In Northeast China, increasing agricultural activities has led to severe soil compaction, reducing soil aeration and water infiltration capacity. Conservation tillage, through multiple approaches, alleviates this compaction while simultaneously enhancing crop yields and promoting sustainable agricultural production. In light of domestic and international developments, this paper provides a detailed elaboration on conservation tillage (CT) as a sustainable agricultural practice system. It examines its core technical measures, global adoption status, and impacts on soil physicochemical properties. Furthermore, by analyzing the causes and detrimental effects of soil compaction, it proposes approaches and elucidates the significance of using CT to alleviate compaction in black soils. Integrating considerations of its influence on climate change, economic benefits, future development, challenges, and trends, the paper offers a forward-looking perspective.

Soybean is an important protein source, economic crop, and strategic agricultural product, which is related to nutrition and health, industrial development, and food security. Mepiquat chloride (MC) can influence yield, but its effectiveness depends on application timing and concentration. We hypothesized that optimal MC application enhances photosynthetic efficiency and carbohydrate metabolism, thereby increasing yield. A pot experiment was conducted using two cultivars (HN44, HN65) with four MC concentrations (50–400 mg/L) applied at seedling (V3), flowering (R1), or both stages (V3 + R1). Dry matter, photosynthesis, carbohydrates, and yield were evaluated. MC significantly altered dry matter partitioning; 200 mg/L at seedling stage increased total dry matter in HN65 at R6. MC enhanced net photosynthetic rate and PSII efficiency in a concentration-dependent manner, particularly improving photoprotective capacity in HN65. Leaf carbohydrate accumulation was also affected. Yield gains were stage- and cultivar-specific: seedling-stage 200 mg/L increased grain weight per plant in HN65, while flowering-stage 50 mg/L was most effective for HN44. Combined applications (200–400 mg/L) produced the highest yields for both cultivars. This is the first comparative evidence that HN44 and HN65 exhibit divergent yield responses to MC timing—HN44 benefits from flowering-stage, HN65 from seedling-stage application. Optimizing MC concentration and timing enhances yield by modulating photosynthesis and assimilate partitioning in a cultivar-dependent manner.

Soybean plant architecture and stem mechanical properties are important determinants of lodging-resistance potential. To clarify the regulatory effects of mepiquat chloride (MC) applied at different growth stages and concentrations on soybean stem traits, two cultivars, Heinong 44 (HN44) and Heinong 65 (HN65), were used. Water-sprayed plants served as the control (MCK), and MC was applied foliarly at 50, 100, 200, or 400 mg/L at the V3 and R1 stages. Plant height, stem diameter, stem mechanical traits, and cell-wall components were measured. The effects of MC were strongly dependent on application timing, concentration, and cultivar. Following V3 application, 400 mg/L MC reduced the plant height of HN44 by 21.85% at R1; 200 mg/L MC increased basal stem diameter by 15.01% at R3 and fifth-internode diameter by 17.94% at R4. In HN65, 400 mg/L MC increased bending deflection by 27.01% at R1, whereas 100 mg/L MC increased cellulose content by 36.50%. In HN44, 100 mg/L MC increased lignin content by 77.39% at R2. Following R1 application, 400 mg/L MC increased bending deflection of HN44 by 29.40% at R2; 50 mg/L MC increased basal stem diameter by 20.85% at R6; and 400 mg/L MC increased stem breaking force by 36.23% at R4. In HN65, 200 mg/L MC increased hemicellulose content by 42.62% at R6. Correlation analysis showed a significant positive correlation between hemicellulose and lignin after both V3 and R1 applications, while some cell wall components were negatively correlated with stem bending deflection or breaking force. Overall, MC applied at different growth stages and concentrations regulated soybean plant architecture, stem mechanical properties, and cell wall composition; however, no single concentration was optimal across all cultivars and traits. V3 application produced a more pronounced early effect on plant architecture.