Salinization is a global agricultural problem with many negative effects on crops, including delaying germination, inhibiting growth, and reducing crop yield and quality. This study compared the salt tolerance of 20 soybean varieties at the germination stage to identify soybean germplasm with a high salt tolerance. Germination tests were conducted in Petri dishes containing 0, 50, 100, 150, and 200 mmol L⁻¹ NaCl. Each Petri dish contained 20 soybean seeds, and each treatment was repeated five times. The indicators of germination potential, germination rate, hypocotyl length, and radicle length were measured. The salt tolerance of 20 soybean varieties was graded, and the theoretical identification concentration was determined by cluster analysis, the membership function method, one-way analysis of variance, and quadratic equation analysis. The relative germination rate, relative germination potential, relative root length, and relative bud length of the 20 soybean germplasms decreased when the salt concentration was >50 mmol L⁻¹, compared with that of the Ctrl. The half-lethal salt concentration of soybean was 164.50 mmol L⁻¹, and the coefficient of variation was 18.90%. Twenty soybean varieties were divided into three salt tolerance levels following cluster analysis: Dongnong 254, Heike 123, Heike 58, Heihe 49, and Heike 68 were salt-tolerant varieties, and Xihai 2, Suinong 94, Kenfeng 16, and Heinong 84 were salt-sensitive varieties, respectively. This study identified suitable soybean varieties for planting in areas severely affected by salt and provided materials for screening and extracting parents or genes to breed salt-tolerant varieties in areas where direct planting is impossible. It assists crop breeding at the molecular level to cope with increasingly serious salt stress.

Soybeans are the main sources of oil and protein for most of the global population. As the population grows, so does the demand for soybeans. However, drought is a major factor that limits soybean production. Regulating soybean response to drought stress using mepiquat chloride (MC) is a feasible method; however, its mechanism is still unclear. This study used PEG-6000 to simulate drought stress and quantitative proteomic techniques to reveal changes in Heinong44 (HN44) and Heinong65 (HN65) subjected to drought following the application of 100 mg/L of MC. The results showed that SOD in HN44 did not change significantly but decreased by 22.61% in HN65 after MC pretreatment, and MDA content decreased by 22.75% and 21.54% in HN44 and HN65, respectively. Furthermore, MC improved the GSH–ASA cycle and simultaneously promoted the Calvin cycle process to enable the plant to maintain a certain carbon assimilation rate under osmotic stress. In addition, MC upregulated some proteins during gluconeogenesis and starch metabolism and increased soluble sugar content by 8.41% in HN44. MC also reduced ribosomal protein abundance, affecting translation and amino acid metabolism. In summary, MC improved GSH–ASA cycle and Calvin cycle under stress to alleviate oxidative damage and maintain crop growth. Our study is the first to report the mechanism of MC regulation in soybean under osmotic stress, providing new insights for the rational application of MC in soybean.

Nitric oxide (NO) plays a significant role in plant drought resistance. However, the effects of the exogenous application of NO to crops under drought stress vary within and among species. In this study, we explored the influence of exogenous sodium nitroprusside (SNP) on the drought resistance of soybean leaves in the full flowering stage using two varieties: drought-tolerant HN44 and non-drought-tolerant HN65. Spraying SNP on soybean leaves at the full flowering period under drought stress improved the NO content in soybean leaves. The activities of nitrite reductase (NiR) and nitrate reductase (NR) in leaves were affected by NO inhibition. The activity of antioxidant enzymes in leaves increased with the extension of SNP application time. Contents of osmomodulatory substances, including proline (Pro), soluble sugar (SS), and soluble protein (SP) increased gradually with the extension of SNP application time. The malondialdehyde (MDA) content decreased as the NO content increased, thus reducing membrane system damage. Overall, spraying SNP reduced damage and improved the ability of soybean to cope with drought. This study explored the physiological changes of SNP soybean under drought stress and provided theoretical basis for improving drought-resistant cultivation of soybean.

Background: Drought is the main restricted agent for growth and development of soybean and the physiological characteristics of different parts of soybean leaves changed significantly. Methods: To explore the impacts of drought stress on the physiological characteristics of leaves in different parts of soybean, in this study, Williams 82 was used as the experimental material and drought stress was simulated by a watering nutrient solution containing 10% PEG-6000. Under different treatment time conditions, the superoxide dismutase (SOD) activity and proline (Pro) content in different parts of soybean leaves were determined. Result: The results indicate that the SOD activity and Pro content in the upper and bottom leaves of soybean increased significantly under drought stress conditions and with the increase in drought stress time, the SOD activity in the upper and bottom leaves of soybean increased first and then declined and the content of Pro increased gradually. In general, soybean relief drought damage by increasing SOD activity and Pro content under drought stress. This study offered the theoretical foundation for exploring the mechanism of soybean drought resistance.

Background: Soybean is the most important oil crop globally; however, droughts are expected to seriously affect the growth and development of soybean in the context of climate change. Methods: In this study, polyethylene glycol (PEG) was used to simulate drought to explore the regulation of proline metabolism in soybean leaves under different degrees of drought stress at the seedling stage. Result: The results showed that the activities of ornithine aminotransferase and Δ1-pyrroline-5-carboxylate synthetase increased while the activities of proline dehydrogenase decreased with an increase in drought stress. During the same number of treatment days, the higher the degree of drought stress, the greater the increase or decrease in enzyme activity. The content of leaf proline increased gradually with an extension in stress time at PEG concentrations of 5% and 10%, first increased and then decreased at PEG concentrations of 15% and 20% and the peak value appeared on the 7th and 9th day, respectively.

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.