Soybean, an important cash crop, is often affected by soil salinity, which is one of the important types of abiotic stress that affects its growth. Poly (acrylic) acid coated Mn₃O₄ (PMO) has been reported to play a vital role in defending against a variety of abiotic stresses in plants. To date, the effects of PMOs on soybean have not been reported; this study explored the mechanism of PMO-enhanced soybean germination under salt stress. In this experiment, 100 mg/L PMO was used as an immersion agent with a salt treatment of 150 mM NaCl. The results showed that when compared with the PMO treatment, salt stress significantly decreased the germination rate, fresh weight, carbohydrate content, and antioxidant enzyme activity of soybean and significantly increased the contents of reactive oxygen species, malondialdehyde, and osmoregulatory substances. However, PMO treatment enhanced the antioxidant defense system and significantly reduced the malondialdehyde content of soybean. Moreover, the activities of H⁺-ATPase and Ca²⁺-ATPase were significantly higher in treated soybean than in the control, and the content of ATP was also higher in treated soybean than in the control. Generally, PMO regulates the homeostasis of reactive oxygen species and reduces ATP consumption, thereby improving the ability of soybeans to germinate under salt stress. This study provides new insights into how nanomaterials improve plant salt tolerance.

Southern Xinjiang is an important soybean production region in China. However, the short growing season and the cultivation of winter crops (such as wheat) in the region limit the expansion of soybean planting areas. An increased planting density can compensate for the loss in yield due to delayed sowing. To identify the quantitative relationship between increased density and delayed days, a two-year field experiment was conducted at the Tarim University Agronomy Experiment Station. Two sowing dates (April 7 (S1) and May 7 (S2)) and three planting densities of 206,800 plants·ha⁻¹ (D1), 308,600 plants·ha⁻¹ (D2), and 510,200 plants·ha⁻¹ (D3) were used to compare various plant growth parameters and canopy characteristics. Late sowing and a high planting density significantly increased the plant height (S2 was 37.3% higher than S1, and D3 was 17.6% and 8.8% higher than D1 and D2), main stem internode, petiole length, and the mean tilt angle of the leaves (S2 was 22.5% higher than S1, and D3 was 11.7% higher than D2) but reduced the stem diameter (D3 was 28.6% and 12.5% lower than D1 and D2), branch number (S2 was 26.7% lower than S1, and D2 was 75% lower than D1), canopy light transmittance (S2 was 49.2% lower than S1, and D3 was 36.7% and 20.8% lower than D1 and D2), photosynthetic rate, and dry matter. The highest yield was achieved at S1D1, but the lowest yield was found for S2D1. Overall, the results suggest that earlier sowing and a lower planting density contribute to achieving an optimum canopy structure and higher yield. Our conclusions provide a reference for soybean production in southern Xinjiang.

High-temperature stress severely limits soybean growth and yield, particularly in regions with extreme climates such as southern Xinjiang. This study aimed to investigate the regulatory mechanisms by which foliar application of licorice- and goji berry-derived mesoporous self-assembled nanomaterials (LW-CNs) modulates the heat tolerance of soybean seedlings. Soybean seedlings were treated via foliar spraying, and their physiological and biochemical responses were analyzed 3 days after heat stress treatment. The results indicated that LW-CNs treatment significantly improved the plant morphology of soybeans, increasing fresh weight, dry weight, leaf area, and SPAD values, while simultaneously enhancing net photosynthetic rate, transpiration rate, and stomatal conductance. Regarding the antioxidant system, foliar application of LW-CNs significantly increased antioxidant enzyme activities (superoxide dismutase, SOD: 619.5 ± 12.6 U g ⁻¹ vs. 531.2 ± 2.0 U g ⁻¹ ; peroxidase (POD): 110.2 ± 0.5 U g ⁻¹ vs. 71.8 ± 3.7 U g ⁻¹ ). Furthermore, LW-CNs activated the ascorbic acid-glutathione (AsA-GSH) cycle, significantly increasing APX and GR activities as well as GSH and AsA contents, thereby effectively maintaining reactive oxygen species (ROS) homeostasis. Regarding nitrogen metabolism, LW-CNs increased NH ₄ ⁺ content and the activities of key enzymes such as GS, GOGAT, GDH, GPT, and GOT, thereby promoting nitrogen uptake and assimilation. In summary, our findings indicate that foliar application of LW-CNs during the seedling stage is an effective strategy for enhancing soybean heat tolerance and contributes to a deeper understanding of how nanobiotechnology regulates ROS.