The wheat plants were pretreated with the selective herbicide Serrate^® (Syngenta) and subsequently subjected to drought or flooding stress for 7 days. The gas exchange parameters, chlorophyll a fluorescence and leaf pigment content were measured. The measurements were performed during the stress period and after 4 days of plants recovery. Herbicide pretreatment did not cause significant alterations in photosynthesis and fluorescence parameters in alone- or combined-treated seedlings. A significant reduction in gas exchange parameters (net photosynthesis rate, stomatal conductance, transpiration rate, and water use efficiency), F_v/F_m and F_v/F₀ values during drought or flooding was observed. The disruption of photosynthesis together with reduction in the pigment content was stronger in droughted than flooded plants. When the normal irrigation was restored, the gas exchange and fluorescence parameters tended to increase. The comparative analysis of recovery and resilience indices of photosynthetic traits indicate that the plants subjected to drought recovered better than those subjected to flooding stress.

Drought stress affects many aspects of plant biochemistry, with photosynthesis being one the most significantly impaired physiological processes. Melatonin is a natural antioxidant with growth-regulating properties in plants. Its diverse physiological functions have been extensively studied in recent decades. Changes in leaf gas exchange and chlorophyll a fluorescence parameters were investigated in young wheat plants (Triticum aestivum L.) cv. Fermer and cv. Gines which were characterized to differ in their responses to drought, with cv. Gines being more tolerant than cv. Fermer. The plants were subjected to drought for five days by withholding their water supply. Melatonin was applied as a root supplement to the irrigation water before or after the drought period. Analyses were performed before and at the end of the stress period, as well as during the recovery phase. Changes in leaf pigment content, photosynthetic rate, stomatal conductance, and transpiration, as well as some chlorophyll a fluorescence parameters, were recorded. Melatonin alone did not cause considerable changes in the measured traits. We found a significant decrease in leaf gas exchange parameters, Fv/Fm and Fv/F0 values, and leaf pigments due to drought, especially in cv. Fermer. The data show that the application of melatonin favorably influenced the efficiency of the photosynthetic apparatus under water deprivation and during plant recovery. The pre-treatment with melatonin maintained the photosynthesis-related parameters closer to the control levels during the stress period. Both melatonin treatments supported the recovery of photosynthesis when the water supply was restored and the post-drought treatment showed a similar but weaker effect than pre-drought treatment.

Ludisia discolor is commonly known as a jewel orchid due to its variegated leaves. Easy maintenance of the orchid allows it to be used as a test system for various fertilizers and nutrient sources, including aquaponic water (AW). First, we applied DNA barcoding to assess the taxonomic identity of this terrestrial orchid and to construct phylogenetic trees. Next, the vegetative organs (leaf, stem, and root) were compared in terms of the level of metabolites (reducing sugars, proteins, anthocyanins, plastid pigments, phenolics, and antioxidant activity) and nutrient elements (carbon, nitrogen, sodium, and potassium), which highlighted the leaves as most functionally active organ. Subsequently, AW was used as a natural source of fish-derived nutrients, and the orchid growth was tested in hydroponics, in irrigated soil, and in an aquaponic system. Plant physiological status was evaluated by analyzing leaf anatomy and measuring chlorophyll content and chlorophyll fluorescence parameters. These results provided evidence of the beneficial effects of AW on the jewel orchid, including increased leaf formation, enhanced chlorophyll content and photosystems’ productivity, and stimulated and prolonged flowering. The information acquired in the present study could be used in addressing additional aspects of the growth and development of the jewel orchid, which is also known for its medicinal value.

Owing to global climate changes, periods of soil drought or waterlogging occur. Each of these factors causes negative effects on plant physiological processes and growth. Weeds are another factor that limits plant productivity. The main task of this study is to investigate the physiological reactions of triticale to herbicide treatment and subsequent drought or waterlogging. Young triticale plants were treated with Serrate^® (selective herbicide produced by Syngenta) and exposed for 7 days to drought or waterlogging. Plant growth, chlorophyll and carotenoids content, the net photosynthesis rate and chlorophyll a fluorescence were measured during the stress period and after 4 days of plant recovery. Herbicide by itself did not induce considerable changes in the abovementioned parameters during the stress period. Serrate^® did not affect strongly the efficiency of the photosynthetic machinery under harsh conditions. A significant reduction in fresh weight (85%), water content (93%), net photosynthesis rate, chlorophyll a fluorescence indices F_v/F_m and F_v/F₀, and leaf pigments (58% for chlorophyll a, 53% for chlorophyll b, and 45% for carotenoids) was found because of drought. Waterlogging also influenced negatively these parameters but to a smaller extent. After resuming the normal irrigation, the photosynthesis and chlorophyll a fluorescence tended to increase and showed signs of recovery. The comparative analysis of growth and photosynthetic parameters demonstrated that triticale plants subjected to waterlogging could recover to a higher degree than those exposed to drought.

Photosynthetica covers wide range of photosynthesis research or research including photosynthetic parameters of both experimental and theoretical nature.