The contradiction between increased irrigation demand and water scarcity in arid regions has become more acute for crops as a result of global climate change. This highlights the urgent need to improve crop water use efficiency. In this study, four irrigation volumes were established for drip-irrigated maize under plastic mulch: 2145 m³ ha⁻¹ (W1), 2685 m³ ha⁻¹ (W2), 3360 m³ ha⁻¹ (W3), and 4200 m³ ha⁻¹ (W4). The effects of these volumes on soil moisture, maize growth, water consumption, crop coefficients, and yield were analyzed. The results showed that increasing the irrigation volume led to a 2.86% to 8.71% increase in soil moisture content, a 24.56% to 47.41% increase in water consumption, and a 3.43% to 35% increase in the crop coefficient. Maize plant height increased by 16.34% to 42.38%, ear height by 16.85% to 51.01%, ear length by 2.43% to 28.13%, and yield by 16.96% to 39.24%. Additionally, soil temperature was reduced by 1.67% to 5.67%, and the maize bald tip length decreased by 6.62% to 48%. The irrigation water use efficiency improved by 6.57% to 28.89%. A comprehensive evaluation using the TOPSIS method demonstrated that 3360 m³ ha⁻¹ of irrigation water was an effective irrigation strategy for increasing maize yield under drip irrigation with plastic mulch in the southern border area. Compared to 4200 m³ ha⁻¹, this strategy saved 840 m³ ha⁻¹ of irrigation water, increased the irrigation water use efficiency by 23.96%, and resulted in only a 0.84% decrease in yield. The findings of this study provide a theoretical foundation for optimizing production benefits in the context of limited water resources.

Lycium barbarum has been widely planted in arid and semi-arid areas due to its drought-resistant ability, which is of great economic value as a medicinal and edible homology plant. In this study, the metabolome of the L. barbarum variety “Ningqi 7” under different drought stress conditions was compared and analyzed by the non-targeted UPLC-MS (ultra-high performance liquid chromatography with mass spectrometry) technique. The results showed that drought stress significantly decreased the water content of leaves, increased the activity of antioxidant enzymes in plants, and up-regulated the metabolites and pathways involved in osmoregulation, antioxidant stress, energy metabolism, and signal transduction. Under moderate drought (40–45% FC), L. barbarum accumulated osmoregulatory substances mainly through the up-regulation of the arginine metabolism pathway. At the same time, phenylalanine metabolism and cutin, suberine, and wax biosynthesis were enhanced to improve the antioxidant capacity and reduce water loss. However, in severe drought (10–15% FC), L. barbarum shifted to up-regulate purine metabolism and lysine degradation and redistributed energy and nitrogen resources. In addition, vitamin B6 metabolism was significantly upregulated in both groups of stress levels, playing a key role in antioxidant and growth regulation. These observations delineate the metabolic adaptations of L. barbarum “Ningqi 7” in response to drought stress.

In nature, the symbiotic relationship between plants and microorganisms is crucial for ecosystem balance and plant growth. This study investigates the impact of Epichloë endophytic fungi, which are exclusively present aboveground, on the rhizosphere microbial functions of the host Melica transsilvanica. Using metagenomic methods, we analyzed the differences in microbial functional groups and functional genes in the rhizosphere soil between symbiotic (EI) and non-symbiotic (EF) plants. The results reveal that the presence of Epichloë altered the community structure of carbon and nitrogen cycling-related microbial populations in the host’s rhizosphere, significantly increasing the abundance of the genes (porA, porG, IDH1) involved in the rTCA cycle of the carbon fixation pathway, as well as the abundance of nxrAB genes related to nitrification in the nitrogen-cycling pathway. Furthermore, the presence of Epichloë reduces the enrichment of virulence factors in the host rhizosphere microbiome, while significantly increasing the accumulation of resistance genes against heavy metals such as Zn, Sb, and Pb. This study provides new insights into the interactions among endophytic fungi, host plants, and rhizosphere microorganisms, and offers potential applications for utilizing endophytic fungi resources to improve plant growth and soil health.

Epichloë endophytic fungi are important microbial resources in agriculture and animal husbandry. Because of their stable symbiosis, species transmission, and positive effects on host plants, the use of endophytic fungi in grass breeding is of great significance. In this study, six inoculation methods were used, including the sterile seedling slit inoculation method, sterile seedling cut inoculation method, sterile seedling injection inoculation method, seed soaking inoculation method, seed piercing and then soaking inoculation method, and seed slit inoculation method. Spectrometry was used to construct new symbionts, and Liquid Chromatography–mass spectrometry was used to analyze the effects of endophytic fungi on the metabolism of new hosts. The physiological response of the new symbionts to salt and alkali stress was studied using a pot experiment. The results were as follows: In this study, Epichloë bromicola was successfully inoculated into Bromus inermis via the sterile seedling slit inoculation method, and new symbionts (EI) were obtained; the vaccination rate was 2.1%. Metabolites up-regulated by EI are significantly enriched in citrate cycle and ascorbate and aldarate metabolism, suggesting that the symbiosis of endophytic fungi indirectly triggers the production of reactive oxygen species (ROS) through multiple metabolic pathways. The saline–alkali stress test showed that the host antioxidant system was active after inoculation, and the total antioxidant capacity was significantly increased compared with non-symbionts (EF) under mild stress (p < 0.05), which provided important clues to reveal the complex mechanism of plant–fungus symbiosis. This study provides practical guidance and a theoretical basis for plant adaptation under climate change, health management of grass seeds, and soil improvement through endophytic fungi.