Determination of chlorophyll content as an indirect method of estimating the productivity of vegetation represents a good way to gain an understanding of the photosynthetic regime of plants. Physiological investigations of chlorophyll and carotenoid content in the uppermost internode of several wheat cultivars were carried out at the outset of the flowering phase. The dependence of chlorophyll and carotenoid content on the fertilization variant was established at that time. The tested wheat cultivars were grown under conditions of five fertilization variants. The content of chlorophyll a, chlorophyll b, and total chlorophyll (Chl a+b) was measured and carotenoid content was determined on each variant. The results indicate that chlorophyll and carotenoid content depended on the presence and ratio of mineral elements in the substrate. This is demonstrated by the variant with unfertilized soil, where chlorophyll and carotenoid content in all cultivars was lowest. The variant of fertilization with N and P turned out to be most favorable. The next most favorable variant was the one with nitrogen alone, and it was followed by the variant with N and K.

Many compounds from the phenolic group, flavonoids in particular, are well-known antioxidants, although their role in plant response to stress is debatable. The aim of this study was to determine the variability of the phenolic content and the antioxidant activity of Olea europaea leaf samples from different habitats. The determination included measurement of the total quantity of phenolics, the flavonoid content, as well as the antioxidant activity of the two types of methanolic leaf extracts of O. europaea from several natural habitats in the Mediterranean region (Tunisia, Malta and Montenegro) and from cultivated conditions (France and Serbia). The results showed that both the total quantity of phenols and flavonoids as well as the intensity of antioxidant activity in the two types of extracts largely depended on the type of habitat. The total quantity of phenols and flavonoids was greater in the samples from cultivated plants which demonstrated the significance of certain conditions in terms of the correlation between the intensity of primary and secondary metabolism. However, the values of antioxidant activity in both types of extract were higher in the samples from natural habitats. The results showed that plants from natural habitats contain secondary metabolites with high biological activity. It could be speculated that these active substances play an important role in the adaptation of plants to the stress caused by arid conditions.

Chilling stress in spring and mid-season heat stress are important environmental stresses that can significantly affect plant productivity. The objectives of this study were to understand the effects of cold (4 and 10 °C) or heat (30 and 40 °C) stress on biochemical and physiological traits in leaves and roots of basil (Ocimum basilicum L. cv. ‘Genovese’) young plants. After short-time exposure to mild and severe temperature stresses, both photosynthetic pigments’ and protein, as well as enzymatic and non-enzymatic defense components in basil leaves and roots, were quantified and compared with the control non-stressed plants. It was shown that both cold and heat treatment increase the content of chlorophyll a, chlorophyll b, and carotenoids. Chilling correlated with higher content of soluble proteins in leaves, whereas the concentration of these osmoprotectants in roots was higher under both cold and heat stress. For all tested antioxidant enzymes, higher activity was measured in leaves, and activity was related to temperature stress. SOD, CAT, A-POX, and P-POX activities was induced under heat stress, while the higher activity of SOD, CAT, P-POX, and G-POX was recorded under cold stress, compared to the control. In addition to the induced activity of enzymatic components, the content of secondary metabolites including total phenolics, flavonoids, and total anthocyanins, was several times higher compared to the non-stressed plants. Furthermore, total phenolic content was higher in roots than in leaves. Significant positive correlation can be seen among photosynthetic pigments, SOD, total phenolics, and flavonoids under severe temperature stress (4 or 40 °C) in basil leaves, while for roots, positive correlation was found in the content of secondary metabolites and activity of CAT or peroxidases. Obtained results are discussed in terms of phenotyping of O. basilicum cv. ‘Genovese’ response to heat and chilling stress, which should contribute to a better understanding of merged responses to cold and heat tolerance of this valuable crop.

Radish (Raphanus sativus L.) is a vegetable cultivated worldwide because of its large succulent hypocotyls. The priming method initiates metabolic processes at early stages and regulates the metabolic events in seed necessary for germination. This research was conducted to examine the influence of various priming treatments on physiological performance (germination, growth, lipid peroxidation, primary and secondary metabolism) and antioxidant activity of radish seedlings. On the basis of germination and growth characteristics, vigor index, and relative water content in leaves, it was confirmed that priming treatments with 0.01% ascorbic acid (AA) and 1% KNO₃ improves the initial stages of radish development. Furthermore, the efficiency of AA as a priming agent was confirmed through the reduction of malondialdehyde (MDA) level compared to unprimed seedlings. On the other hand, hormopriming with indole-3-acetic acid (IAA) significantly increased the concentration of photosynthetic pigments and total soluble leaf proteins compared to non-primed seedlings. The highest content of total phenolic compounds, including flavonoids, were obtained after hormopriming with 1 mM IAA and halopriming with 1% MgSO₄. On the basis of the percentage of inhibition of DPPH radicals, it was confirmed that treatments with IAA and AA can improve the antioxidant activity of radish seedlings. This study provides useful information regarding the possibilities of pregerminative metabolic modulation through the seed priming for the biochemical and physiological improvement of radish, and this topic should be further investigated in order to determine the potential use of AA and IAA as suitable priming agents in radish commercial production.