Soil salinization is a growing concern that degrades soil quality and inhibits agricultural productivity. Miscanthus species have received wide attention because of their high calorific potential, their value as an energy plant, and their ability to maintain high biomass accumulation. However, most studies focused on the biochemical and physiological responses to salt stress while neglecting the osmotic adjustment processes and the contribution of both organic and inorganic substances to these processes. This study evaluates the response mechanism of Miscanthus sinensis to salt stress (0-300 mM of NaCl) by evaluating the growth and photosynthetic parameters, photosynthetic response to light, and contribution of organic and inorganic substances to osmotic potential. The results revealed that M. sinensis adopted Na + compartmentalization and reallocation of biomass to the aboveground parts to mitigate the negative impact of salinity stress. Specifically, Na+ accumulated more in the root and leaf, with an increment magnitude of 75.4-173.9 and 56.7-217.1 times, respectively. This was supported by the changing trend of the stem/leaf ratio (25.1 %-55.9 %) compared to the root/shoot ratio (12.3 %-18.3 %). Also, salt-induced stress decreased the leaf's water content and water use efficiency as a result of low intracellular osmosis, and to mitigate osmotic damage, M. sinensis enhanced the accumulation of proline. These results offer theoretical and scientific insights into managing the cultivation and improving the yield of M. sinensis and other energy herbaceous plants in saline soils.

Analyzing the ecological and behavioral effects of changes in irrigation practices in oases provides valuable insights for water resource management and the sustainable development of oasis agriculture in arid regions. Taking the Yanqi Basin as a case study, this research draws on long-term empirical data and remote sensing information to evaluate the ecological and irrigation behavior effects resulting from shifts in irrigation methods. And explores the deep societal causes behind these behavioral changes. The findings demonstrate: (1). Between 2000 and 2010, the rapid adoption of groundwater extraction and mulched drip irrigation (MDI) technology temporarily alleviated the water supply-demand contradiction. However, from 2010 to 2020, as the adoption of water-saving practices significantly expanded and agricultural irrigation areas grew substantially, the irrigation paradox emerged, where increased efficiency paradoxically led to greater water consumption. (2). From 2000 to 2020, the groundwater table depth in the irrigation district dropped by 8-16 m, total soluble salt content decreased by 2-5 g/L, and soil salinity decreased by 4-12 g/kg. The proportion of severely salinized and saline soil areas fell from 21.74% in 1999 to 9.75% in 2020. The longstanding salinization issues that had plagued the irrigation district were effectively mitigated with the widespread adoption of MDI. (3). The irrigation district's vegetation ecological quality index (VEQI) showed a slow but steady upward trend in cultivated areas over the years. In contrast, natural vegetation areas such as forests and grasslands exhibited an initial increase followed by a decline. The trends in VEQI responded well to changes in irrigation practices. (4). The economic benefits driven by water-saving technologies and the expansion of cultivated land are deep societal factors behind the changes in irrigation behavior. These benefits also fostered improvements in users' understanding and awareness of irrigation practices. The shift in irrigation methods in the Yanqi Basin has led to a decline in groundwater levels, an irrigation paradox, and moderate damage to natural vegetation. However, it has had a significant positive impact on improving regional groundwater quality and mitigating soil salinization. Furthermore, it facilitates the further exploration of regional water conservation potential, enhancing the research on the regional water and soil resource management system.

The use of plant growth promoting rhizobacteria (PGPRs) to improve crop growth under salt stress is gaining attention in recent years. In this study, we evaluated the potential of Bacillus amyloliquefaciens strain Q1 to mitigate salt stress in barley. Barley seedlings were inoculated without (-) or with (+) Q1 and then subjected to four salt levels (0-320 mM) to assess the changes in plant growth, photosynthetic attributes, ion homeostasis, and antioxidant capacity. Our results revealed that the slight salt stress (80 mM) caused little damage to plant growth and physiological processes of barley seedlings, indicating the potential of barley for crop production in saline soils equal to or less than this salt level. However, the moderate (160 mM)- or severe (320 mM)-level salt stress considerably reduced the plant growth of barley seedlings, because of the inhibition of photosynthetic capacity and disruption of Na+/K+ homeostasis. The inoculation with Q1 notably ameliorated these detrimental effects of salt stress, and its efficacy was more predominant at the severe salt level. Moreover, Q1 significantly enhanced the activities of antioxidant enzymes in barley at the severe salt level, but not at the slight or moderate salt level. Taken together, it is concluded that Q1 has limited promoting effect on barley under the normal growth condition, whereas it is capable to help barley maintain much better growth and performance under salt stress, especially at the severe level. Our study has expanded the list of PGPR resources for sustainable utilization of saline land.

