Plant Growth Promoting Rhizobacteria: Mechanism and Current Prospective

Abstract

Despite the phytotoxicity of olive-mill solid waste (OMSW) due to its high polyphenols content, OMSW have fertilizer characteristics, which make it a potential source for organic fertilization. Composting of OMSW treatment process was conducted in this study to eliminate the phytotoxicity and solve the environmental impact of this waste. Recycling of OMSW was carried out via composting of six batches of trials using equal proportions of OMSW, cow manure (C) and wheat straw (W). The treatment process was performed at two time intervals (two and five months), after each one, the recipient species (Vicia faba L.) was planted. The results showed the efficiency of composting in reducing OMSW original toxicity after two months than five months. The germination percentage and the plumule and radicle lengths of V. faba showed a significant improvement when the OMSW was composted with C at different proportions before using as soil amendments. Besides, the total biomass was noticeably increased at the high concentration of C-OMSW. Similarly, the total pigments concentration in V. faba was increased by using various composts after two months, where the highest pigment content was observed at 40% W-OMSW treatment.

Bacteria-Plant interactions: an added value of microbial inoculation

“…In recent years there has been a need for food production to increase due to the rise in growth population, generating a permanent concern for farmers to maintain soil fertility (Kundan et al 2015). To satisfy the food demand, farmers have adopted an indiscriminate use of chemical products that endanger public and environmental health (Alori et al 2017).…”

“…They can affect plant growth through direct and indirect mechanisms (Ngoma et al 2012). Direct mechanisms are related with a forward and a direct promotion of plant growth (Kudan et al 2015); while indirect involves the ability of PGPB to diminish negative effects of phytopathogens (Grobelak et al 2014, Zúñiga et al 2019. These include bacteria assistance for plant nutrient acquisition, modulation of phytohormones levels, production of antimicrobial compounds against phytopathogenic microorganisms, induction of systemic resistance against pathogens and competition ability, among others (Eida et al 2018).…”

A preview of perennial grain agriculture: knowledge gain from biotic interactions in natural and agricultural ecosystems

“…Among cereal crops, bacteria with effective disease control properties were identified from the rhizosphere of wheat, barley, maize, and sorghum (Kundan et al. ). Other mechanisms involved in disease suppression include the activation of plant defense mechanisms, known as induced systemic resistance (ISR).…”

“…As alternative to chemical control, rhizospheric microorganisms that suppress plant pathogens could be used as biocontrol agents, which produce antibiotics, toxins, and hydrolytic enzymes that degrade virulence factors or pathogen cell wall components (Compant et al 2005, Pereg andMcMillan 2015). Among cereal crops, bacteria with effective disease control properties were identified from the rhizosphere of wheat, barley, maize, and sorghum (Kundan et al 2015). Other mechanisms involved in disease suppression include the activation of plant defense mechanisms, known as induced systemic resistance (ISR).…”

Survival of Microbial consortium in granular formulations, degradation and release of microorganisms in soil

“…Phosphate solubilizing Bacteria (PSB) plays a major role in the solubilization and uptake of native and applied soil P (Krishnaveni, 2010). The term "plant growthpromoting-rhizobacteria" (PGPR) has been coined to encompass bacteria with plant growth stimulating activity resulting from several mechanisms (Kundan 2015). The production of plant growth stimulating hormones and the suppression of minor plant pathogens by various mechanisms have been suggested to represent the main activities of PGPR.…”