Drought (D) and chromium (Cr) stress co-occur in agricultural fields due to the accumulation of excessive Cr in soils from industrial pollution and increasing frequency of water scarcity. Carrageenan (Car), a compound extracted from red seaweed, is an emerging biostimulant with multifaceted roles in plants. This study investigated the role of exogenous Car in mediating tolerance to D-, Cr-, and DCr-stress in wheat seedlings, aiming to elucidate the potential of Car in mitigating toxicity and promoting plant resilience. Wheat seedlings exposed to DCr-stress exhibited reduced growth and biomass production, along with elevated levels of reactive oxygen, carbonyl, and nitrogen species. Moreover, D-stress exacerbated Cr-toxicity, as demonstrated by principal component analysis (PCA), which showed a strong positive correlation between DCr-stress and stress marker parameters. This suggests that DCr-stress resulted in higher Cr uptake and increased oxidative damage compared to individual D-or Cr-stress, making DCr-stress more detrimental than either stress applied alone. However, Car priming ameliorated the toxic effects of DCr-stress and promoted the growth performance of DCr-stressed wheat seedlings. In PCA, the positive correlation of D + Car, Cr + Car, and DCr + Car treatments with growth and plant defense-related parameters suggests that Car-mediated improvement in stress tolerance can be attributed to reduced accumulation of toxic Cr, increased levels of total free amino acids and soluble sugars, enhanced antioxidant enzyme activity, elevated non-enzymatic antioxidant levels, higher phenolic and flavonoid content, and improved metal chelation and detoxification. Our results indicated Car is a potential and cost-effective biostimulant for managing D-, Cr-, or DCr-stress in wheat.

In the arid and semi-arid zones of Northwest China, soil drought and alkaline salt stress often occur simultaneously and affect plant growth at multiple levels. Potato (Solanum tuberosum L.) is a food crop sensitive to drought and alkaline salt stresses and is susceptible to yield loss due to environmental impacts. In recent years, most of the research on abiotic stress response in potato has focused on drought and saline single stresses, and the mechanism of potato response to combined drought-alkaline salt stress and its interactions are still unclear. Therefore, a pot experiment was designed in this study and the potato variety 'Atlantic' was selected as the test material. The effects of drought (25 % PEG-6000), alkaline salt (200 mmol & sdot;L-1 NaHCO3) and combined drought- alkaline salt (25 % PEG-6000 + 200 mmol & sdot;L-1 NaHCO3) stresses on growth traits, micro- and ultrastructure, reactive oxygen species, osmoregulatory substances, and antioxidant defenses of potato were investigated using no stress (CK) as a control, leaf photosynthesis and endogenous plant hormones, and also analyzed the changes in the expression patterns of genes related to plant hormone signal transduction under different stresses. The results showed that drought, alkaline salt, and combined stress affected growth, leaf anatomy, and photosynthesis, and increased the accumulation of osmoregulatory substances in potato. The scavenging activities of antioxidant compounds and antioxidant enzymes were enhanced in potato, and combined stress treatments significantly damaged potato more than single stresses. In 2022, combined stress caused a marked increase in H2O2 (208.7 %) and O2- (455.6 %) content, while in 2023, they increased by 87.5 % and 215.7 %, respectively. SOD, POD, CAT, TPX, APX, GR, GPX and DHAR enzyme activities were increased by 209.13 %, 55.19 %, 152.59 %, 47.13 %, 104.02 %, 347.37 %, 68.45 % and 130.69 % in 2022 compared to CK in the combined stress treatment. In 2023, they increased by 229.81 %, 49.95 %, 160.62 %, 102.16 %, 94.06 %, 505.15 %, 47.00 %, and 121.19 %, respectively. After the stress treatments, the contents of gibberellic acid (GA3) and auxins (IAA) were significantly lower than those in CK, whereas the contents of abscisic acid (ABA), salicylic acid (SA), and brassinosteroids (BRs) increased. Expression of IAA-related genes (AUX1, Aux/IAA, GH3, and SAUR) was up-regulated after stress. ABA-related genes (PYR/PYL, SnRK2, and ABF) were up-regulated after stress, whereas protein phosphatase 2C (PP2C) genes were down-regulated in expression after stress. The GA3 receptor GID1 and the Fbox protein GID2 were up-regulated after stress. Xyloglucosyl transferase TCH4 gene was up-regulated by stress and positively correlated with changes in BRs content. The TGA transcription factor, PR-1 gene, was induced to up-regulate its expression by stress and positively correlated with changes in SA content. Drought, alkaline salt, and combined stress reduced potato tuber yield and quality, which were 54.13 % and 60.14 % lower than CK in combined stress treatments in 2022 and 2023, respectively, which were significantly correlated with changes in physiological and biochemical characteristics and hormone contents of potato plants.

Diesel spills and nuclides pollution cause global ecosystem and human health problems. The remediation of contaminated soil using woody plants has received considerable attention. Differences in plant species and sex can lead to differences in tolerance to various stressors. We aimed to investigate the response of male and female seedlings of Populus cathayana and Salix babylonica to diesel and Sr2+ stress and to compare the enrichment characteristics of Sr2+ in trees. Male and female seedlings of P. cathayana and S. babylonica were treated with diesel fuel and 0, 10 (low), and 100 (high) mg Kg(-1) of Sr2+. Results showed that P. cathayana and S. babylonica had good enrichment characteristics and tolerance. S. babylonica had a more robust tolerance and ability to remediate contaminated soil than P. cathayana. The defense mechanisms of both female seedlings in response to stress were similar, while males showed different defense strategies. Male trees had higher Sr2+ enrichment capacity, antioxidant enzymes, soil enzyme activity, and soluble matter content, indicating that males had higher tolerance capacity than females. Under diesel stress alone, the reduced photosynthetic rate of male seedlings of P. cathayana was mainly limited by stomatal factors, and their photosynthetic system was more tolerant to diesel. POD and APX activities, as well as alkaline phosphatase and urease activities in the soil, were significantly higher in S. babylonica seedlings than in P. cathayana, indicating that S. babylonica seedlings were more resistant to diesel pollution. At low concentrations of the Sr2+ complex, diesel and Sr2+ showed antagonistic effects in reducing the damage caused by stress. As the Sr2+ concentration increased, damage to the plants manifested primarily through synergistic enhancement. The results of this study provide a scientific basis for the remediation of diesel fuel and nuclides contaminated soils using woody plants.

Crops are often affected by NaCl, giant ragweed (Ambrosia trifida L.) and freeze-thaw stress simultaneously during their growth, and many areas in Northeast China are facing such serious ecological stress problems. In this experiment, the physiological responses of rye seedlings to NaCl and A. trifida extract stressor (AES) in a freeze-thaw environment were studied by artificial simulation technique. Malondialdehyde net photosynthetic rate (Pn) and transpiration rate (Tr) were determined and analyzed. The results showed that: After stress treatment, MDA and SP contents of rye seedlings increased by 19.48%-88.96% and 22.54%107.30%, SOD and CAT activities increased by 4.42%-26.60% and 23.31%-64.68% and Pn and Tr decreased by 40.00%-71.67% and 20.00%-80.00%. In the face of stress, rye seedlings can reduce the damage caused by stress by increasing osmotic substance and antioxidant enzyme activity, so as to adapt to the environment. The results revealed that combined NaCl, AES and freeze-thaw stress had a significant superposing effect on plants compared with single NaCl, AES and freeze-thaw stress. Net photosynthetic rate (Pn) and transpiration rate (Tr)as photosynthetic indices, are easily affected by the environment, and the photosynthetic physiological characteristics of plants will decrease significantly under external stress.