Supplemental ultraviolet-B Radiation Research Articles

Supplementary UV-B Radiation Effects on Photosynthetic Characteristics and Important Secondary Metabolites in Eucommia ulmoides Leaves.

To explore the effects of ultraviolet light supplementation on the photosynthetic characteristics and content of secondary metabolites in the leaves of Eucommia ulmoides Oliver (E. ulmoides), the effects of supplementary UV-B (sUV-B) radiation on the medicinally active components of E. ulmoides were comprehensively evaluated. In our study, we selected leaves of five-year-old E. ulmoides seedlings as experimental materials and studied the effect of supplemental ultraviolet-B (sUV-B) radiation on growth, photosynthetic parameters, photosynthetic pigments, fluorescence parameters, and secondary metabolites of E. ulmoides using multivariate analysis. The results showed that the leaf area and the number of branches increased after sUV-B radiation, which indicated that sUV-B radiation was beneficial to the growth of E. ulmoides. The contents of chlorophyll a and chlorophyll b increased by 2.25% and 4.25%, respectively; the net photosynthetic rate increased by 5.17%; the transpiration rate decreased by 35.32%; the actual photosynthetic efficiency increased by 10.64%; the content of the secondary metabolite genipin increased by 12.9%; and the content of chlorogenic acid increased by 75.03%. To identify the genes that may be related to the effects of sUV-B radiation on the growth and development of E. ulmoides leaves and important secondary metabolites, six cDNA libraries were prepared from natural sunlight radiation and sUV-B radiation in E. ulmoides leaves. Comparative analysis of both transcriptome databases revealed a total of 3698 differential expression genes (DEGs), including 1826 up-regulated and 1872 down-regulated genes. According to the KOG database, the up-regulated unigenes were mainly involved in signal transduction mechanisms [T] and cell wall/membrane biogenesis [M]. It is also involved in plant hormone signal transduction and phenylpropanoid biosynthesis metabolic pathways by the KEGG pathway, which might further affect the physiological indices and the content of chlorogenic acid, a secondary metabolite of E. ulmoides. Furthermore, 10 candidate unigenes were randomly selected to examine gene expression using qRT-PCR, and the six libraries exhibited differential expression and were identical to those obtained by sequencing. Thus, the data in this study were helpful in clarifying the reasons for leaf growth after sUV-B radiation. And it was beneficial to improve the active components and utilization rate of E. ulmoides after sUV-B radiation.

Enhanced ultraviolet-B radiation reduces methane emission in one of the oldest and largest rice terraces in China but triggers new challenges

Ultraviolet-B (UV-B) radiation enhancement and climate warming are two critical environmental issues worldwide. Understanding the effects of enhanced UV-B radiation on methane (CH4) emission and rice growth in paddy fields are fundamental for human sustainability. In situ field experiments with ambient and supplemental UV-B radiation stresses were conducted in paddy fields subjected to prolonged flooding at Yuanyang Terraces, Southwest China. Annual dynamics and driving factors of CH4 emission were investigated; the effects of enhanced UV-B radiation on soil carbon conversion, enzyme activities and rice growth were studied. Yuanyang Terrace’s CH4 emission levels were 1.6 and 3.3 times higher than China’s and global mean values, respectively. Weather conditions (27.02%) and the stage of rice cultivation (25.65%) were the predominant factors in driving CH4 emission. During the winter fallow period, enhanced UV-B principally affected rice straw and its decomposition, subsequently changing both soil enzyme activities and labile organic carbon levels to reduce CH4 emission. On the other hand, during the rice-growing period, enhanced UV-B affected rice growth, subsequently changing rhizospheric microorganism and soil enzyme activities to reduce CH4 emission. Meanwhile, enhanced UV-B could affect the growing of rice to further change the balance between CH4 and CO2 in the rhizosphere, and the corresponding trade-off could reduce the shifts in global warming potential of rice terraces. In total, enhanced UV-B reduced CH4 emission in the rice terraces by 15.70%, but would increase CO2 and N2O emissions, and negatively affect paddy yields, thus hindering regional food security and sustainable development. Therefore, integrating a consideration of the mitigation of greenhouse gas emissions with a concern for food security is a prospect for future research.

Static magnetic field treatment enhanced photosynthetic performance in soybean under supplemental ultraviolet-B radiation.

