Exploring the Variability in Growth and Yield‐Related Responses of Soybean Under Rainfed Conditions in Central Europe

ABSTRACT To diversify cereal‐dominated rotations and increase protein supply for feed and plant‐based diets, soybean cultivation in nontraditional areas of Europe is encouraged. However, regional data and knowledge about nodulation, biomass and yield performance of different cultivars are still scarce. Field trials with nine soybean cultivars were implemented over 3 years in Berlin‐Dahlem, Germany. The main objective was to evaluate the responses and quantify growth, nodulation and yield of diverse feed‐ and food‐grade soybean cultivars under rainfed conditions. Nodulation varied across years, with minor differences among soybean cultivars. Nodule dry weight negatively correlated with numerous growth and yield‐related traits, including plant height, aboveground biomass, grain yield, pod number and harvest index, in comparison to nodule number. The average aboveground biomass ranged from 3101 kg ha −1 in the early food‐grade cultivar Tofina to 2521 kg ha −1 in the late food‐grade cultivar Siroca. Average grain yield ranged between 2317 and 1849 kg ha −1 for feed‐grade cultivars Acardia (early) and Antigua (very early), respectively. Environment contributed 87.0% to the variance in grain yield; year–cultivar interactions contributed 5.2%, whereas cultivar accounted only for 2.4%. There was considerable year‐to‐year variability in soybean yield, attributable to differences in climatic conditions, particularly during pod filling. The 2021 growing season, characterized by comparatively higher and uniformly distributed precipitation, lower evapotranspiration and reduced precipitation deficit during pod filling, had the highest soybean yield and superior grain quality. Our findings indicate that interannual precipitation variability represents a key constraint to achieving stable soybean cultivation in Northern Germany.