## 3 Results  
The content of dry mass and the proximate composition of plants of the white mustard varieties harvested in various stage of development are presented in Table 1. \begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Treatment**} & \multirow{2}{*}{**Cultivar**} & \multicolumn{3}{c}{**Harvest Date the Number of Days after Sowing**} & \multirow{2}{*}{**Means for Cultivar**} \\  & & **31** & **38** & **45** \\ \hline \multirow{4}{*}{Dry mass [g/100 g FM *]} & Warta & 9.99 \(\pm\) 0.51 a & 11.22 \(\pm\) 0.62 a & 17.40 \(\pm\) 2.39 a & 12.87 \(\pm\) 3.60 A \\  & Bamberka & 10.33 \(\pm\) 1.05 a & 11.13 \(\pm\) 2.00 a & 17.95 \(\pm\) 0.85 a & 13.14 \(\pm\) 7.37 A \\  & Borowska & 10.80 \(\pm\) 1.43 a & 10.36 \(\pm\) 0.48 a & 17.80 \(\pm\) 0.71 a & 12.99 \(\pm\) 3.62 A \\ \cline{2-6}  & Means for & & & & \\ harvest time & 10.38 \(\pm\) 1.06 A & 10.90 \(\pm\) 1.23 A & 17.72 \(\pm\) 1.45 B & \\ \hline \multirow{4}{*}{Protein} & Warta & 36.28 \(\pm\) 1.07 f & 34.80 \(\pm\) 1.13 e & 29.53 \(\pm\) 0.76 c & 33.53 \(\pm\) 3.16 C \\  & Bamberka & 22.96 \(\pm\) 0.47 a & 33.27 \(\pm\) 1.00 e & 24.39 \(\pm\) 0.88 a & 26.87 \(\pm\) 4.82 A \\ \cline{1-1}  & Borowska & 33.82 \(\pm\) 1.58 e & 26.12 \(\pm\) 1.53 b & 31.40 \(\pm\) 1.68 d & 30.44 \(\pm\) 3.65 B \\ \cline{1-1} \cline{2-6}  & Means for & & & & \\ harvest time & 31.82 \(\pm\) 6.13 B & 31.40 \(\pm\) 4.11 B & 28.44 \(\pm\) 3.27 A & \\ \hline \end{tabular}
\end{table} 
Table 1: Dry mass and proximate composition of different varieties of white mustard [g/100 g DM]. Dry mass content was affected by time of harvest. Forty five days after the sowing, the plants obtained a higher content of dry mass as compared to plants harvested in thirty-one and thirty-eight day after sowing. There were no differences between the mustard varieties in terms of dry mass content. The protein content in white mustard plants depended on both the date of harvest and the cultivar (Table 1). In the 45 days after sowing, the concentration of proteins was significantly lower as compared to the 31 and 38 days after sowing. The double-improved Warta cultivar with an average content of 33.53% DM was the richest in protein. It was also found that individual cultivars reacted slightly differently in terms of the content of this component to the term of harvest (Table 1). Statistically significant differences in crude fat content were found in the tested cultivars of white mustard. The green plants of the Warta cultivar were characterized by a lower crude fat content compared to the Bamberka and Borowska cultivars. The content of the total carbohydrates significantly increased in mustard plants 38 and 45 days after sowing. However, the reaction to the date of harvest of individual varieties was slightly different, because the Borowska variety reached the highest total carbohydrate content during the second harvest. Bamberka turned out to be the cultivar richest in total carbohydrates with an average content of 57.02% DM. The content of ash significantly decreased with the growth of the plant and, thus, the delay of the harvest date (Table 1). However, a slightly different effect of each cultivar to the harvest time was observed. The highest ash content was found in the Borowska cultivar from the first harvest, and the lowest in the Warta harvested after 45 days of sowing. Table 2 presents the results of antioxidant activity determined by the ABTS and FRAP methods and the content of total polyphenols.