Potential Use of Beneficial Microorganisms for Soil Amelioration, Phytopathogen Biocontrol, and Sustainable Crop Production in Smallholder Agroecosystems

Abstract

Smallholder agroecosystems play a key role in the world's food security providing more than 50% of the food produced globally. These unique agroecosystems face a myriad of challenges and remain largely unsupported, yet they are thought to be a critical resource for feeding the projected increasing human population in the coming years. The new challenge to increase food production through agricultural intensification in shrinking per capita arable lands, dwindling world economies, and unpredictable climate change, has led to over-dependence on agrochemical inputs that are often costly and hazardous to both human and animal health and the environment. To ensure healthy crop production approaches, the search for alternative ecofriendly strategies that best fit to the smallholder systems have been proposed. The most common and widely accepted solution that has gained a lot of interest among researchers and smallholder farmers is the use of biological agents; mainly plant growth promoting microorganisms (PGPMs) that provide essential agroecosystem services within a holistic vision of enhancing farm productivity and environmental protection. PGPMs play critical roles in agroecological cycles fundamental for soil nutrient amelioration, crop nutrient improvement, plant tolerance to biotic and abiotic stresses, biocontrol of pests and diseases, and water uptake. This review explores different research strategies involving the use of beneficial microorganisms, within the unique context of smallholder agroecosystems, to promote sustainable maintenance of plant and soil health and enhance agroecosystem resilience against unpredictable climatic perturbations.

Effects of Abiotic Stress on Soil Microbiome

“…Conventional farming on the other hand depends heavily on the utilization of high input modern agriculture that employs chemical pesticides and synthetic fertilizers [214]. Considering that the microbiome is involved in nearly every soil activity, and microbial composition, diversity, abundance, and activity will primarily enhance crop health and long-term productivity of agricultural land [215]. Thus, it is critical to maintain the microbiome in outstanding shape in order to preserve the long-term viability of the land.…”

“…Microbial inoculants particularly plant growth promoting microorganism (PGPM) is one of the most efficient soil bacteria for promoting plant growth and development [215,263]. PGPM can benefits plants in three mechanisms: (i) Biofertilizer (i.e., N 2 -fixing bacteria and phosphate-solubilizing bacteria) to aid in plant nutrient absorption by delivering fixed nitrogen or other nutrients [264]; (ii) Phytostimulators that can stimulate plant growth by creating plant hormones [264][265][266]; and (iii) Biological control agents to protect from phythopathogenic organisms and abiotic stress [264].…”

Competency of Rhizobial Inoculation in Sustainable Agricultural Production and Biocontrol of Plant Diseases

“…The growth rate of the global human population increases alarmingly, demanding a substantial increase in food production. This increase in demand for food needs to be fulfilled using the current arable land, which is currently under stress from an increasing human population, harsh climatic conditions, degradation in soil fertility and health, and emerging and re-emerging diseases (Koskey et al, 2021). In this context, harnessing agricultural resources such as legumes and legume-incorporating production approaches can play an imperative role by providing manifold services harmonized with sustainability issues (Stagnari et al, 2017;Kebede, 2020a).…”

“…On the other hand, modern agriculture is facing critical challenges in which chemical fertilizers are utilized to attain higher crop yield while enhancing negative ecological impacts (Tariq et al, 2020;Koskey et al, 2021;Yadav et al, 2021). Hence, the uses of inoculants are key approaches along with their recognized achievements of crop yield improvement and biocontrol of plant diseases (Yadav et al, 2021).…”

“…The use of rhizobial inoculants can be, thus, emphasized as one of the best approaches for sustainable agricultural production and a feasible solution to sustain the twin problems of global food security and environmental stability (Tariq et al, 2020;Yadav et al, 2021). This approach is important, particularly in the developing world where much of the increases in food production come from the need to feed an alarmingly increasing population (Koskey et al, 2021). As a result, the documentation of available information on the potential of rhizobia in improving crop productivity and providing resistance against plant diseases will be beneficial for the endorsement of this approach and the development of sustainable agricultural systems.…”