How nitrogen (N) levels affect agronomic performance and the nutrient utilization process in wheat grown in rainfed coastal saline soils remains largely unknown. This study investigated the influence of three N supply treatments (0, 100, and 200 kg/ha) on the growth and accumulation of P, Ca, Mg, K, Na, Zn, Fe, and Se of eight wheat genotypes across two consecutive seasons (2020–2021, 2021–2022) in a rainfed coastal field. Both agronomic performance and nutrient accumulation were significantly affected by N supply and genotypic effects. The increased total accumulation of nutrients was mainly due to enhanced agronomic performance by N supply. Grain Zn and Fe concentrations increased, while the grain Se concentration decreased with the N supply increasing. Genotype “Jimai 775” exhibited both a higher grain yield and a higher nitrogen agronomic efficiency among the tested genotypes. The association among agronomic traits and nutrient accumulation was obviously modified by the N supply, as revealed by principal component analysis, correlation analysis, and stepwise multiple regression models. These findings suggest that both the N supply level and genotypic differences should be taken into consideration to enhance nutrient utilization in wheat cultivated in coastal saline soils.

The soil carbon pool in saline–alkali land is a research hotspot in the field of agricultural environmental science. However, there are no systematic conclusions regarding the paddy soil carbon pool in the Yellow River Delta in China. Therefore, this study focused on the paddy soil in the Yellow River Delta; using statistical analysis methods and establishing relevant models, we explored the dynamic changes in organic carbon and its active components and their influencing factors in saline paddy fields under two planting patterns. The results showed that there was no significant difference in the dissolved organic carbon (DOC) content between the two planting patterns. However, the rice–wheat rotation pattern was more conducive to the accumulation of microbial biomass carbon (MBC). The soil organic carbon (SOC) and readily oxidizable organic carbon (ROC) contents increased under the two patterns and different salinization treatments. The results of the redundancy analysis and the random forest model indicated that SSA was the key environmental parameter affecting SOC and its active components under the single-season rice pattern. Under the rice–wheat rotation pattern, soil sucrase activity (SSA) was also a key environmental factor for predicting the SOC content, while electrical conductivity (EC) contributed the most to the active components of SOC. The PLS-PM model showed that the soil carbon sequestration capacity could be improved by enhancing soil enzyme activity under the rice–wheat rotation pattern, while the influence of the soil environment on SOC and its active components was not obvious under the single-season rice pattern. In general, the rice–wheat rotation pattern has agricultural advantages in terms of maintaining ecological balance and can be widely promoted in this region. The results of this study have important practical significance for promoting the green and low-carbon development of agriculture in the Yellow River Delta region and also lay a foundation for subsequent long-term positioning observations and studies on multi-factor interactions.

How nitrogen (N) levels affect agronomic performance and nutrient utlization process in wheat grown in rainfed coastal saline soils remains largely unknown. This study investigated the influence of three N supply treatments (0, 100, and 200 kg/ha) on the growth and accumulation of P, Ca, Mg, K, Na, Zn, Fe, and Se of eight wheat genotypes across two consecutive seasons (2020-2021, 2021-2022) in a rainfed coastal field. Both agronomic performance and nutrient accumulation were significantly affected by N supply and genotypic effect. The increased total accumulation of nutrients were mainly due to enhanced agronomic performance by N supply. Grain Zn and Fe concentrations increased while grain Se concentration decreased with N supply increasing. Genotype “Jimai 775” exhibited both a higher grain yield and a higher nitrogen agronomic efficiency among tested genotypes. The association among agronomic traits and nutrients accumulation was obviously modified by N supply as revealed by principal component analysis, correlation analysis, and stepwise multiple regression models. These findings suggest both N supply level and genotypic difference should be taken into consideration to enhance nutrient utilization in wheat cultivated in coastal saline soils.

