Changyan Tian

Viruses are important components of soil biodiversity and ecosystem functions. However, their response to soil salinity stress, including ecological patterns and functional potential, remains poorly understood. Here, metagenomic data from 84 saline soil samples were retrieved from public databases and analysed. Viral sequences were extracted from metagenomes, and auxiliary metabolic genes (AMGs) were identified. 83.34% of the vOTUs had no detectable gene‐sharing links with the RefSeq Viral database, highlighting the unexplored diversity of saline soil viromes. In soils with higher salinity, viral genomes exhibited larger genome sizes and increased GC content. The diversity of temperate viruses (3.16–7.32) was significantly higher than that of lytic viruses (2.49–6.99). Although the diversity of temperate viruses decreased with increasing salinity, no significant trend was observed for lytic viruses. Viral abundance correlated positively with host abundance, consistent with the ‘piggyback‐the‐winner’ ecological coupling hypothesis. Functional potentials varied with salinity, and structural analysis showed changes in atomic interactions in key proteins ( NhaA , ACAT ) across salinity gradients. Significantly positive correlations were found between viral diversity and functional potential related to salt tolerance, carbon fixation, organic phosphorus mineralisation and nitrogen metabolism. These results suggest viral traits correlate with salinity gradients and provide insights into viral responses in saline soils.

Introduction: Halophyte-based intercropping utilizes the salt-absorbing capacity of halophytes to create a low-salinity environment for glycophytes, but it also intensifies competition for water and readily mobile nutrients. Optimizing the proportion of halophytes may therefore balance salt alleviation and resource competition. Methods: Using a soybean (S)/ Suaeda salsa (H) system, this study investigated plant growth dynamics and spatiotemporal changes in soil water and salt content under monoculture and two intercropping configurations (S1H1, 1:1; S2H1, 2:1) in moderately saline soils. Results: S2H1 had a clear land-use advantage, with land equivalent ratio (LER) values of 1.66-1.85, whereas S1H1 showed little or no advantage (LER = 0.98-1.13). Although soybean grain yield in S2H1 did not differ significantly from soybean monoculture, it maintained plant density and produced the highest number of effective pods per plant. Reducing the planting density of S. salsa also significantly increased its biomass and Na uptake per drip line. Although aboveground biomass and Na removal per unit land area were lower than in S. salsa monoculture, S2H1 achieved higher soil desalination rates, indicating more favorable spatial redistribution of soil salinity. These advantages were associated with salt accumulation around S. salsa roots, reduced light competition, improved soybean water acquisition through root proliferation into wetter soil zones, and increased soil available phosphorus. Discussion: In moderately saline soils-where salinity inhibits glycophytes yet is inadequate for dense halophyte stands-appropriately reducing the planting proportion of S. salsa can improve land-use efficiency and achieve the dual objectives of maintaining soybean production and soil desalination.

Introduction: Halophyte-based intercropping may involve root interactions beyond desalinization in alleviating salt stress in glycophytes. Methods: To elucidate the mechanisms of root interactions enhancing soybean ( Glycine max ) salt tolerance intercropping with Suaeda salsa , we analyzed rhizosphere metabolomes and bacterial communities under two salt treatments (no additional NaCl, S1; 3 g kg ^–1 NaCl, S3) and three root interaction modes: (1) plastic barrier (no root interactions), (2) nylon mesh barrier (root interactions only), and (3) no barrier (root interactions with potential salt redistribution). Results: Both NL and NS significantly increased soybean biomass compared with PL under both salt treatments, with no significant difference between NL and NS. Under S3, NL increased soybean biomass by 80% relative to PL without significantly changing soil electrical conductivity, accompanied by increases in rhizosphere carbohydrates, organic acids, betaine, flavonoids, and putative plant growth-promoting bacteria (PGPB). Although soybean rhizosphere Na ⁺ decreased under NS compared with PL and NL, this was accompanied by reduced putative PGPB abundance and no further biomass increase compared with NL. Coumestrol, trehalose-6-phosphate, and isopentenyl pyrophosphate (IPP) were identified as hub metabolites associated with soybean rhizosphere microbial community structure, with the IPP-related module representing a potential component of the salt-response network. Intercropping also increased available phosphorus (AP) in both species’ rhizospheres, with increases in soybean associated with organic acids and those in S. salsa associated with rhizosphere pH shifts and putative PGPB changes. Discussion: These findings indicate that root interactions enrich salt−tolerance−related metabolites in the soybean rhizosphere and suggest potential metabolic-microbial coupling underlying intercropping−induced salt tolerance.

