Climate changes, which result in the occurrence of periods with relatively high temperatures during the winter, can lead to the deacclimation of cold-hardened plants and cause problems with their winter survival. The aim of these studies was to investigate the physiological changes (photosynthesis and water relations including aquaporin expression) that accompany deacclimation process in the economically important winter oilseed rape plants. The effect of deacclimation on frost tolerance was also estimated for two tested cultivars: semi-dwarf and plants of a normal height. After cold acclimation at 4 °C (compared to the unacclimated control) the typical changes that accompany cold acclimation such as an increase in the content of water-soluble sugars or a lower water content in the leaves, which lead to an increased frost tolerance, were observed. Deacclimation partially or completely reversed these changes, which resulted in a decreased frost tolerance that was accompanied by a decrease in the content of sugars and an increase of the osmotic potential. The chemical composition of the leaves, which was measured using FT-Raman spectroscopy also clearly confirmed the metabolic differences between the cold-acclimated and deacclimated plants. The plants were significantly different in regard to the content of the various pigments as well as fatty acids and polysaccharides. The phenomenon of a deacclimation-induced decrease in aquaporin PIP1 accumulation, which was accompanied by unchanged PIP1 transcript accumulation, will be discussed in the aspects of the water relations and decreased frost tolerance in deacclimated plants.

Omitting the far‐red in LED lighting for bioreactors is inexplicable because it affects photosynthetic efficiency and photomorphogenetic activity. Therefore, this work compares three light sources (fluorescent—white light (WL), and LED: blue + red—BRL and blue + red + far‐red—BRFRL) for cultures of Chlorella vulgaris. Metabolic activity was determined by isothermal calorimetry. Changes in the chemical composition of biomass were examined by spectrofluorimetry and Raman spectroscopy. Maximum quantum yield of photosystem II was determined on the basis of chlorophyll a fluorescence parameters. The algae grown under BRL produced significantly more thermal energy than those cultured under BRFRL and WL. The Raman spectra of cultures showed characteristic bands for carotenoids, chlorophyll, phenolics, lipids, aliphatic carbohydrates, pectins, and disaccharides. According to the cluster analysis, the chemical composition of cultures grown under BRL and BRFRL was very similar, whereas the WL represented a distinct group. BRL and BRFRL stimulated the biosynthesis of an unidentified compound(s) with fluorescence maximum at 614 nm. At the beginning of the cultivation, photosystem II had very weak photochemical activity. Under BRFRL, ratios of Fv/Fm reached the maximum after 4 days, whereas under BRL and WL, after 6 days of cultivation. The results point to the favorable influence of the far‐red on the metabolism of microalgae.

imaging technique. PMMoV inoculation also led to a significant rise of ion leakage and heat emission, to the up-regulation of the pepper CCD gene as well as to decreased PSII efficiency, but these responses were much weaker than in the case of ObPV inoculation. Chlorophyll b and total carotenoid contents as measured by spectrophotometric methods were not significantly influenced by any virus inoculations when these pigment contents were calculated on leaf surface basis. On the other hand, near-infrared FTRaman spectroscopy showed an increase of carotenoid content in ObPV-inoculated leaves suggesting that the two techniques detect different sets of compounds.

Tribenuron-methyl is the active substance of the herbicide used for weed control in crops. The aim of this study was to investigate differences in the metabolic response of seeds, seedlings and leaves of Centaurea cyanus L., depending on the degree of resistance to tribenuron-methyl. Changes in the values of selected biochemical and physiological parameters (germination index, chemical composition, photochemical efficiency of photosystem II and the emission spectra of blue-green fluorescence) presented herein make it possible to determine the differences between cornflower biotypes with various types of resistance to the tested herbicide. Moreover, differences in the chemical composition of dry seeds between biotypes susceptible and resistant to tribenuron-methyl were observed before using the herbicide. The degree of resistance to the herbicide-resistant or susceptible, but not the types of this resistance-mutational or metabolic, can be distinguished on the basis of the presented parameters. These findings allow for early diagnosis of the resistance of cornflower to tribenuron-methyl. Additionally, we suggest that the described parameters might be used as physiochemical markers for early estimation of weed resistance to various types of herbicide. The presented conclusions are especially important for agricultural practice.

