Resumen
Soybean yields are influenced by numerous factors, including environmental conditions, location, and agricultural practices. Sowing date affects plant growth, development, and yields, and it plays a particularly important role in soybean cultivation. The optimal sowing date should be selected based on soil temperature, precipitation, and rainfall distribution in a given region. The aim of this study was to determine the effect of various sowing dates (I?early, II?optimal, III?late) on the time from sowing to emergence of soybean seedlings, length of the growing season, morphological traits of soybean plants, yield components, and seed yields of soybeans grown in north-eastern Poland. Sowing date considerably affected the time from sowing to the emergence of soybean seedlings and seed yields. In north-eastern Poland, soybeans should be sown in the first half of May to minimize the risk of ground frost damage, which can occur even in late May. Sowing date also influenced soybean yields. In north-eastern Poland (Region of Warmia and Mazury), yields were maximized when soybeans were sown late (in mid-May), which was decisively influenced by climatic conditions, mainly temperature. The linear regression analysis revealed that the length of the growing season was correlated with the seed yields of soybeans sown on different dates.