The study was performed to analyze the impact of seed pretreatment by static magnetic field (SMF) of 200 mT for 1h on photosynthetic performance of soybean (Glycine max) seedlings under ambient (aUV-B) and supplemental ultraviolet-B (a+sUV-B) stress. Ambient and supplemental UV-B were found to decrease the plant growth, chlorophyll concentration, PSII efficiency, selected JIP-test parameters such as Fv/Fm, φEo, ΔV(I-P), PIABS, PItotal, and rate of photosynthesis in the leaves of soybean seedlings emerged from untreated (UT) seeds. aUV-B and a+sUV-B were observed to increase the synthesis of UV-B-absorbing substances (UAS), reactive oxygen species (ROS) like superoxide radical (O2·-) and hydrogen peroxide (H2O2), antioxidants like ascorbic acid and α-tocopherol and decrease the nitrate reductase (NR) activity; subsequently, it results in a decreased rate of photosynthesis, biomass accumulation, and yield. However, our results provided evidence that SMF pretreatment increased the tolerance of soybean seedlings to UV-B radiation by increased NO content and NR activity; higher efficiency of PSII, higher values of φEo, ΔV(I-P), PIABS, and PItotal, decreased intercellular CO2 concentration, lower amount ofUAS, ROS, and antioxidants that consequently improve the yield of soybean plants under aUV-B as well as a+sUV-B stress. Thus, our results suggested that SMF pretreatment mitigates the adverse effects of UV-B stress by the enhancement in photosynthetic performance along with higher NO content which may be able to protect the plants from the deleterious effects of oxidative stress caused by UV-B irradiation.

Transgenic rice Oryza glaberrima with higher CPD photolyase activity alleviates UVB-caused growth inhibition

ABSTRACT The ultraviolet B (UVB) sensitivity of rice cultivated in Asia and Africa varies greatly, with African rice cultivars (Oryza glaberrima Steud. and O. barthii A. Chev.) being more sensitive to UVB because of their low cyclobutane pyrimidine dimer (CPD) photolyase activity, which is a CPD repair enzyme, relative to Asian rice cultivars (O. sativa L.). Hence, the production of UVB-resistant African rice with augmented CPD photolyase activity is of great importance, although difficulty in transforming the African rice cultivars to this end has been reported. Here, we successfully produced overexpressing transgenic African rice with higher CPD photolyase activity by modifying media conditions for callus induction and regeneration using the parental line (PL), UVB-sensitive African rice TOG12380 (O. glaberrima). The overexpressing transgenic African rice carried a single copy of the CPD photolyase enzyme, with a 4.4-fold higher level of CPD photolyase transcripts and 2.6-fold higher activity than its PL counterpart. When the plants were grown for 21 days in a growth chamber under visible radiation or with supplementary various UVB radiation, the overexpressing transgenic plants have a significantly increased UVB resistance index compared to PL plants. These results strongly suggest that CPD photolyase remains an essential factor for tolerating UVB radiation stress in African rice. As a result, African rice cultivars with overexpressed CPD photolyase may survive better in tropical areas more prone to UVB radiation stress, including Africa. Collectively, our results provide strong evidence that CPD photolyase is a useful biotechnological tool for reducing UVB-induced growth inhibition in African rice crops of O. glaberrima.

UV-B Radiation Largely Promoted the Transformation of Primary Metabolites to Phenols in Astragalus mongholicus Seedlings.

Ultraviolet-B (UV-B) radiation (280–320 nm) may induce photobiological stress in plants, activate the plant defense system, and induce changes of metabolites. In our previous work, we found that between the two Astragalus varieties prescribed by the Chinese Pharmacopoeia, Astragalus mongholicus has better tolerance to UV-B. Thus, it is necessary to study the metabolic strategy of Astragalus under UV-B radiation further. In the present study, we used untargeted gas chromatography-mass spectrometry (GC-MS) and targeted liquid chromatography-mass spectrometry (LC-MS techniques) to investigate the profiles of primary and secondary metabolic. The profiles revealed the metabolic response of Astragalus to UV-B radiation. We then used real-time polymerase chain reaction (RT-PCR) to obtain the transcription level of relevant genes under UV-B radiation (UV-B supplemented in the field, λmax = 313 nm, 30 W, lamp-leaf distance = 60 cm, 40 min·day−1), which annotated the responsive mechanism of phenolic metabolism in roots. Our results indicated that supplemental UV-B radiation induced a stronger shift from carbon assimilation to carbon accumulation. The flux through the phenylpropanoids pathway increased due to the mobilization of carbon reserves. The response of metabolism was observed to be significantly tissue-specific upon the UV-B radiation treatment. Among phenolic compounds, C6C1 carbon compounds (phenolic acids in leaves) and C6C3C6 carbon compounds (flavones in leaves and isoflavones in roots) increased at the expense of C6C3 carbon compounds. Verification experiments show that the response of phenolics in roots to UV-B is activated by upregulation of relevant genes rather than phenylalanine. Overall, this study reveals the tissues-specific alteration and mechanism of primary and secondary metabolic strategy in response to UV-B radiation.

