Soybean (Glycine max) is one of the most important and valuable crops globally and has been a subject of extensive research for agronomists and plant breeders. As a legume crop, soybean enriches the soil with nitrogen and also serves as human food and livestock feed. This research paper aims to discuss various aspects of soybean production, pests and diseases management, breeding efforts, and future prospects through an in-depth review of published literature.
Soybean Production Systems and Management: Soybean is grown worldwide under diverse climatic and edaphic conditions ranging from tropical to temperate regions. Based on latitude, day length, and temperature requirements, four different soybean maturity groups (0000-IV) have been identified which determine the suitable regions for respective groups. Timely sowing, varietal selection matching local conditions, proper spacing and plant population, balanced nutrition, weed, disease and pest management are essential agronomic practices for achieving high productivity. No-till direct drilling is also being adopted by some farmers for maintaining soil health and moisture. Soybean-wheat or corn rotation is commonly practiced to benefit both the crops through nitrogen fixation and weed management. Harvest is mostly done manually in developing countries while mechanical harvesters are used in mechanized farming systems. Post-harvest management includes timely drying, cleaning, grading and storage to minimize losses.
Soybean Pests and Diseases: Among major production constraints, insect pests cause an estimated loss of 7-15% globally each year. Important defoliators are velvetbean caterpillar, Mexican bean beetle, soybean looper etc. Pod feeders include stink bugs, grasshoppers, bagworm etc. Other pests are soybean aphid, root lesion nematode, stem canker, charcoal rot fungus etc. for which host plant resistance, biocontrol agents, and pesticides are employed depending on pest pressure and economic threshold limits. Major diseases are root and stem rot caused by fungi like Phytophthora, Fusarium, Rhizoctonia affecting roots and lower stem. Other foliar diseases include bacterial blight, downy mildew caused by fungi, soybean mosaic and nodulation caused by viruses. Breeding for resistance and rotation of fields are preferred disease management strategies. Integrated pest and disease management approaches combining different control tactics are imperative for sustainable production.
Soybean Breeding: Conventional hybridization and selection led to development of high-yielding cultivars with desired maturity, plant architecture and other agronomic traits. Selection pressure on biotic and abiotic stresses also enhanced disease/pest resistance. Marker-assisted selection using DNA markers is speeding up introgression of valuable genes. Genetic enhancement through mutation breeding and genetic engineering is focusing on developing high protein, vitamins and minerals enriched soybeans. Drought and salinity tolerance, herbicide and pesticide resistance are other important traits being incorporated. Genomic tools are accelerating characterization and mapping of valuable yield and quality genes. CRISPR and other new breeding technologies now enable precise genome editing promised to revolutionize soybean improvement. Public and private sector plant breeding programs globally are constantly engaged in developing high-yielding varieties for diverse agro-climatic zones.
Future Prospects: FAO projects global soybean demand to rise by 60% due to population and economic growth by 2050. To meet this rising demand while ensuring environmental sustainability, the future focus should be on developing tolerant/resilient varieties through breeding, raising productivity through better agronomic practices and precision farming, adopting protected cultivation, introducing alternate uses like biofuel and industrial applications, promoting processing and value addition, improving seed replacement rate and extension services for smallholders especially in developing nations. Application of nanotechnology, artificial intelligence, sensors, robotics and automation also hold great promise to transform soybean production systems in the near future. To capitalize on these opportunities, major investments are required in R&D, infrastructure, capacity building, market access and public-private partnerships globally. Sustainably meeting the projected demand for soybean as a multi-purpose crop of global significance will be a defining challenge for the agricultural research and development sector.