Soil salinization threatens agricultural sustainability and food security, especially in arid and semi-arid regions, yet how salinity gradients reshape multi-trophic networks and their associations with functional genes remain unclear. We investigated soil bacteria, fungi, protists, nematodes, and the carbon-fixation gene cbbL along a natural salinity gradient (electrical conductivity: 1.2–12.4 mS cm⁻¹) in Karamay, Xinjiang. Salinity acted as a key environmental filter, significantly differentiating biotic communities into low- and high-salinity groups. Compared with bacteria and fungi, protists and nematodes exhibit higher sensitivity to salinity shifts from non-saline to slightly saline soils, with their Shannon diversity decreasing by 74.2% and 50.4%, respectively (p < 0.05). High salinity significantly reduced the connectivity, modularity, and robustness of soil multi-trophic co-occurrence networks, resulting in 36.8% fewer edges, 24.2% lower modularity, and diminished network robustness compared to low-salinity conditions. Crucially, salinity was associated with functional decoupling, defined as a shift in the dominant drivers of microbial carbon sequestration potential. At low salinity, biotic factors explained 94.2% of cbbL variation, whereas at high salinity abiotic factors governed 86.1%, as shown by GBM (Gradient Boosting Machine) analyses. Our findings indicate that protists and nematodes can act as early warning indicators for soil salinization, and biotic network complexity represents a core metric for assessing saline soil ecosystem stability. This study reveals salinization-induced biota–function decoupling patterns and provides insights for saline soil health assessment and biotic restoration.

Actual evapotranspiration (ET_a) is an important component of the surface water cycle. The geeSEBAL model is increasingly being used to estimate ET_a using high-resolution remote-sensing data (Landsat 4/5/7/8). However, due to surface heterogeneity, there is significant uncertainty. By optimizing the quantile values of the reverse-modelling automatic calibration algorithm (CIMEC) endpoint-component selection algorithm under extreme conditions through 212 global flux sites, we obtained the optimized quantile values of 11 vegetation types of cold- and hot-pixel endpoint components (T_s and NDVI). Based on the observation data of the global FLUXNET tower, the sensitivity of 20 parameters in the improved geeSEBAL model was determined through Sobol’s sensitivity analysis. Among them, the parameters dT and SAVI_,hot were confirmed as the most sensitive parameters of the algorithm. Subsequently, we used the differential evolution Markov chain (DE-MC) method to analyse the uncertainty of the parameters in the geeSEBAL model used the posterior distribution of the parameters to modify the sensitive parameter values or ranges in the improved geeSEBAL model and to simulate the daily ET_a. The results indicate that by analysing the end element components of the geeSEBAL model (T_s and NDVI), quantile numerical optimization and parameter optimization can be performed. Compared with the original algorithm, the improved geeSEBAL model has significantly improved simulation performance, as shown by higher R² values, higher NSE values, smaller bias values, and lower RMSE values. The most suitable values of the predefined parameter Z_oh were determined, and the reanalysis of meteorological data inputs (relative humidity (RH), temperature (T), wind speed (WS), and net radiation (R_n)) was also found to be an important source of uncertainty for the accurate estimation of ET_a. This study indicates that optimizing the quantiles and key parameters of the model end component has certain potential for further improving the accuracy of the geeSEBAL model based on high-resolution remote-sensing data in estimating the ET_a for various vegetation types.

Halophyte-based desalinization is emerging as a promising technology for saline agriculture. However, few studies have integrated halophytes into intercropping systems. This study investigated Suaeda salsa and soybean intercropping and the associated mechanisms, including changes in salt, nutrients, and bacterial communities at three salt treatments (control, 3‰, and 5‰). The results showed that regardless of salt treatment, soybean biomass and P content significantly increased in intercropping compared with monocropping, by an average of 32% and 51%, respectively (p < 0.05), indicating interspecific facilitation. Under 5‰ salt, soybean mortality decreased from 37% in monocropping to 10% in intercropping, and shoot Na decreased by over 60% in intercropping; the rhizosphere Na⁺, Cl⁻, and NO₃⁻–N decreased in intercropping by over 75% compared with monocropping, and the response ratios correlated negatively with S. salsa biomass (p < 0.01). The soybean rhizosphere bacterial community in intercropping was enriched with the genera Sphingomonas, Salinimicrobium, Lysobacter, Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium, and Ramlibacter, and the bacterial co-occurrence network exhibited increases in the number of nodes and edges, average degree, and average clustering coefficient. Considering the combined effects, the soybean biomass of intercropping correlated positively with bacterial co-occurrence network parameters, including average degree and number of edges, independent of tissue salt and nutrient content, and that of monocropping correlated negatively with tissue salt content. These results demonstrate that S. salsa intercropping could alleviate salt stress in soybean by creating a low-salt environment and improving its nutrient accumulation and rhizosphere bacterial community, and emphasize the importance of microbial communities in influencing soybean growth.