**3. Results**

In our study, all 13 quantitative traits had a normal distribution. The ANOVA indicated a statistically significant influence of soil type, years, cultivars, and the year × cultivar and year × soil type interactions for all 13 traits (Table 3). The soil type and soil type × cultivar interactions were not significant only for the tiller number. The year × soil type × cultivar was significant for all traits except panicle number (Table 3).



grains (pcs.) per panicle; Yield—mixtures yield; v. Share—the share of vetch in the mixture's yield (%); Panicle No.—number of oats panicles per m2; Tiller no.—number of oats' tillers; TWG—thousand grain mass of oats; TSW—thousand grain mass of vetch; Panicle g.w.—mass grains (g) per oats panicle; o. Plant No.—density of oats after spring emergence (pcs m2); v. Plant No.—density of common vetch (pcs m2) spring; o. Height—the height of oats canopy (cm). \* *p* < 0.05; \*\* *p* < 0.01; \*\*\* *p* < 0.001; d.f.–the number of degrees of freedom.

#### *3.1. Selected Biometric Features of the Mixture*

The average spring density of oat was similar for both soil types and the majority of oats' cultivars (Table 4). The cultivar factor as well as weather during emergency of the oat significantly affected its density.

**Table 4.** Oats' density in spring (pieces m<sup>−</sup>2) in mixture depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation; 4 ns—non-significant. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> The number of oat tillers in the mixtures was low and similar, regardless of the soil types (Table 5). However, the oat cultivars in the mixtures tilled differently, with cv. 'Celer', which developed the highest number of tillers, especially in 2013, and cv. 'Kasztan'—the lowest (1.14). The lowest oats' tillering was noted in 2014; it was 10% lower than in 2013.

**Table 5.** Number of oats' tillers in mixtures depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).



**Table 5.** *Cont.*

1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation; 4 ns—non-significant. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> Vetch density in the mixtures, as counted in spring, was ca. 30% lower than the planned one (Table 6). A higher density was noted on the H.C. soil than the S.L. soil. The vetch density depended on selected oats cultivar for the mixture and varied between 49.1 for cv. 'Furman' to 55.3 pieces m<sup>−</sup><sup>2</sup> for cv. 'Celer'. The highest vetch densities in the mixtures were found in 2013 year whereas the lowest in 2014.

**Table 6.** Vetch density in spring (pieces m<sup>−</sup>2) in mixture depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation; Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

#### *3.2. Yield of Mixtures*

On average, the mixture yielded 40% lower on Haplic Cambisol (H.C.), compared to Stagnic Luvisol (S.L.) (Table 7). The yield of three oat cultivars' grown with common vetch on the S.L. soil was 3.06—3.19 t ha−1, except for cv. 'Grajcar' that yielded significantly lower. On the H.C. soil, the yield of cv. 'Kasztan' was by 0.2—0.46 t ha−<sup>1</sup> higher compared

to other cultivars. The yielding of oat cultivars with vetch varied between years. The highest yields of the mixtures were in dry 2012, and the lowest, in regular 2014.

**Table 7.** Seed yield (t ha−1) of the mixture depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> The share of vetch seeds in the mixtures was variable. On average, it was 20% higher on the H.C. soil than the S.L. soil (Table 8). It was also highest in 2013 (65.7%) and the lowest–in a dry 2012 (19.6%). The vetch seed's share also depended on the selected oats cultivar and was the highest for cv. 'Grajcar', and the lowest for cv. 'Kasztan'.

**Table 8.** Share (%) of common vetch seeds in the mixture depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).



**Table 8.** *Cont.*

1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> The oat–vetch mixture's straw yield was significantly differentiated by the examined factors and their interaction (Table 9). A substantially higher straw yield was found on the S.L. soil (4.72 t ha−1) than the H.C. soil (3.72 t ha−1). Contrary to the grains' yield, the highest straw yield was recorded in 2014 (5.58 t ha−1), and the lowest in 2012 (3.13 t ha−1).

**Table 9.** Straw yield (t ha−1) for oats-vetch mixtures depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation; 4 ns—non-significant. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

#### *3.3. Selected Components of Yield Structure*

A substantially greater number of oats' panicles was found on H.C. soil (330 pieces m<sup>−</sup>2) than the S.L. soil (285 pieces m<sup>−</sup>2) (Table 10). On average, in the mixtures, the largest number of panicles developed cv. 'Celer' (344 pieces m<sup>−</sup>2) and the smallest—cv. 'Grajcar' (282 pieces m<sup>−</sup>2). Interestingly, during the dry 2012 year, oat developed almost twice more panicles than in the regular year 2014. In that year, regardless of the soil type, cv. 'Celer' developed the highest number of panicles (559—535 pieces m<sup>−</sup>2). The number

of oat panicles per m<sup>−</sup><sup>2</sup> decreased in the following years, most probably resulting from a continuous sequence of cereals in the crop rotation, and lack of fertilization.

**Table 10.** Number of oat panicles (pieces m<sup>−</sup>2) in the mixtures depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> Significantly more oats' grains per panicle (GPP), by 32%, were found on the S.L. soil, compared to the H.C. soil (Table 11). The number of GPP differed significantly for the oats' cultivars and was in a range of 10.5 for cv. 'Grajcar' to 14.0 for cv. 'Kasztan'. Contrary to the number of panicles per m<sup>−</sup>2, oat developed 13% more GPP in 2014 than in 2012.

