Jinbiao Liu

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.

Soil salinization threatening natural and agricultural production challenges global food security. Halophytes are of great interest in soil desalinization in recent years; yet, there is a lack of a comprehensive quantitative overview of biotic and abiotic factors for halophytes’ desalinization performance across global scales. Here, a meta-analysis was conducted using 400 observations from 53 peer-reviewed studies to assess desalinization by halophytes in relation to 27 variables. Results showed that soil salinity was significantly decreased in halophytes field on average by 37.7% compared to control on a global scale (p < 0.05). Desalinization performance was better in cold and hot regions than in temperate regions, in dry regions than in wet regions, in alkaline saline soils than in neutral saline soils, and in conditions with low sand content than high sand content. Under aboveground harvest treatment, desalinization increased with the years of cultivation, while no trends were detected under no harvest treatment, indicating the importance of aboveground accumulation. Desalinization was not related to soil CaCO₃ content but was accompanied by soil structure improvement, nutrition enrichment, and microbe propagation, implying other root-microbe-soil interactions rather than CaCO₃ dissolution play important roles. Shoot biomass could be used as an indicator of the desalinization performance, and the performance would not be decreased due to the high uptake selectivity for K⁺ over Na⁺. Notably, desalinization was similar in the pot experiments and field experiments, but pot experiments would magnify the contribution of aboveground salt accumulation to desalinization. Our findings can help to expand the applicability and efficiency of halophytes for sustainable agricultural development in saline soils.