Peanut productivity is severely restricted by soil salinization and associated nutrient deficiency in saline soil. The quinoa–peanut relay intercrop pattern (IP) is a promising planting system that utilizes the biological advantages of quinoa to improve soil ecological functions and productivity. However, the effects of IP on soil physicochemical and biological properties and the yield formation of the combined peanut crop are still unclear. Two-year field experiments in coastal saline soil were conducted to explore the effects of IP on peanut growth and pod yield, soil physicochemical properties, and microbial community characterization at different growth stages of peanut based on the traditional monocrop pattern (MP). The results show that IP promoted peanut pod yield, although there was the disadvantage of plant growth at an early stage. Soil water content, electrical conductivity (EC), and Na⁺ content in the peanut rhizosphere were lower, whereas K⁺, NH₄⁺, and total organic carbon (TOC) contents were higher in IP systems at both the vegetative and reproductive stages. The pod yield of peanut was significantly negatively correlated with soil EC and Na⁺ contents at the vegetative stage, but positively correlated with K⁺, NO₃⁻, NH₄⁺, PO₄³⁻, and TOC contents at the reproductive stage. IP rebuilt the composition of the soil bacterial community in the peanut rhizosphere and increased the abundance of the beneficial bacterial community, which were positively correlated with soil TOC, K⁺, NH₄⁺, NO₃⁻, and PO₄³⁻ contents. These findings suggest that IP can increase peanut pod yield through optimizing soil physicochemical properties and microbial community composition, and it is a promising planting system for improving agricultural production in coastal saline lands.

Soil salinization has become a major environmental factor severely threatening global food security. The application of porous minerals could significantly ameliorate soil fertility and promote plant productivity under salt stress conditions. However, the effects of porous minerals on improving the salt resistance of grain crops in coastal saline soils is not fully studied. In this work, the shoot growth and grain yield of wheat plants grown in coastal saline fields, respectively amended with the four naturally available porous minerals, diatomite, montmorillonite, bentonite and zeolite, were assessed. The application of porous minerals, especially zeolite, significantly improved the biomass and grain yield of wheat plants under saline conditions, as demonstrated by the augmented plant fresh mass (14.8~61.2%) and increased seed size (3.8~58.8%) and number (1.4~57.5%). Soil property analyses exhibited that porous-mineral amendment decreased soil sodium content and sodium absorption ratio, and increased soil nutrients in both the rhizosphere and nonrhizosphere of wheat plants. Further quantitative-PCR and 16S high-throughput sequencing analysis revealed that porous-mineral application also remarkably increased the abundance of bacterial 16S rRNA (0.8~102.4%) and fungal 18S rRNA (89.2~209.6%), and altered the composition of the soil microbial community in the rhizosphere of wheat. Our findings suggest that zeolite could be used as an ideal salt soil amendment, and the changes in soil properties and microorganisms caused by the application of porous minerals like zeolite improved the salt resistance of wheat plants in coastal saline land, leading to increased shoot growth and seed production.

Quinoa (Chenopodium quinoa Willd.) has been widely grown as a cash crop. However, the molecular mechanism by which it responds to cold stress at the seed germination stage is still largely unknown. In this study, we performed a comparative transcriptomic analysis between the cold-tolerant cultivar XCq and cold-sensitive cultivar QCq in response to cold stress. A total number of 4552 and 4845 differentially expressed genes (DEGs) were identified in XCq and QCq upon the treatment of cold stress, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that the mitogen-activated protein kinase (MAPK) signaling pathway was identified only among the up-regulated DEGs in XCq.The expression of DEGs, which encoding transcription factors, such as AP2/ERF, bHLH, bZIP, MYB, ICEs, and CORs related to cold response, were higher in XCq than in QCq in response to cold stress. Weighted gene co-expression network analysis (WGCNA) showed that DEGs clustered in the co-expression modules positively correlated with the factors of quinoa variety and temperature were significantly enriched in the oxidative phosphorylation metabolic pathway. Further physiochemical analyses showed that the activities of superoxide dismutase and peroxidase as well as the contents of soluble protein and sugar, were significantly higher in XCq than in QCq. In summary, MAPK signaling and oxidative metabolism were the key pathways in quinoa upon cold stress. Our findings revealed that the enhanced activities of antioxidant enzymes alleviate the lipid peroxidation of membranes and promote the accumulation of osmotic adjustment substances, thereby enabling seeds to better resist oxidative damage under cold stress.

Halophytes are thought to recruit nitrogen (N)-cycling microorganisms that alleviate nutrient limitation in coastal saline soils, yet the relative importance of geographic environment versus halophyte identity in structuring these communities remains unclear. We sampled rhizosphere soils of eight plant species (18 species × site combinations) at four coastal sites in the Yellow River Delta and Laizhou Bay, China. Two sites had low salinity (0.56–0.71‰) and two had high salinity (8.48–11.40‰). The abundances of ammonia-oxidizing archaea (AOA, arch-amoA gene) and bacteria (AOB, amoA gene) and denitrifiers (nirS, nirK, nosZ) were quantified via qPCR. AOA, AOB, and nosZ-type denitrifier communities were profiled using amplicon sequencing. The geographic location significantly structured all three communities (PERMANOVA R² = 0.65–0.68, p < 0.01), whereas plant traits did not; salinity, moisture, pH, and total carbon were the main correlates. High-salinity sites harbored ~14-fold more nirS copies and higher AOA diversity than low-salinity sites, with dominance shifting from Nitrososphaera to Nitrosopumilus in AOA and from Nitrosovibrio to Nitrosospira in AOB. Plant-associated effects were weaker and limited to gene abundance and α-diversity. Secretohalophytes harbored the highest AOA abundance, and perennials had ~10-fold more nosZ copies than annuals. Our results contribute to improving knowledge on different effects of geographic environment and host plant traits on the N-cycling microbial assembly in coastal saline soils.

The substrate-induced respiration-inhibition (SIRIN) method has been used to estimate fungi-derived N₂O emissions, but its contribution to soil N₂O emissions remains unclear. There is a need to quantify the fungal fraction of N₂O production more precisely. Here, using isotopocule analysis, we assessed the relative contribution of fungi to soil N₂O production potential under denitrifying conditions, where key limiting factors of denitrification (soil moisture, soil NO₃⁻, and electron donor) were removed. The result showed that the ratio of fungi-derived N₂O emissions (R_F) was 0.83~4.28% in paddy soils, 13.80~23.21% in vineyard soils, and 15.34~65.94% in vegetable field soils, respectively. This indicated that the bacteria were the dominator of soil N₂O production potential in most cases, but fungal pathways could be significant in vegetable field soils. The experiment with bactericide addition showed that inhibitors could affect non-target microorganisms in the SIRIN method. Our further analyses suggest that it is worth to explore the effect of soil organic carbon and microbial synergies on fungi-derived N₂O emissions.