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Effect of varied nitrogen sources and type of cultivation on the yield and physicochemical parameters of flowering Chinese Cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee)
The aim of our study was to determine the effect of various nitrogen sources (NH4NO3 (N, 34%), Ca(NO3)2 (N, 15.5%; Ca, 18%), Mg(NO3)2 (N, 11%; Mg, 12%), NaNO3 (N, 15%; Na, 25%) and urea (N, 46%)) and increasing the intensity of N nutrition with these fertilisers (50, 70, and 90 mg N·dm−3) on the yield and quality of flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee). The plants were grown in two different soilless systems, namely pot cultivation (substrate system—mixture of peat and sand) and hydroponic cultivation. The quality of plants was expressed as macro- and microelement contents, pigment contents, antioxidant activity and phenolic content. It was observed that the yield of flowering Chinese cabbage was about 43–70% higher in the hydroponic system than in the substrate. The N source and N nutrition affected the yield volume. The highest mean yield was observed in pot cultivation after fertilisation with Mg(NO3)2 and in hydroponics with Ca(NO3)2. We found a rather high tolerance of flowering cabbage to sodium and an excessive content of ammonium in the nutrient solution. The nitrogen source and N doses modified plant contents of macro- and microelements (N, P, K, Ca, Mg, Na, Fe, Mn, Zn and Cu) and other quality parameters of plants. In pot cultivation, the highest element contents as well as the highest antioxidant activity were obtained after fertilisation with Mg(NO3)2 at N-70 and N-90. The highest pigment contents (chlorophylls and carotenoids) were obtained in the samples treated with urea at the N-90 dose. Those samples were also characterised by a high Mn content. Generally, the pigment content in the pot system positively correlated with the Mn content in leaves, the microelement which is involved in the process of photosynthesis, but it did not correlate with colour coordinates. In the hydroponic system, the highest pigment contents were observed in the samples treated with Mg(NO3)2 at the N-70 dose. Generally, in hydroponics, chlorophyll levels positively correlated with Ca levels in the aboveground parts of the plants. Additionally, the content of Chl b inversely correlated with L* and b* values. In hydroponic systems, the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) activity was observed after treatment with NH4NO3 at the N-70 and N-90 doses and it did not correlate with phenolic content but rather with pigment content. In conclusion, both the intensity of N nutrition and the fertiliser applied can significantly modify the yield of plants and their quality parameters. For pot cultivation, the most effective fertiliser was Mg(NO3)2 at the N-70/N-90 doses, while for hydroponic cultivation, it is difficult to indicate the most effective fertiliser as the responses varied depending on the method of fertilisation.
Antioxidative Status and Meat Quality Traits as Affected by Dietary Supplementation of Finishing Pigs with Natural Phenolics
This work investigated the effect of a plant-based phenolic supplement on the color, myoglobin forms, lipid oxidation, and antioxidative status of fresh and stored (10 days at 4 °C) meat (Longissimus thoracis et lumborum), as well as the antioxidative status of the blood and liver. The sensory quality of the meat was also evaluated for color, aroma, texture, juiciness, and palatability. Twenty-four finishing pigs, divided into two groups, were fed a basal diet and a diet with a phenolic supplement (0.1%). The supplementation increased the redness of the meat (+36% for a* and +28% for redness index), the myoglobin (Mb) content (+7%), the antioxidant activity, and the juiciness. The treatment increased the antioxidant status of meat, reflected by superoxide dismutase (SOD) activity and total glutathione (GSH + GSSG). The catalase and SOD activities and GSH + GSSG of the blood and liver were also elevated in the supplemented samples when compared to the control group. A significant effect of time was observed for all tested parameters (pH, color attributes, Mb forms, the antioxidant activity, lipid oxidation) except for the Mb content. For the stored samples, only TBARSs (thiobarbituric acid reagent substances) were affected by the diet. The slope of the plot for TBARS changes with time was significantly different between the control and treated groups (p = 0.017), which indicated a significant effect of dietary supplementation. A higher rate of lipid oxidation was observed in the control samples.
The Effect of Various Foliar Treatments and Nitrogen Nutrition Levels on the Yield and Physicochemical Parameters of Flowering Chinese Cabbage
Flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) is an original leafy vegetable from China, and it is a valuable source of bioactive compounds. In the literature, there are no practical recommendations for the cultivation and fertilization of this species. Our study aimed to investigate the effect of nitrogen nutrition levels (70 and 90 mg N per dm3) and various foliar treatments (Se, Si, Li, V, and SA—salicylic acid) on the quantity of the yield and the quality of flowering Chinese cabbage grown in two varied soilless cultivation systems: under pot cultivation (mixture of peat and sand) and hydroponic culture. In conducted studies, we have confirmed the hypothesis that the intensity of nitrogen nutrition and the application of foliar spraying modify the yield of plants, both the quantity and the quality aspects. The factors under analysis had a diversified and multidirectional influence on the yield, growth, and quality of the plants. The results varied between the two cultivation systems. This was proved by the PCA (principal component analysis). Generally, the plants grown in the hydroponic system were characterized by higher yields than those grown in pot cultivation. This was found to be a stimulating effect of N nutrition on the content of that nutrient in the aerial parts of the plants. Plants sprayed with Si and Se were characterized by a high content of Chl a, Chl b, carotenoids, and relatively high antioxidant activity. Finally, the samples subjected to different foliar spray treatments could be classified into appropriate groups based on the quality parameters.