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.

The traditional view of Na+ as harmful and Ca2+ as beneficial doesn't always apply in multi-cationic soil solutions. Initially, adding Ca2+ promotes Na+ leaching, reducing salinity, but excess Ca2+ becomes counterproductive. As Na+ leaches, the soil's Ca2+-Na+-Mg2+ mix shifts to Ca2+-K2+-Mg2+, Ca2+'s function changes, even causing the opposite effect. To investigate the complex mechanism of Ca2+ to Na+-Mg2+ and K+-Mg2+, we conducted an indoor soil column experiment using saline water (4 dS m(-1)) with different cation compositions [Na+-Ca2+-Mg2+ (NCM), Na+-Mg2+ (NM), K+-Ca2+-Mg2+ (KCM), K+-Mg2+ (KM)] and deionized water as the control (CK). The results showed that NM exhibited the highest crack volume, while KM had the greatest macropore volume, with NM having approximately 15 % more crack volume than KM. Notably, only NM displayed a more pronounced inclination towards pore anisotropy value of 0 when compared to CK. NCM and KCM had higher pore anisotropy values than NM and KM. KM and KCM had more cracks angled ranging from 45-90 degrees than NM and NCM. KCM notably decreased transitional macropores 0.05) observed in widths < 2.5 mm between KCM and KM. NM displayed the shallowest macropore distribution and the highest variability in macropore length among all treatments. Only NCM showed significantly reduced variability in both macropore length and width compared to CK. In summary, Ca2+ exhibited distinct action patterns on K+-Mg2+ and Na+-Mg2+. For specific soil types and cationic compositions, Ca2+ may not fully exert its amendment effects. However, Ca2+'s effect is soil-specific, necessitating comprehensive studies across varied soil types.

In cold and arid saline areas, the mechanical properties of soils are usually significantly affected by some complicated conditions, especially the coupled effects of the freeze-thaw-dry-wet (F-T-D-W) cycles and soil salinization. This study experimentally investigated the effect of F-T-D-W cycles on the shear performances and microstructures of silty clay that was salinized during wetting processes. Three types of soil samples with different dry densities were designed: (1) silty clay samples without salt (Category I); (2) silty clay samples with salt (Category II); and (3) silty clay samples that were salinized during wetting processes (Category III). Direct shear and scanning electron microscopy (SEM) tests were carried out, the variations in the shear strength, surface deterioration, and shear parameters (e.g., cohesion and internal friction angle) were analyzed, and the degradation mechanism was revealed. The results show that the F-T-D-W cycles and soil salinization significantly affect the shear strength of soils, especially for the samples with low dry densities. The shear strengths of soil samples with and without salt (Categories I and II) decrease as the F-T-D-W cycles increase. Besides, the cohesion of soil samples increases with dry density and declines with the F-T-D-W cycles due to the appearance of cracks and bond failure among soil particles. In addition, there is a threshold number of F-T-D-W cycles to significantly reduce the cohesion of soil samples, and the threshold numbers for soil samples Categories I and II are six and three, respectively. The repeated expansion and shrinking of soils accelerate the damage to the soil structure, which results in a decrease in cohesion and interparticle force. However, when the concentration of salt solution in soils exceeds the saturation concentration, a new denser soil skeleton is formed by the soil particles and surrounding salt crystals, which improves the shear strength of the soil samples. This study could provide deep insights into the shear performance and microstructures of silty clay exposed to F-T-D-W cycles. (c) 2024 American Society of Civil Engineers.

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.