Agronomic performance and stability of seed, protein and oil yields of seven soybean cultivars determined in field experiments in Slovenia

The environment can have a crucial influence on soybean production in particular regions, even more so when production environments are different from breeding environments. Therefore, soybean cultivars must be evaluated in field trials at various locations in order to explore the duration of the growing period and capacity of yield, which is based on interactions between genotype and environment. Seven soybean cultivars originating from five European countries were evaluated for thousand-seed weight, seed, protein and oil yields and protein and oil contents in five environments in Slovenia. Yield stability of seed, protein and oil was determined in order to select best genotype. Results showed that cultivar and environment had a significant impact on all measured variables. In almost all tested environments the best seed, protein and oil yielding cultivars were ES Mentor (3425-5628 kg seed/ha, 1280-2192 kg protein/ha, 640.8-918.9 kg oil/ha) and NS Mercury (3468-5342 kg seed/ha, 1266-2071 kg protein/ha, 618.6-880.7 kg oil/ha). The highest average protein content was found in NS Favorit (41.0% of DW). Volma had the highest average oil content (20.2%). Three yield stability indices were used to assess yield stability; in terms of Shukla?s variance (?i2) and S square Wricke?s ecovalence (Wi2), Josefine turned out to have most stable seed and oil yields, while ES Mentor had most stable protein yields. Regarding Kang?s yield stability (YSi), which makes simultaneous selection for mean yield and stability and is therefore most relevant for practical usage, ES Mentor, NS Mercury and NS Favorit were selected as superior genotypes regarding stability of seed, protein and oil in this study. Correlation analysis of some chosen traits showed different interdependence between measured variables depending on the environment. As expected, protein and oil contents were negatively correlated, yet this was only significant in one environment. The results of this study pointed out that among the seven tested cultivars, ES Mentor, NS Mercury and NS Favorit were best genotypes and are highly recommended for usage in soybean production in Slovenia.