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Changes in the Content of Dietary Fiber, Flavonoids, and Phenolic Acids in the Morphological Parts of Fagopyrum tataricum (L.) Gaertn Under Drought Stress
Background: Tartary buckwheat is a plant recognized for its resistance to various environmental stresses. Due to its valuable source of phenolic compounds, Fagopyrum tataricum is also characterized as a medicinal plant; therefore, the aim of this study was to investigate the drought stress for the levels of phenolic compounds in the morphological parts of the plant. Methods: This experiment was conducted in 7 L pots under laboratory conditions. Phenolic compounds were identified using a UHPLC–MS chromatography system. Antioxidant activity was assessed using well-known methods, including the DPPH scavenging activity and ferrous ion chelating activity. Results: In Tartary buckwheat leaves, stems, seeds, and husks, 57 phenolic compounds were identified, with a predominance of quercetin 3-rutinoside, quercetin, kaempferol-3-rutinoside, kaempferol, and derivatives of coumaric acid. It was observed that the Tartary buckwheat samples subjected to drought stress exhibited a slight decrease in the majority of individual phenolic compounds. Conclusions: The measurement of biological parameters indicated that plant regeneration after drought stress demonstrated a rapid recovery, which can be a positive response to the progression of climate changes.
Phytostimulator Application after Cold Stress for Better Maize (Zea mays L.) Plant Recovery
Phytostimulators are attracting considerable attention for replacing mineral fertilizers, which are of environmental concern, being especially forbidden in organic farming. The benefit of applying such products based on microorganisms (e.g., algae extract) or minerals of nano-meter-sized particle (e.g., nanofertilizers) is that plants can uptake them faster than soil fertilizers, targeting plant growth by regulating their phytohormones, as well as improving plant tolerance to unfavorable environmental conditions (e.g., cold stress). The aim of this study was to test and evaluate the effects of three commercial phytostimulators, called biostimulants (a seaweed-based extract—Kelpak®, mineral nanoparticles—Nano Active®, zinc nanoparticles—Dynamic Cresco®) on yield, chlorophyll content, level of CO2 assimilation and the effectiveness of PSII under cold stress. The values of all chlorophyll fluorescence and photosynthetic parameters significantly decreased under cold, which indicated a strong inhibition of light-phase photosynthesis in maize leaves. Predicted by the regression analysis minimum, 20 days was enough for maize plants to recover from the inhibition caused by stress damages in their photosynthetic apparatus. At the final measurement in maize growth stage BBCH 65, all the tested phytostimulators showed significant effects in increased values of effective quantum yield of photosystem II, maximum photosynthetic efficiency of PSII and electron transport rate. At this stage, Dynamic Cresco® and Nano Active® treatment significantly increased the value of maximum net photosynthetic rate (15.37% and 18.85%, respectively) and leaf chlorophyll content (7.8% and 8.7%, respectively). The application of Dynamic Cresco® significantly promoted total dry weight by 43.4% in comparison to control under stress growth conditions with cold. These phytostimulators can be used to enhance yield and physiological status of plants after abiotic stress (such as cold) to improve crop productivity, especially in organic farming.