Environmental effects on soybean (Glycine Max (L.) Merr) production in Central and South Germany

The cultivation area of soybean (Glycine max (L.) Merr) is increasing in Germany as a way to ensure self-sufficiency through its use as feed and food. However, climatic conditions needed for soybean cultivation are not appropriate in all parts of the country. The objective of this study was to determine the influence of solar radiation, temperature, and precipitation on soybean seed productivity and quality in central and south Germany. A multi-factorial field trial was carried out with three replicates at four locations in 2016 and five locations in 2017, testing 13 soybean varieties from the maturity groups MG 00 and MG 000. Considering all the tested factors, “variety” was highly significant concerning protein content (Ø 41.1% dry matter (DM)) and oil content (Ø 19.1% in DM), but not seed yield (Ø 40.5 dt ha−1).The broad sense heritability of protein content was H2 = 0.80 and of oil content H2 = 0.7. Protein and oil content were significantly negatively correlated (r = −0.82). Seed yield was significantly positively correlated with solar radiation (r = 0.32) and precipitation (r = 0.33), but significantly negatively with Crop Heat Units (CHU) (r = −0.42). Over both experimental years, varieties from maturity group MG 00 were less significantly correlated with the tested environmental factors than varieties from maturity group MG 000. None of the environmental factors tested significantly increased the protein or oil content of soybean. In growing areas with heat periods during ripening, protein content tended to be higher than in cooler areas; in areas with high solar radiation during flowering, protein content tended to be reduced.