The aim of this research was to evaluate whether the application of two plant growth-promoting (rhizo)bacteria might reduce nitrogen fertilization doses in cotton. We used strains Azotobacter chroococcum AC1 and AC10 for their proven ability to promote seed germination and cotton growth. These microorganisms were characterized by their plant growth-promoting activities. Then, we conducted a glasshouse study to evaluate the plant growth promoting ability of these strains with reduced doses of urea fertilization in cotton. Results revealed that both strains are capable of fixing nitrogen, solubilizing phosphorus, synthesizing indole compounds and producing hydrolytic enzymes. After 12 weeks, the glasshouse experiment showed that cotton growth was positively influenced due to bacterial inoculation with respect to chemical fertilization. Notably, we observed that microbial inoculation further influenced plant biomass (p<0.05) than nitrogen content. Co-inoculation, interestingly, exhibited a greater beneficial effect on plant growth parameters compared to single inoculation. Moreover, similar results without significant statistical differences were observed among bacterial co-inoculation plus 50% urea and 100% fertilization. These findings suggest that co-inoculation of A. chroococcum strains allow to reduce nitrogen fertilization doses up to 50% on cotton growth. Our results showed that inoculation with AC1 and AC10 represents a viable alternative to improve cotton growth while decreasing the N fertilizer dose and allows to alleviate the environmental deterioration related to N pollution.

Agri-food waste biomass (AWB) is consolidating as a relevant bioresource for supplying material products and energy in a circular bioeconomy. However, its recovery and sustainable processing present trade-offs that must be understood. The integration of multi-criteria decision analysis (MCDA) into life-cycle assessment (LCA) tools has emerged as a novel way to address this challenge. This paper aims to conduct a systematic literature review to critically synthesize how MCDA has been integrated into LCA in an assessment framework and how helpful it is in AWB’s circular bioeconomy transition. The literature shows that the most studied AWBs are rice husk, sugarcane bagasse, and household food waste. These are processed through the technologies of composting, anaerobic digestion, and pyrolysis for applications such as biofuels, bioenergy, and soil amendment. Environmental LCA (E-LCA) is the most widely used LCA tool, while both the analytical hierarchy process (AHP) and the technique for ordering preference by similarity to the ideal solution (TOPSIS) are the most applied techniques for MCDA. The current trend of integrating MCDA into LCA does not fully cover the LCA phases, favoring solely the impact assessment phase and indicating that the other phases are overlooked. The potential and involvement of the stakeholders are partially explored. Although there are holistic sustainability assessments, the social implications are rarely considered. The number of MCDA/LCA studies is expected to increase, assessments at the micro-, meso-, and macro-scales to become more articulated, and the impact of the results to become more aligned with government and company goals.

Drought is a global problem for crop productivity. Therefore, the objective of this research was to evaluate five dry-Caribbean Bacillus spp. strains in drought stress amelioration in maize plants. Maize seeds were single-strain inoculated and sown in pots under greenhouse conditions. After 12 days, plants were subjected to 33 days of drought conditions, i.e., 30% of soil field capacity, and then collected to measure leaf and root dry biomass, plant height, antioxidant enzymes, proline accumulation, and P+, Ca2+, and K+ uptake. Results correlated drought stress amelioration with the inoculation of Bacillus spp. strains XT13, XT38 and XT110. Inoculated plants showed increases in dry biomass, plant height, and K+ and P+ uptake. The overall maize antioxidant response to bacterial inoculation under drought stress showed dependence on proline accumulation and decreases in ascorbate peroxidase and glutathione reductase activities. Moreover, results suggest that this stress amelioration is driven by a specific plant-strain correlation observed in antioxidant response changes in inoculated plants under stress. Also, there is a complex integration of several mechanisms, including plant growth-promotion traits and nutrient uptake. Hence, the use of dry-Caribbean plant growth-promoting Bacillus strains represents an important biotechnological approach to enhance crop productivity in arid and semi-arid environments.

The circular economy (CE) has been proposed as a potentially significant catalyst to enhance the current response to the global climate crisis. The objective of this study was to investigate the scientific literature of the research between climate change and CE adopting a knowledge mapping approach. Based on a total of 789 peer-reviewed publications extracted from Scopus, we found that research on climate change and CE is continually growing and interdisciplinary in nature. Europe notably leads scientific production. Keyword evolution shows that CE has been influenced by more lines of research than climate change. We also found that waste management is the CE approach most associated with climate change, mitigation is the climate action most impacted by CE, and food is the most reported greenhouse gas (GHG)-emitting material. However, there are knowledge gaps in the integration of the social dimension, the promotion of climate change adaptation, and the association of sustainable development goal (SDG) 13. Finally, we identified four potentially valuable directions for future studies: (i) CE practices, (ii) bioeconomy, (iii) climate and energy, and (iv) sustainability and natural resources, in which carbon recovery technologies, green materials, regional supply chains, circular agriculture models, and nature-based solutions are promising themes.

Phosphate-solubilizing bacteria represent a bioalternative in making soil-immobilized phosphorus (P) available to plants, and consequently improve agriculture sustainability and reduce nutrient pollution. In this study, we examined whether Rhizobium sp. B02 inoculation can affect the soil P fractions. Moreover, we investigated how inoculation influences the growth, physiological traits, and productivity of the maize crop. Field tests were carried out to evaluate the combined application of strain B02 and reduced doses of P fertilizer. Soil P fractionation was performed after crop harvesting, assessing the P dynamics. To study the plant response, samplings were carried out in three phenological stages—the vegetative stage of the 7 fully emerged leaves with leaf collars (V7), the vegetative stage of the tassel (VT), and the reproductive stage of physiological maturity (R6). Using 50% of P fertilizer recommended, the strain inoculation increased the labile inorganic P fraction by 14% compared to the control treatment at the same dose, indicating that it favored the Pi mobility. Under these same conditions in the V7 and VT phenological stages, the inoculation significantly improved shoot length (28 and 3%) and shoot dry weight (9.8 and 12%). B02 inoculation increased grain yield by 696 kg ha⁻¹ using 50% of the recommended rate of P fertilizer, phenocopying the complete P fertilization treatment without inoculation. Therefore, Rhizobium sp. B02 inoculation replaced 50% of P fertilizer in maize and increased the soil P availability.