Improvement of Premium Oil Soybean Variety Heinong 551 with Integrating Conventional Hybridization and Gamma Radiation

Meeting the growing demand for vegetable oil while promoting agricultural sustainability in Northeast China requires developing high-yield, high-oil-content soybean varieties. We present the comprehensive development and evaluation of Heinong 551, an innovative soybean variety created through an integrated approach of conventional breeding methods and radiation-induced mutation techniques. The breeding program began with hybridization between Heinong 44 (the maternal parent) and Hefeng 47 (the paternal parent), followed by targeted exposure to ⁶⁰Co gamma radiation at 130 Gy to induce beneficial mutations. Using systematic selection protocols over five generations from 2012 to 2016, we identified superior lines that underwent rigorous multi-location testing across seven sites in Heilongjiang Province during 2020-2021. Field evaluation results showed consistent performance, with Heinong 551 achieving average yields of 2901 kg/ha and 3142 kg/ha in those years, representing significant gains of 10. 6% and 11.0. 0% compared to standard control varieties. The cultivar maintained stable phenological traits with a reliable 120-day maturation period and demonstrated strong environmental adaptability across different growing conditions. Biochemical analysis revealed excellent nutritional value, with 39.45% crude protein and 21.69% crude fat, reaching a combined protein-fat percentage of 61.14%. Quality tests confirmed superior seed integrity, with sound seed rates over 97% and minimal pest or disease damage. Disease resistance assessments showed moderate tolerance to gray leaf spot while maintaining excellent overall plant health, with no signs of viral infections or nematode infestations during testing. Heinong 551 has received official approval for cultivation in Heilongjiang Province' s second accumulated temperature zone, characterized by thermal units ≥2550 °C above a 10 °C threshold. This represents significant progress in high-oil soybean variety development, illustrating the success of combining traditional breeding methods with modern mutation technology.