## 3 Discussion
These results indicate that number of pods per plant has a significant influence on yield. The positive correlation of PPP with PH and the negative correlation of GPP with PH, both observed at IFVCNS, is similar to [35], suggesting that the height of the plant could affect the number and size of seeds. Furthermore, the negative correlation between PH and PoL and the positive correlation between PoL and GPP observed at IFVCNS may indicate an indirect negative correlation between height and grains per pod. A significant negative correlation was expressed between TSW with GPP, PPP, and SPP for both trial sites, and GPP with PL (in the IFVCNS trial). SPP and FL were positively correlated only in the Agro Seed trial. PC was significantly negatively correlated with TSW only in the IFVCNS trial, unlike the results of [36], who noted positive correlations between these two traits. Our results for the IFVCNS trial, similar to [37], showed that in pea, the relationship between seed yield and seed weight per plant is always positive, regardless of the environment and the genetic background, which implies that the relationship between seed protein content and seed yield is almost always negative. Correlations between remaining pairs of traits mainly were low and non-significant in both years, which might indicate the presence of nonlinear interaction between traits [38]. Correlation of a single trait between years was analyzed. A low correlation between years might suggest a higher genotype by environment (GxE) interaction [15]. Thus, it can be concluded that traits with lower correlation between 2019 and 2020, such as PPP, SPP, PL, and SWPP, were influenced by environmental factors, while TSW, PoL, GPP, and PH were less affected. Similar findings were observed by [15] and [19], which also detected lower GxE interactions for TSW and higher interactions for SPP. The lowest correlation was observed for FL, which might indicate genotype reaction to agro-ecological conditions (high GxE). This might be influenced by the fact that the varieties, wild accessions, and landraces included in the assessed germplasm collection originated from different climatic conditions. Since the correlations of all examined traits in two years were positive, it can be concluded that the studied set of genotypes did not have strong reactions to different agro-ecological factors. Despite the absence of clearly separate groups among pea genotypes based on plant type, comparison among groups by different subtypes (forage, dry, and vegetable) indicated their differences in phenotypic traits based on PCA, so deviations in morphological characteristics between groups comparing trial sites can still be visible. Based on the IFVCNS trials, where the grouping of most landraces is visible on the PCA diagram (Figure 5, left), grouping could result from landrace characteristics to have a higher plant height and smaller grains. Clustering can also be seen for some of the varieties and breeding lines. However, both these groups consist of genotypes from different climates and origins and different uses. Further studies, similar to [15] and [39], performed at the molecular level, could show a more detailed grouping of these genotypes. Comparing type by use, in the IFVCNS trial, clustering can be seen mostly for the dry pea subtype, followed by the forage subtype (Figure 6, left). Dry pea varieties are characterized by small number of seeds per pod, large grains, and about 20-25% protein content [40; 41], while forage peas are mainly characterized by small grains, indeterminate type, and 17-24% protein content [41; 42]. Similar clustering can be seen in the Agro Seed trial, with a less visible structure. Wild and landrace types are clustered together (on the right). There were marked phenotypic differences between the wild peas (climbing, low lodging resistance, indeterminate growth) and commercial pea varieties (dry pea, forage). However, there was significant variation in the traits themselves, which was confirmed by analysis of variance.