Soil salinization is one of the most important factors limiting the sustainable development of global agriculture. As the core driving force of the soil carbon cycle, soil-carbon-metabolism-related enzyme activity is very important for soil ecological balance and fertility enhancement. To explore the spatial and temporal variation characteristics and coupling mechanisms of soil water, salt, nutrients and enzyme activities in different salinized wheat fields in the Yellow River Delta, field experiments were conducted in Dongying City, Shandong Province. The results showed that the soil moisture content of the low-salt wheat field was higher and that the salt content of three wheat fields was concentrated in the 0–20 cm and 80–100 cm soil layers. Here, soil nutrients and enzyme activities are concentrated in the 0–20 cm topsoil, with significant differences in different degrees among salinized wheat fields at the different growth stages of wheat. Overall, invertase activity (S-SC) and amylase activity (S-AL) presented a trend of low salt > high salt > medium salt, while cellulase activity (S-CL) presented a trend of medium salt > low salt > high salt. Redundancy analysis showed that available potassium (AK) (67.6%) and electric conductivity (EC) (21.2%) in the low-salinity wheat field, total nitrogen (TN) (48.6%) and AK (28.8%) in the medium-salinity wheat field, and EC (67%) and soil organic matter (SOM) (19%) in the high-salinity wheat field contributed the most to soil enzyme activity. This study provides a theoretical basis for the management and sustainable development of different salinized wheat fields in the Yellow River Delta.

Magnesium (Mg) release (MGR) proteins play a crucial role in maintaining Mg²⁺ homeostasis in plant cells. However, MGR family genes have not yet been explored in crops. This study identified the wheat MGR (TaMGR) family members via BlastP alignment. A total of 15 MGR genes were mapped to 12 chromosomes. Cis-element prediction in the promoter region revealed that the ABA-responsive element (ABRE) was 100% conserved among all family members. Collinearity analysis indicates that MGR genes in monocot plants may have higher conservation compared to dicot plants. Expression profiling analyses uncovered the expression patterns of TaMGR genes across diverse tissues and under various stresses. Our results demonstrated that TaMGR5D and TaMGR5A.2 were significantly induced by both powdery mildew and stripe rust pathogen infections, whereas TaMGR4A transcript levels were upregulated in response to drought, heat and their combined stress. These findings indicate that TaMGRs may contribute coordinately to the regulation of wheat growth and development as well as adaptive responses to adverse conditions through member-specific expression patterns. This study systematically identified and analyzed the evolution and expression regulation characteristics of TaMGRs, providing a theoretical basis for in-depth research on the functional mechanisms of the TaMGRs and for improving the Mg use efficiency and stress adaptability of wheat via molecular approaches.

Low energy N⁺ ion beam implantation has been used to create the novel rice mutant “shuangli”, which produces partially fertile spikelets containing double grains. Abnormal ovule development is a major cause of partial fertility and grain diversity in rice mutants. To elucidate the developmental mechanism of ovule diversity in shuangli, ovules undergoing development were stained using eosin Y and H33342 and observed using confocal laser scanning microscopy. Different developmental abnormalities were observed in the ovary, embryo sac, and ovule. Abnormal development was observed in 35.18% of the ovary structures, primarily manifesting as “tumor” like cell clusters, “false ovaries”, stamen degeneration, and double ovaries. In the embryo sac, abnormal development occurred in about 17.35% of the megaspore cells, including the formation of three nuclei, two daughter cells of asynchronously divided dyads, multiple megaspore tetrads, and “narrow and elongated” cavities. At the female gametogenesis stage, the abnormal development rate was 27.53%, mainly involving the degeneration of the central polar nucleus, egg apparatus, antipodal cell mass, or female germ unit. In shuangli, abnormal development occurred in 28.06% of the ovule structures, including lateral tissue, nucellar tissue, double ovules and double embryo sacs. Of the observed lateral tissues, 8.27% did not differentiate into sexual reproductive tissue, which affected the fertilization of the embryo sac, leading to atrophy and degeneration. A new abnormal tissue similar to the inner integument was found on both sides of the nucellar tissue, and the two specialized nucellar tissues appeared to have “staggered” growth within a single ovary. Of the examined ovules, 10.79% exhibited different types of double ovules, including heart-shaped, “anatropous”, “conjoined” structures. However, the double ovules typically developed synchronously, explaining the production of different sizes of the two grains in shuangli. In addition, “double” embryo sacs from two “twinborn” nucelli were found in one ovule, and the frequency of “double” embryo sacs was 3.60%. Therefore, ovule development diversity may result in fertilization or gradual degeneration after fertilization, explaining the lower fertility of shuangli at the embryological level.