 2016). Therefore, given the growing global population, achieving global food security is possible through the design of advanced agricultural systems that can maximize our productivity and production with the minimum input required (Berg 2009). The additions contain phosphorus and nitrogen as fertilizer and pesticides as biocontrol agents for invasive weeds, pathogens, and insects. To increase or maintain crop yield, the farmers can benefit from new sustainable products, such as plant beneficial microorganisms (PBM) (Baulcombe et al. 2009).
The soils are considered the densest and most diverse microbial habitats of plants (Fierer and Jackson 2006). Plant roots interact closely with soil micro-organisms. Complex interactions between roots and their related microbiomes are key factors in plant health (Mauchline and Malone 2017). The soil-borne pathogens limit and reduce plant growth, while the association of plants with PBM can promote plant growth. These PBM can facilitate plant nutrient uptake or increase stress tolerance (Pieterse et al. 2016). In addition, they can protect plants against pathogens through antagonism, competition, and stimulation of the plant’s immune system (Pieterse et al. 2016). PBM include rhizobia associated with legumes and mycorrhizal fungi, as well as other free-living plant growth-promoting bacteria (PGPB) and fungi (PGPF) that and fungi (PGPF) that benefit a broad variety of plant species (Berendsen et al. 2015). PBM can increase plant growth, facilitate water and nutrient uptake and distribution through different mechanisms (Allen 2009). For example, mycorrhizal symbiosis in soils may help to absorb and transfer water and nutrients through hyphae from the outer mycelium (Maurel and Chrispeels 2001). PGPB can help establish a root system and enhance plant growth by synthesizing bioactive substances such as phytohormones (e.g., auxins, gibberellins, and cytokinins), siderophore, and 1-aminocyclopropane-1-carboxylase (ACC) deaminase (Maurel and Chrispeels 2001). Moreover, nitrogen fixation through PBM occurs in free-living or non-coexistence (e.g., Azotobacter ), coexistence (e.g.,Rhizobium ), and cooperation (e.g., Azospirillum ) forms (Malusá et al. 2012, Rocha et al. 2019a).
In the 1930s, the first seed coating artificial on cereal seeds was inspired by the pharmaceutical industry, and thereafter the using large-scale commercial of this tool started in the 1960s (Kaufman 1991). Nowadays, this tool was availed worldwide in horticultural and crop industries (Rocha et al. 2019a). In the artificial seed coating, different materials (e.g., biopolymers, colorants, biocontrol agents, and microbes) are used in coating the surface of seeds (Piri et al. 2019, Rocha et al. 2019a) to correct the physical features of seed crops and vegetable species, turfgrass, pasture, and flowers via deformation of seed weight and size (Afzal et al. 2020). The function of seed coating according to its mode of action or properties includes protecting plants, reducing environmental stress, or improving plant growth (Amirkhani et al. 2016). Indeed, seed coating is used as a biological tool that improves follow ability for agricultural sustainability (Piri et al. 2019, Rocha et al. 2019a). Considering these advantages, nowadays the application of this tool has been proposed for seed inoculation in different plants since it can use partial rates of inocula in a precise use (Rouphael et al. 2017). Hereby, the purpose of this study is to examine microbial seed coatings and their significance for sustainable agriculture.