Applying biostimulants boosts forage productivity without affecting soil biotic and abiotic parameters on a Central Coast California rangeland

There is increasing interest in using biostimulant products, such as microbial inoculants and humic substances, to help manage rangelands regeneratively. Understanding how plant and soil communities on rangelands respond to these products is therefore important. In this study, we examined the combined effects of a commercial inoculant and humic product that are currently on the market, and asked whether they influenced rangeland forage productivity and quality, soil microbial biomass and community composition, and abiotic soil parameters in Central Coastal California. We found that forage productivity and some metrics of forage quality responded positively to the foliar application of a commercial microbial inoculant and humic product, but that these benefits were not mirrored by changes belowground in the microbial community or abiotic parameters. Depending on the goals of using the products, this could be seen as a winning scenario and suggests microbial inoculants and humic products could warrant attention as a potential tool for regenerative stewardship of rangelands. While our study derives from one ranch and therefore requires confirmation of its ubiquity prior to broadscale adoption, our results provide new insights into the usefulness of this approach for managing rangeland productivity in California's Central Coast.

Modulation of the Wheat Seed-Borne Bacterial Community by Herbaspirillum seropedicae RAM10 and Its Potential Effects for Tryptophan Metabolism in the Root Endosphere

Plants and their associated microbiota share ecological and evolutionary traits that are considered to be inseparably woven. Their coexistence foresees the use of similar metabolic pathways, leading to the generation of molecules that can cross-regulate each other’s metabolism and ultimately influence plant phenotype. However, the extent to which the microbiota contributes to the overall plant metabolic landscape remains largely unexplored. Due to their early presence in the seed, seed-borne endophytic bacteria can intimately colonize the plant’s endosphere while conferring a series of phytobeneficial services to their host. Understanding the dynamics of these endophytic communities is a crucial step toward the formulation of microbial inoculants that can modulate the functionality of the plant-associated microbiota for improved plant fitness. In this work, wheat (Triticum aestivum) roots non-inoculated and inoculated with the bacterium Herbaspirillum seropedicae strain RAM10 were analyzed to explore the impact of inoculant–endophyte–wheat interrelationships on the regulation of tryptophan (Trp) metabolism in the endosphere environment. Root inoculation with H. seropedicae led to phylum-specific changes in the cultivable seed-borne endophytic community. This modulation shifted the metabolic potential of the community in light of its capacity to modulate the levels of key Trp-related metabolites involved in both indole-3-acetic acid (IAA) biosynthesis and in the kynurenine pathway. Our results support a mode of action of H. seropedicae relying on a shift in both the composition and functionality of the seed-borne endophytic community, which may govern important processes such as root growth. We finally provide a conceptual framework illustrating that interactions among roots, inoculants, and seed-borne endophytes are critical to fine-tuning the levels of IAA in the endosphere. Understanding the outcomes of these interactions is a crucial step toward the formulation of microbial inoculants based on their joint action with seed-borne endophytic communities to promote crop growth and health in a sustainable manner.

Improvement in the Quality Attributes of Forage Cowpea by Use of Liquid Microbial Inoculants

Background: The present investigation was accepted to study the impact of liquid microbial inoculants on the quality parameters of forage cowpea (Vigna unguiculata). There upon, the field experiment was conducted during kharif 2018 at Punjab Agricultural University, Regional Research Station, Bathinda and at Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab respectively. Methods: The experiment was laid out in randomized complete block design with a total of eleven treatment combinations of liquid microbial inoculants (Burkholderia seminalis, Burkholderia sp. and Bradyrhizobium sp.) with 75% and 100% RDF and replicated thrice. The qualitative properties including crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), in-vitro dry matter digestibility (IVDMD), total soluble sugars and ash content were determined on the forage samples. Result: The results indicated that the treatment T10 (75% RDF + Burkholderia sp. + Burkholderia seminalis) has reduced ADF% and NDF% at both the locations. Forage with high ADF and NDF% content tends to have low digestibility, low ADF and NDF% is desirable. In addition, treatment T10 showed significantly (p less than 0.05) improved IVDMD (79.98%) and total sugars (15.82 mg/g) at Ludhiana and at Bathinda, T10 treatment significantly escalated crude protein (19.93%), total ash content (11.55%), total chlorophyll content (2.07 mg/g) and total sugars (15.80 mg/g).Further correlation studies showed highly significant positive correlation among ADF% and NDF% and there negative correlation with all other quality components at both the locations. Consequently, liquid microbial inoculants can play pertinent role in ameliorating fibre quality and interrelation between the various quality parameters proposed that forage with low ADF% and NDF% can be selected for simultaneous amelioration in different attributes of quality.

The Threat of Pests and Pathogens and the Potential for Biological Control in Forest Ecosystems

Forests are an essential component of the natural environment, as they support biodiversity, sequester carbon, and play a crucial role in biogeochemical cycles—in addition to producing organic matter that is necessary for the function of terrestrial organisms. Forests today are subject to threats ranging from natural occurrences, such as lightning-ignited fires, storms, and some forms of pollution, to those caused by human beings, such as land-use conversion (deforestation or intensive agriculture). In recent years, threats from pests and pathogens, particularly non-native species, have intensified in forests. The damage, decline, and mortality caused by insects, fungi, pathogens, and combinations of pests can lead to sizable ecological, economic, and social losses. To combat forest pests and pathogens, biocontrol may be an effective alternative to chemical pesticides and fertilizers. This review of forest pests and potential adversaries in the natural world highlights microbial inoculants, as well as research efforts to further develop biological control agents against forest pests and pathogens. Recent studies have shown promising results for the application of microbial inoculants as preventive measures. Other studies suggest that these species have potential as fertilizers.

A Holistic Approach for Enhancing the Efficacy of Soil Microbial Inoculants in Agriculture:

Microbial inoculants can be an efficient tool to manage the soil and plant microbiomes providing direct beneficial effects, and for modulating native soil and plant-associated microbiota. However, the application of soil microbial inoculants as biofertilizers and biopesticides in agriculture is still limited by factors related to their formulation, application method, and the knowledge about the impact and interactions between microbial inoculants and native soil and plant host microbiomes. The review is thus describing and discussing three major aspects related to microbial-based product exploitation, namely: i) the discovery and screening of beneficial microbial strains; ii) the opportunities and challenges associated with strain multifunctional features; iii) the fermentation and formulation strategies also based on the use of wastes as growth substrates and the technical and regulatory challenges faced in their path to field application. All these issues are addressed in activities performed by the EXCALIBUR project (www.excaliburproject.eu), which aims to expand the current concept about microbiomes interactions, acknowledging their interactive network that can impact agricultural practices as well as on all living organisms within an ecosystem.