Search

Microbiome-based rhizospheric engineering has emerged as a promising approach towards attaining agricultural sustainability. While the top-down approach of acclimatizing the rhizospheric microbiome to stressors is relatively easy to perform, the mechanisms involved in plant growth promotion by directed evolution are yet to be understood. The present study aimed to understand the mechanism of stress management by a salt stress-acclimatized microbiome, generated through indirect plant-mediated selection over multiple plant (Vigna radiata) growth cycles, with a focus on the emission of volatile compounds. A culture bank was generated by isolation of bacterial strains from the stress-acclimatised microbiome, using group-specific media. Characterization of the strains was performed by examining their potential plant growth-promoting (PGP) traits followed by phylogenetic affiliation using 16S rRNA sequencing. The strains exhibited strong tolerance to salinity stress when grown on artificial root exudate medium and V8 medium, at different salt concentrations. Based on PGP scoring, the eleven best performing bacterial strains were assessed for their ability to impact plant morphology and growth attributes in a split plate assay allowing only volatile compounds to be exchanged, using Arabidopsis as a model plant. An alteration in the seedling morphology of Arabidopsis was observed due to the production of volatile bioactive compounds by some of the strains. To delineate the specific volatiles produced by the bacterial strains responsible for such an impact on Arabidopsis seedlings, the volatiles emitted by selected strains were collected and analyzed by GC-MS. A correlation could be drawn between the specific volatiles produced by key bacterial members of the acclimatized microbiome e.g. Bacillus haynesii, Pseudomonas monteilii and Ochrobactrum soli , and their contribution towards alleviation of salinity stress in A. thaliana. A detailed analysis of the volatilomes emitted by stress-acclimatized bacterial strains revealed the identity of crucial metabolites, for instance hydrocarbons like 7 methyl-hexadecane, 2-(2-butoxyethoxy) ethanol or sulfur containing volatiles, which could at least partially contribute to plant growth promotion and stress tolerance. This work opens up new avenues for rhizospheric engineering as a way towards more resilient and sustainable crop production. • Mode of action of engineered microbiome in stress mitigation revealed. • Strains with multi-PGP traits were identified from stress-acclimatized microbiome. • Bacteria exhibited salinity stress tolerance and growth promotion in Arabidopsis. • Volatiles' importance in stress mitigation by acclimatised microbiome highlighted. • Key volatiles mediating growth promotion and stress tolerance were identified. [ABSTRACT FROM AUTHOR]

The world population and consequently the global need for food continue to grow. At the same time, areas will be used to generate clean electricity to cope with climate change and global warming. The combination of crop production and solar photovoltaics in the form of "agrivoltaic technology" offers advantages for both sides that provide an adequate, resource-efficient solution to the persistent problem of competition for arable lands. The implementation of agrivoltaic systems has been exponentially increased in recent years and reached the global installed capacity of 2.8 GW in 2020 from the initial capacity of 5 MW in 2012. The agrivoltaic systems installed worldwide mostly employ conventional opaque photovoltaic (PV) modules, causing a change in the microclimate under the panels that become critical when shading ratios are high. Semi-transparent PV (STPV) modules have been recently employed to mitigate this issue which is profoundly studied in this research by considering the use of semi-transparent technologies based on crystalline silicon (c-Si), thin-film photovoltaics, organic PVs (OPVs), dye-sensitized solar cells (DSSCs), concentrating PVs (CPVs), and luminescent solar concentrators (LSCs) in open (arable farming lands) and closed (cultivation greenhouses) agrivoltaic systems. The results indicated that c-Si STPV modules have the highest share of employment in agrivoltaic systems due to their extreme benefits of low costs, high stability, and high efficiency in comparison with other technologies, while in contrast, the use of thin-film STPV modules have been rarely reported in the literature. Additionally, STPV modules using OPVs and DSSCs offer the capability to achieve wavelength-selective transparency, causing the photosynthetic active radiation to pass through while the remained spectrum is utilized to generate electricity. Other potential solutions come from CPVs and LSCs, in which, diffuse light is available for the growth of cultivated plants, while direct concentrated sunlight can generate electricity. Although STPV modules are proven as a feasible solution for use in agrivoltaic systems, still more developments are required in terms of the modules' efficiency enhancement and costs reduction, while more detailed research is required to observe the response of cultivated plants to make this technology a viable sustainable solution in the future. • Semi-transparent photovoltaic modules can mitigate shading in agrivoltaic systems. • Thin-film semi-transparent modules are promising for use as roofs of greenhouses. • Dye-sensitizes cells are flexible, lightweight, and can work under diffuse sunlight. • Wavelength selective transparency allows photosynthetic active radiation to pass. • In concentrating photovoltaic, diffuse light is available for the growth of plants. [ABSTRACT FROM AUTHOR]

The world population and consequently the global need for food continue to grow. At the same time, areas will be used to generate clean electricity to cope with climate change and global warming. The combination of crop production and solar photovoltaics in the form of "agrivoltaic technology" offers advantages for both sides that provide an adequate, resource-efficient solution to the persistent problem of competition for arable lands. The implementation of agrivoltaic systems has been exponentially increased in recent years and reached the global installed capacity of 2.8 GW in 2020 from the initial capacity of 5 MW in 2012. The agrivoltaic systems installed worldwide mostly employ conventional opaque photovoltaic (PV) modules, causing a change in the microclimate under the panels that become critical when shading ratios are high. Semi-transparent PV (STPV) modules have been recently employed to mitigate this issue which is profoundly studied in this research by considering the use of semi-transparent technologies based on crystalline silicon (c-Si), thin-film photovoltaics, organic PVs (OPVs), dye-sensitized solar cells (DSSCs), concentrating PVs (CPVs), and luminescent solar concentrators (LSCs) in open (arable farming lands) and closed (cultivation greenhouses) agrivoltaic systems. The results indicated that c-Si STPV modules have the highest share of employment in agrivoltaic systems due to their extreme benefits of low costs, high stability, and high efficiency in comparison with other technologies, while in contrast, the use of thin-film STPV modules have been rarely reported in the literature. Additionally, STPV modules using OPVs and DSSCs offer the capability to achieve wavelength-selective transparency, causing the photosynthetic active radiation to pass through while the remained spectrum is utilized to generate electricity. Other potential solutions come from CPVs and LSCs, in which, diffuse light is available for the growth of cultivated plants, while direct concentrated sunlight can generate electricity. Although STPV modules are proven as a feasible solution for use in agrivoltaic systems, still more developments are required in terms of the modules' efficiency enhancement and costs reduction, while more detailed research is required to observe the response of cultivated plants to make this technology a viable sustainable solution in the future. • Semi-transparent photovoltaic modules can mitigate shading in agrivoltaic systems. • Thin-film semi-transparent modules are promising for use as roofs of greenhouses. • Dye-sensitizes cells are flexible, lightweight, and can work under diffuse sunlight. • Wavelength selective transparency allows photosynthetic active radiation to pass. • In concentrating photovoltaic, diffuse light is available for the growth of plants. [ABSTRACT FROM AUTHOR]