Environment and not genotype drives soybean yield stability in Northern Germany

Abstract

Soybean [Glycine max (L.) Merr.] is a major plant protein source worldwide, and its cultivation in central and northern Europe is still emerging. To understand the influence of the environment in the northern latitudes and its interactions with different soybean genotypes, a 3-year multi-location trial was carried out in Northern Germany. The objectives were to (i) quantify the grain yield and stability of six soybean genotypes across eight environments using the additive main effect and multiplicative interaction and best linear unbiased prediction models to identify superior genotypes as well as optimal environmental conditions for growing soybeans in northern latitudes, and (ii) assess the genotype-environment interaction on soybean grain yield, crude protein, and protein yield to explore the factors contributing to yield variability. The mean soybean grain yield was 2060 kg ha⁻¹, and it varied among locations and across years. A large portion of the total variance in all parameters was explained by environment (67.6%–82.8%), followed by genotype-environment interaction (7.7%–14.6%), while a small portion was attributed to genotypes (1.3%–10.5%). The growing conditions at site Müncheberg produced a stable soybean yield but were less productive than sites Dahlem and Dedelow. Regular precipitation in July and August corresponded with increased grain yield. The stability models ranked the feed-grade cultivar Merlin as superior in terms of stability and performance. In contrast, the food-grade cultivar Comandor may be risky for grain production in rainfed conditions. The study highlighted soybean's agronomic potential in northern latitudes and the influence of the prevailing environment on yield and stability.