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Despite the wide utilization of chitosan nanoparticles (CSNPs) as a promising approach for sustainable agriculture, their efficiency under elevated CO 2 (eCO 2 ), has not been evaluated. The interactive effects of CSNPs and eCO 2 were evaluated on the growth and C and N metabolism of soybean plants. Plants were treated with CSNPs and grown under ambient CO 2 (410 ppm, aCO 2 ) or eCO 2 (645 ppm). Regardless of CO 2 level, CSNPs improved the net photosynthetic rate. CSNPs aggravated the effect of eCO 2 treatment on the levels of non-structural carbohydrates (i.e., glucose, fructose, sucrose, and starch), especially in shoots, which was inconsistence with the upregulation of carbohydrates metabolizing enzymes. Being the most pivotal energetic and signaling organic compounds in higher plants, the synergistic action of CSNPs and eCO 2 on the accumulation of soluble sugars upregulated the N metabolism as indicated by induced activities of nitrate reductase, arginase, glutamate dehydrogenase, glutamine synthetase, and glutamine oxoglutarate aminotransferase which was manifested finally as increased shoot and root total nitrogen content as well as proline and aspartate in roots. At the hormonal level, the coexistence of eCO 2 with CSNPs further supports their positive impact on the contents of IAA and, to a lesser extent, GAs. The present data prove that the biofertilization capacity of CSNPs is even more potent under futuristic eCO 2 levels and could even further improve the growth and resilience of plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Arbuscular mycorrhizae fungi (AMF) symbiosis is an indispensable approach in sustainable agriculture. AMF-plant association is likely to be enhanced by the nanoparticle's application. Herein, the impact of chitosan nanoparticles (CSNPs) on the mycorrhizal colonization in wheat has been investigated. The provoked changes in wheat growth, physiology and metabolism were assessed. CSNPs treatment improved AMF colonization (52 %) by inducing the levels of auxins and strigolactones in roots by 32 and 21 %, respectively besides flavonoids exudation into the rhizosphere (9 %). Such supporting action of CSNPs was associated with improved plant biomass production (21 %) compared to AMF treatment. Both treatments synergistically enhanced the photochemical efficiency of photosystem II and stomatal conductance, therefore the photosynthetic rate was increased. The combined application of CSNPs and AMF enhanced accumulation of glucose, fructose, sucrose, and starch (12, 22, 31 and 13 %, respectively), as well as the activities of sucrose-p-synthase, invertases and starch synthase compared to AMF treatment. The synchronous application of CSNPs and AMF promoted the levels of polyphenols, carotenoids, and tocopherols therefore, improved antioxidant capacity (33 %), in the roots. CSNPs can be applied as an efficient biofertilization strategies to enhance plant growth and fitness, beside improvement of health promoting compounds in wheat., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

With the objective of studying the influence of elicitors on the growth, yield, and quality of kalmegh, we carried out an investigation for two consecutive years. Nine treatments with three replications were laid out in a completely randomized design (CRD). Chitosan (CHT), yeast extract (YE), jasmone acid (JA), and salicylic acid (SA)were evaluated at different concentrations. The CHT treatment at 1000 ppm exhibited the tallest plant height (73.91 cm) and the highest number of secondary branches (29.07) at the time of harvest. The primary branches and number of leaves per plant were highest with the CHT treatment at 1000 ppm (26.36; 88.32), and were not significantly different with the SA treatment at 200 ppm (26.28; 81.51). The plant spread was the highest with the SAtreatment at 200 ppm (35.46 cm2) and was not significantly different with the CHT treatment at 1000 ppm (35.11 cm2). The CHT and SA sprays did not result in significant changes in yield parameters, but the highest fresh (42.34 g) and dry (18.30) herbage yields per plant were exhibited with the SA treatment at 200 ppm. The highest total chlorophyll (4.459 mg g−1) and total andrographolide (3.494%) contents were recorded after treatment with the SA spray at 200 ppm. A significant and positive improvement in the growth, yield, and quality of kalmegh was noticed with the salicylic acid spray treatment at 200 ppm 30 and 60 days after sowing (DAS), signifying its benefits for the cultivation of kalmegh in terms of high productivity, quality, and better returns for farmers. [ABSTRACT FROM AUTHOR]