## 4 Discussion  
### Proximate Composition  
Most of the literature data concern the composition of mustard seeds of individual species, and not plants in vegetative stages, such as young shoots. The presented research results are often a novelty in the literature on the subject. An increase in the share of dry mass in white mustard plants was found depending on the time of harvest. After about 1.5 months of vegetation, e.g., 45 days after sowing, the plants obtained an average of about 17.72% DM. Similarly, [PERSON] and [PERSON] [41] showed that the content of dry mass in the white mustard increases with the extension of the vegetation period of the plant. Mustard of the Nakielska cultivar, harvested after 45 days of vegetation, contained on average 10% of dry mass, and after 108 days of vegetation, on average 32.4% of dry mass. [PERSON] and [PERSON] [42] assessed the DM content in white mustard plants sown in stubble catch crops in the first decade of August. After about 2 months, they obtained a dry mass content of 15.21-16.79%. A higher content of dry matter  
Figure 3: Example of chromatogram obtained for mustard cultivar Borowska. (**A**) Thirty-one days after sowing. (**B**) Thirty-eight days after sowing. (**C**) Forty-five days after sowing. \({}^{\star}\) The identification was made based on the Reaxys platform and references [36; 37; 38; 39; 40]. in our research may result from the use of different genotypes and the time of observation. Since white mustard is a long-day plant with a strong photoperiodic reaction [43] in spring sowing, it hurries to produce inflorescences faster, increasing the share of dry matter. In turn, research conducted by [PERSON] et al. [27] using monthly plants of two varieties of red mustard indicates a slightly lower dry matter content compared to those presented in this work (on average, after about 1 month, 10.38% DM), within the range 8.4-6.51%. This may be due to differences in genotypes, soil moisture, temperature during plant vegetation and applied fertilization. The obtained dry mass values of green mustard plants in the analyzed harvest dates are similar to data from the literature for other commonly used green vegetables. For comparison, [PERSON] et al. [44], in frozen Brussels sprouts (_Brussels oleracea_), determined about 14 g/100 g of dry mass content, and according to a study by [PERSON] et al. [45], celery leaves contained on average 21.99% of dry mass in leaf blades and 12.83% of dry mass in petioles. These authors also observed an increase in the share of dry mass in celery in the second harvest. The protein content in green white mustard plants in the presented research results ranged from 22-96-36.28% DM. [PERSON] and [PERSON] [46] emphasize the high value of green leafy plant proteins due to the presence of a polypeptide complex: RUBISCO. RUBISCO is rich in essential amino acids, with typically eight of the designated nine percent meeting the FAO nutritional criteria. No data on the basic composition of white mustard plants were found in the literature, but similar studies were conducted by [PERSON] et al. [27] using monthly plants of two varieties of red mustard. In the cited studies, the crude protein content ranged from 1.66-1.81% for one cultivar and from 1.64-1.93% for the other. [PERSON] et al. [43] report that 140 g of chopped mustard leaves contained 2.56 g of protein (without specifying the species used for the study). According to [PERSON] et al. [47], shoots and leaves of common mustard, depending on the cultivar, contained from 1.1 g to 4.4 g of protein per 100 g of fresh weight. After converting the averaged results into protein content in dry matter, a result of 22.6% protein was obtained, similar to that for the white mustard cultivar Bamberka (31 day after sowing--22.96). The green parts of white mustard, therefore, contain more protein (22-96-36.28%) than common mustard, which is common in Asian countries. In the tested cultivars of white mustard, the protein content depended on both the date of harvest and the cultivar used.