**Table 11.** Number of grains (pieces) per oat panicle in the mixtures depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).



**Table 11.** *Cont.*

1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013,2014.

> The soil type significantly differentiated the mass of 1000 grains (MTG) of oat in the mixture with vetch (Table 12). The MTGs of the oats' cultivars in this experiment was lower than standard values (Table 2). A greater MTG was found for oats on the H.C. soil than the S.L. soil. The oat cultivars also differed in the MTG, which was in a range of 31.8–38.7 g for mixture with cv. 'Grajcar' and cv. 'Celer', respectively. In 2013, the oat MTG was 16% higher than in 2012.

**Table 12.** 1000-grain mass (g) of oat in the mixture with vetch depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> The significant relationships of the mass of grains per oats' panicle were similar to the relationships presented for the MTG of oats (Table 13).


**Table 13.** Mass grains (g) per oat panicle in the oat–vetch mixture depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).

1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> Relative to oats, the mass of 1000 seeds (MTS) of vetch was 12% higher on the S.L. soil than the H.C. soil (Table 14). The MTS of vetch was also considerably influenced by the cultivar of oat, as the mixture companion. The highest MTS of vetch was found in the mixture with oat cv. 'Grajcar', and the lowest in the mixture with oat cv. 'Kasztan'. Moreover, the MTS of vetch varied significantly over the years of the study. The highest MTS of vetch was in a regular 2014, and the lowest in a dry 2012.

**Table 14.** 1000-seed mass (g) of vetch cv. 'Hanka' of the mixture depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).



**Table 14.** *Cont.*

1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

#### *3.4. Protein Content in Oat Grains and Vetch Seeds*

The soil type significantly differentiated the total protein content in oat grains (Table 15). A 5% higher protein content was found in grains of oats grown in H.C. soil than the S.L. soil. The protein content differed among the oat cultivars in the mixtures and was in a range of 94.4 for cv. 'Kasztan' to 107 g kg−<sup>1</sup> for cv. Furman. On average, a 39% higher protein content was found in the grains of oats in 2013 than in the dry 2012 year.

**Table 15.** Total protein content in oat grain (g kg−1) grown in the mixtures, depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> The type of soil significantly affected the vetch seeds' protein content, which was higher on the S.L. soil (Table 16). High protein content in vetch seeds was found in the mixture with oats cv. Furman, which was also rich in protein. The same relationship was found for the lowest protein content in the vetch/oat mixture, which was in the one with

oat cv. 'Kasztan' (Table 15). On average, the highest protein content in vetch seeds was found in 2013, and the lowest in 2014.

**Table 16.** Total protein content in vetch seeds (g kg−1) grown in the mixtures, depending on the soil type (factor I), oat cultivar (factor II), and study years (factor III).


1 Mean for the soil type, regardless of the oat cultivar; 2 Mean for the year 2012–2014; 3 S.D.—standard deviation. Homogeneous groups were created for the main factors. According to Tukey's test, mean values marked with the same letters do not differ significantly (*p* ≤ 0.05). Capital letters (A and B) for mean values of the first factor levels—soil types, small letters (a, b, c) for mean values of the second-factor levels—oats cultivars and x, y and z letters for the third-factor levels—study years were chosen. The three-factor ANOVA—first-factor, soil type: Stagnic Luvisol and Haplic Cambisol; second-factor, oat cultivar: 'Celer', 'Furman', 'Grajcar', 'Kasztan'; third-factor, years: 2012, 2013, 2014.

> The canonical variate analysis (CVA), which included all the tested traits, was applied to extract the factor that influenced the overall state of the oat–vetch mixtures the most (Figure 4). The first two canonical variates explained jointly 81.19% of the total variation between the treatments. The greatest, significant linear relationship was found for protein content in oat grains (g kg−1) and a share of common vetch seed in the mixture's yield (positive dependency). The significant negative dependencies were found for the mixtures' yield, the number of oats panicles per m<sup>−</sup>2, and the mass of grains per oat panicle. The second canonical variate was significantly positively correlated with the number of oat panicles per m<sup>−</sup><sup>2</sup> and the density of oat at spring. The negative correlation was found for the number of grains per oat panicle, a share of vetch seed in the mixture's yield, and the 1000-grain mass of oat.

> The diversities in all traits, as measured with Mahalanobis distances, are presented in Table 17.

**Figure 4.** Distribution of combinations of treatments in the two first canonical variates. Abbreviations: S.L.—Stagnic Luvisolor, H.C.—Haplic Cambisol; C.—'Celer', F.—'Furman', G.—'Grajcar', K.—'Kasztan'; 12–14—years 2012–2014.

The CVA analysis pointed to the year (weather conditions) as a main differentiating factor for the mixture's performance. The best for the mixtures turned to be the year 2013, and the worst—the dry year 2012. Moreover, Haplic Cambisol was better for the tested mixtures than the Stagnic Luvisol. The analysis also revealed that among the studied four cultivars of oats, the best for mixing with vetch cv. 'Hanka' was cv. 'Furman' and cv. 'Grajcar'.


**Table 17.** Mahalanobis distances between pairs of combinations of three studied factors.