Research ArticleFar-red light (720 or 740 nm) improves growth and changes the chemical composition of Chlorella vulgaris Far-red (FR) light is crucial for the efficiency of photosynthesis and photomorphogenetic activity. This study investigated whether FR light at different wavelengths affects the Chlorella vulgaris biomass growth rate and chemical composition. For this purpose, FR was added to the blue-red (R) light at the wavelength of 720 nm (BRFR 720 L [blue + R + FR 720 nm light]) or 740 nm (BRFR 740 L [blue + R + FR 740 nm light]). BRFR 740 L allowed both higher growth rate and increased amount of total biomass compared to BRFR 720 L (blue + R + FR 720 nm light). The chemical composition of C. vulgaris biomass, analyzed by FT-Raman spectroscopy on lyophilized cells, significantly correlated with the applied FR component. The differences in lipid, carotenoid, and chlorophyll contents were particularly evident and all were higher in BRFR 740 L. Fluorescence emissions spectra of C. vulgaris cells were measured in the range 420-800 nm in the cuvette equipped with a magnetic stirrer preventing sedimentation of the cells during measurement. In the blue-green range (420-650 nm) fluorescence emission spectra indicated that changes in the chemical composition of phenolic compounds in the algae depended on the wavelength of FR used in LED matrices. This work showed that the use of FR of a wavelength 740 nm in the bioreactor's light source significantly improves biomass production of C. vulgaris cultures. IntroductionThe light, among the many factors influencing the growth and metabolism of the algae, is one of the most important but also most highly variable parameter. It has been shown that the spectral composition of light that exerts a positive influence on the growth of a particular strain of algae is not necessarily beneficial for growth of another strain [1]. Hence the importance of the selection of spectral composition of light. Both higher and lower plants have developed many photoreceptors to estimate the intensity of the wavelength and the direcCorrespondence: Prof. Andrzej Skoczowski (amskoczowski@gmail .com), Institute of Biology, Pedagogical University of Cracow, ul. Podchorążych 2, PL 30-084 Cracow, Poland.Abbreviations: BR, blue + red light; Chl, chlorophyll; F450, blue fluorescence; F530, green fluorescence; F690, red chlorophyll fluorescence; F735, far-red chlorophyll fluorescence; F450/F530, ratio of the blue to green fluorescence; F450/F690, fluorescence ratio blue/red; F450/F735, fluorescence ratio blue/far-red; F690/F735, chlorophyll fluorescence ratio red/far-red; FR, far-red; R, red light; WL, white light tion of the light [2,3]. Red (R) and blue light plays an important role in the photosynthesis and photomorphogenesis, thus influencing the development and metabolism of autotrophic plants. The essential light requirement of the photosynthesis process is the PAR (photosynthetically active radiation) range, that is from 400 to 700 nm (the end of absorption spectrum of the chlorophyll [Chl]). H...

Bio-based nanoemulsions are part of green pest management for sustainable agriculture. This study assessed the physicochemical properties and the herbicidal activities of the peppermint essential oil nanoemulsions (PNs) in concentrations 1.0–10% stabilized by Eco-Polysorbate 80 on germinating seeds and young plants of maize and barnyard grass. Based on the design of experiment (DOE) results, the final nanoemulsion formulations were obtained with 1, 1.5, 2, and 5% of essential oil concentration. Biological analyses were conducted to select the most promising sample for selective control of barnyard grass in maize. Seedlings growing in the presence of PNs displayed an overall inhibition of metabolism, as expressed by the calorimetric analyses, which could result from significant differences in both content and composition of carbohydrates. Concentration–response sub estimation showed that leaf-sprayed concentration of PN causing 10% of maize damage is equal to 2.2%, whereas doses causing 50% and 90% of barnyard grass damage are 1.1% and 1.7%, respectively. Plants sprayed with PN at 5% or 10% concentration caused significant drops in relative water content in leaves and Chlorophyll a fluorescence 72 h after spraying. In summary, peppermint nanoemulsion with Eco-Polysorbate 80 at 2% concentration is a perspective preparation for selective control of barnyard grass in maize. It should be analyzed further in controlled and field conditions.

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We have investigated the influence of mechanical wounding of Arabidopsis rosette leaves on photochemical activity of photosystem II, gas exchange, sugar content and sucrose metabolism in wild-type plants and mutants impaired in hormonal balance. The aos (jasmonate deficiency), rcd1 (reduced sensitivity to ABA, ethylene, and methyl-jasmonate), and ein4 (ethylene insensitivity) mutants have been used. Generally, mechanical injury led to dynamic changes in metabolism, especially in sugar and carotenoid contents. Whereas all mutants showed lower photosynthesis and respiration in comparison to the wildtype plants, leaf wounding caused a decrease in respiration in aos and ein4, and an increase in respiration in wild type. The mechanical injury triggered an increase of the activities of sucrose hydrolysing enzymes, such as sucrose synthase (SuSy) and several types of invertases, which was most evident in case of rcd1 and aos plants. This was correlated with injury-related changes in soluble sugars in the mutants, but not in wild-type plants where sugar content was not significantly affected by wounding. The results confirm the key role of stress hormones, such as jasmonate and ethylene, in mediating stress responses after wounding. The outcome of the experiments also underlines important roles of SuSy and invertase in regeneration of injured tissues, most probably by providing precursors for cell wall biosynthesis and by modulating sugar-signalling in plant cells. Keywords Carbohydrates Á Chlorophyll a fluorescence Á FT-Raman spectroscopy Á Invertase Á Jasmonate-deficient mutant Á Sucrose synthase Abbreviations Aos JA deficient mutant CIN Neutral invertase cwINV Cell wall associated invertase ein4 Ethylene insensitive mutant Fv/Fm Photochemical efficiency of PSII JA Jasmonic acid NPQ Nonphotochemical quenching qP Quenching in steady-state QY Steady-state quantum yield rcd1-1 Radical-induced cell death 1 mutant with reduced sensitivity to ABA, ethylene, and methyl jasmonate ROS Reactive oxygen species SuSy Sucrose synthase VIN Vacuolar invertase W 2 2 h after wounding W 24 24 h after wounding Wt Wild type plants