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Cultivating crops under saline conditions is of high importance due to global fresh water shortage for irrigation. Crithmum maritimum is a halophytic plant that has a long history of human consumption and was suggested as a cash crop for biosaline agriculture. Our results highlight variations existing among Crithmum maritimum genotypes from different geographic origins regarding salt-induced changes in plant growth, flowering behavior and leaf metabolites with nutritional value. Our results indicate that genotypic characteristics should be taken into account when evaluating wild plant species for future crop cultivation.

Aster tripolium L. is a salt marsh halophyte that has recently gained interest as a cash crop vegetable. Leaf yield and quality were investigated in plants grown with salinity in experiments with Perlite in pots and in plots on dune sand. Plants were repetitively harvested in a 14-day cycle. A. tripolium irrigated with 50 mM NaCl exhibited the highest yield when grown in pots, whereas in the plot experiment no significant differences in biomass accumulation occurred up to 80 mM NaCl in the irrigation water. Chemical leaf composition changed with salinity, exhibiting higher levels of electrical conductivity, total soluble solutes and the non-enzymatic antioxidant compounds ascorbic acid and polyphenols compared with control plants grown without NaCl supplementation. Using the repetitive harvest regime, leaf chlorosis occurred, a symptom shared by deficiencies in either nitrogen or iron. Comparative applications of five iron chelate formulations in plants grown with 50 mM NaCl in pots revealed improved leaf colour and chlorophyll content for only two of the applied Fe-chelates. Concomitantly with leaf colour restoration, the activity of nitrate reductase, the first enzyme during nitrate assimilation, which requires heme-iron for its proper function, increased 3-fold as a result of the iron treatment in the plot experiment. Importantly, the enhancement of nitrate reductase activity was associated with a considerable decrease in the leaf nitrate concentration. Therefore, we concluded that iron deficiency, in addition to leaf chlorosis, reduces A. tripolium leaf quality as a vegetable by increasing the leaf nitrate content. Furthermore, nitrate reductase (NR) activity levels in A. tripolium leaves may act as an indicator of iron deficiency that manifests itself as reduced nitrate content owing to the higher NR activity upon proper iron nutrition. These results demonstrate the importance of salinity level and the application of an appropriate iron-chelating formulation to generate marketable yields of Aster tripolium leafy vegetable when grown commercially on dune sand.

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In the present, the consequences of nitrate pollution of the environment are very pronounced. In humans and animals, microorganisms can reduce nitrates to nitrites, which cause cancer. Purified and homogeneous xanthine oxidase (XO) of cow's milk can restore these compounds, which makes the article extremely relevant. The purpose of the article is to determine the effect of antioxidants on the activity of xanthine oxidase in fresh ovine milk. Various natural and artificial antioxidants were examined for the detection of xanthine oxidase (XO) activity in ovine milk. Among the natural antioxidants, L-cysteine was more effective in the stabilization of XO in heated milk. XO of sheep milk activated by heat treatment in the presence of cysteine and molybdenum became able to convert nitrate and nitrite to nitric oxide (NO). Therefore, L-cysteine was used for double purposes: as the protector of enzyme active center against the oxidation during heat treatment of milk and as a reagent for S-nitrosothiol formation. Hypoxanthine, as a natural substrate of XO, is an effective electron donor for nitrate reductase (NR) and nitrite reductase (NiR) activities. Heat treatment of the milk in the presence of exogenous lecithin increased the activity of NR and NiR of XO and CysNO formation. Thus, during the heat treatment: a) excess of exogenous phospholipids disintegrates the structure of milk fat globule membrane (MFGM) and b) enzyme molecules denatured partially and their active center became available for exogenous cysteine, molybdenum, hypoxanthine, and nitrate or nitrite.

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