Salt-affected soils severely decrease agricultural productivity by reducing the uptake of water and nutrients by plants, toxic ions accumulation and soil structure degradation. The sustainable synthesis of hybrid nanospheres through green approaches has emerged as an effective strategy to enhance crop productivity and improve tolerance to abiotic stress. However, the defensive functions and fundamental mechanisms of green synthesized calcium-doped carbon nano-spheres in protecting maize against salt stress remain elusive. Thus, calcium-doped carbon nanospheres were innovatively synthesized by doping calcium oxide nanoparticles (CaO NPs) with lignin nanoparticles (LNPs) which were further analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-Ray Spectroscopy (EDX), Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM). These analyses validated the successful doping of Ca@CNs, elucidating the purity and morphology of the hybrid nanospheres. More importantly, the effect of Ca@CNs on maize plants under NaCl stress, unreported so far, was examined. Results of the current study showed that treating salt-stressed plants with Ca@CNs significantly improved maize growth and biomass accumulation by enhanced absorption of minerals and improved photosynthetic efficiency. Furthermore, Ca@CNs application has also reduced NaCl-induced oxidative damage by enhancing antioxidant defense mechanisms and maintaining cellular integrity, resulting in improved resistance to salt stress. Moreover, Ca@CNs substantially up-regulated the expression of salt-tolerant genes ZmNHX3, CBL, ZmHKT1, and MAPK1, as well as genes involved in lignin biosynthesis such as 4CL2, PAL1, CCR, and COMT, in both shoot and root tissues. Conversely, the expression levels of genes Zm00001d003114, Zm0001d026638, Zm00001d028582 and Zm00001d051069 associated with Ca2 +-responsive SOS3 pathway were all down-regulated under NaCl treatment, while up-regulated in the presence of Ca@CNs along with NaCl. The observed changes in transcript levels of these genes highlight the potential of Ca@CNs in alleviating NaCl toxicity. These results demonstrated that the green synthetic Ca@CNs can significantly alleviate salt stress and promote plant growth in saline environments, which will provide a new strategy for the utilization of nanoparticles in agriculture to maintain sustainable agriculture and improve crop yield.

Seed priming and plant growth-promoting bacteria (PGPB) may alleviate salt stress effects. We exposed a salt-sensitive variety of melon to salinity following seed priming with NaCl and inoculation with Bacillus. Given the sensitivity of photosystem II (PSII) to salt stress, we utilized dark- and light-adapted chlorophyll fluorescence alongside analysis of leaf stomatal conductance of water vapour (Gsw). Priming increased total seed germination by 15.5% under salt-stress. NaCl priming with Bacillus inoculation (PB) increased total leaf area (LA) by 45% under control and 15% under stress. Under the control condition, priming (P) reduced membrane permeability (RMP) by 36% and PB by 55%, while under stress Bacillus (BS) reduced RMP by 10%. Although Bacillus inoculation (B) and priming (P) treatments did not show significant effects on some PSII efficiency parameters (FV/FM, ABS/RC, PIABS, FM), the BS treatment induced a significantly higher quantum efficiency of PSII (Phi PSII) and increased Gsw by 159% in the final week of the experiment. The BS treatment reduced electron transport rate per reaction center (ETO/RC) by 10% in comparison to the salt treatment, which showed less reaction centre damage. Bacillus inoculation and seed priming treatment under the stressed condition (PBS) induced an increase in electron transport rate of 40%. Salt stress started to show significant effects on PSII after 12 days, and adversely impacted all morphological and photosynthetic parameters after 22 days. Salt priming and PGPB mitigated the negative impacts of salt stress and may serve as effective tools in future-proofing saline agriculture.

Rising soil salinity hinders global crop yields by damaging plants, threatening food security. This study assessed glycine betaine (GB) application methods (foliar, seed priming) and salinity levels (0, 60, 120, 180 mM NaCl) on quinoa over two seasons. For ionic homeostasis, seed priming improved K+/Na+ ratio by 10-15 % at low salinity, while foliar was 12-18 % more effective at high salinity. Seed priming remained 10-15 % superior for roots. Foliar enhanced osmolytes by 12-16 % at low salinity, but seed priming had 16-20 % stronger effects at high salinity. Under low salinity, seed priming provided 8-12 % better protection for chlorophyll and photosynthetic efficiency. At high salinity, foliar GB was 10-15 % best for chlorophyll, seed priming 12-16 % more effective for photosynthetic rate, and foliar GB had an 8-10 % edge for Fv/Fm. GB reduced MDA by 8-12 % at low salinity, 12-16 % with seed priming at medium salinity in 2023, and 16-20 % with foliar in 2024. At high salinity, seed priming decreased MDA by 20-25 % in 2023, while foliar showed a 24-28 % reduction. GB moderately enhanced antioxidants by 8-12 % under mild stress, but seed priming and foliar differed 16-20 % in effectiveness under severe stress. For nutrients, seed priming had a 12-16 % advantage for nitrogen at medium salinity in 2023, while foliar excelled with a 16-20 % increase under high stress in 2024. Seed priming was 16-20 % better for phosphorus at high salinity in 2023, but foliar had 20-25 % superior results in 2024. These findings highlight complex plant responses to GB-salinity interactions, with optimal methods varying by trait, stress level, and environmental conditions. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Soil salinization poses a serious threat to sustainable ecological agricultural development. Most crops are susceptible to salt stress during the growth phase of seed germination and seedling emergence. Seed priming could activate the pre-germination metabolic processes, thereby improving seed germination and seedling growth under abiotic stress conditions. Moreover, multi-walled carbon nanotube (MWCNT), as an important class of carbon nanotubes, has been applied to promote plant growth by enhancing antioxidant defense systems and photosynthetic performance during the seedling stage. In this way, it is worth exploring the combination of pre-germination and post-germination treatments to reduce the damage of salt stress to crops. Therefore, in this study, rice seeds were firstly exposed to UV-B tube in a UV irradiation box for priming treatment (90 min). After emergence, the seedlings were transplanted into pots containing 150 mg L-1 MWCNT and 200 mM NaCl to evaluate the positive effects of nanomaterial on the growth of rice. The results demonstrated that after 28 days of salt stress exposure, the combination of UV-B priming and MWCNT significantly improved the growth performance of rice and minimized the adverse effects of salt stress, as compared with the single UV-B priming or MWCNT treatment, increasing biomass accumulation and the contents of osmoregulation substances, modulating antioxidant enzyme system, improving photosynthetic performance. This study suggested that the integration of seed priming with UV-B and soil application of MWCNT enhanced antioxidant capacity, which might increase photosynthesis and biomass accumulation, thereby improving the salt tolerance of rice.