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.