Impact of Light Stress on Plant Based Medicinally Active Compounds

Light has several positive and negative impacts on plant growth and physiological processes. Medicinal plants contribute significantly higher proportions of world plant flora and are natural source of rich medicinal compounds. Sufficient literature is available on plant responses to light stress but studies on medicinal plants are limited. This review discusses how different light conditions affect production of plant-based medicinal compounds which are broadly secondary products formed during adverse environmental conditions to cope up the stress. Here, some medicinal plants are reviewed which were exposed to different light conditions including blue light, red light, yellow light, green light, far red light, wavelength specific light treatments, pulsed pre light, specific light intensity, light shade treatments, and supplemental ultraviolet-B radiation. Secondary metabolites considered for the review are anthocyanin, flavonoids, alkaloids, essential oils, cannabinoids and glucosinolates. Most of the results revealed increase in content of medicinal compounds under differentially exposed light conditions with maximum effect under sUV-B exposure. Advancement in the knowledge of medicinal plants response to light stress can help in understanding the mechanism of medicinal compound formation and their regulation which can be further utilized in the production of medicinally active compounds.

EVALUATING THE CLINICAL AND PHYSIOLOGICAL EFFECTS OF LONG-TERM ULTRAVIOLET B RADIATION ON RABBITS (ORYCTOLAGUS CUNICULUS)

Vitamin D is an essential hormone in vertebrates. Most animals acquire this hormone through their diet and/or exposure to ultraviolet B (UVB) radiation. The objectives for this research were to evaluate the clinical and physiologic effects of artificial UVB light supplementation on rabbits (Oryctolagus cuniculus) and to evaluate the long-term safety of artificial UVB light supplementation over a 6-month period. Twelve New Zealand white rabbits were randomly assigned to one of two treatment groups: Group A was exposed to 12 hours of artificial UVB radiation daily and Group B received ambient fluorescent light with no UVB supplementation for 12 hours daily. All animals were offered the same diet and housed under the same conditions. Blood samples were collected every 3 weeks over 6 months to measure blood chemistry values, parathyroid hormone, ionized calcium, and serum 25-hydroxyvitamin D3 (25-OHD3) levels. Serial ophthalmologic examinations were performed at the beginning of the study and every 2 months thereafter. At the end of the study the animals were euthanized and necropsied. Mean ± SD serum 25-OHD3 concentrations differed significantly (P = 0.003) between animals provided supplemental UVB radiation (83.12 ± 22.44 nmol/L) and those not provided UVB radiation (39.33 ± 26.07 nmol/L). There were no apparent negative clinical or pathologic side effects noted between the groups. This study found that exposing rabbits to UVB radiation long term significantly increased their circulating serum 25-OHD3 levels, which was sustainable over time.

Interactive effects of supplemental ultraviolet-B radiation and indole-3-acetic acid on Coleus forskohlii Briq.: Alterations in morphological-, physiological-, and biochemical characteristics and essential oil content

Ultraviolet (UV)-B radiation and the growth hormone indole-3-acetic acid (IAA) have been known to cause various changes in plants at morphological and physiological levels as individual entities, but their interactive effects on the overall plant performance remain practically unknown. The present study was conducted under near-natural field conditions to evaluate the effects of supplemental (s)-UV-B (ambient+3.6kJm−2day−1) treatment alone, and in combination with two doses of IAA (200ppm and 400ppm) exogenously applied as foliar spray on various growth-, morphological-, physiological-, and biochemical parameters of an indigenous medicinal plant, Coleus forskohlii. Under s-UV-B, the plant growth and morphology were adversely affected (along with reductions in protein- and chlorophyll contents) with concomitant increase in secondary metabolites (as substantiated by an increase in the activities of various enzymes of the phenylpropanoid pathway) and cumulative antioxidative potential (CAP), suggesting the plant's capability of adaptive resilience against UV-B. The essential oil content of the plant was, however, compromised reducing its pharmaceutical value. IAA application at both doses led to a reversal in the effects caused by s-UV-B radiation alone; both the plant growth as well as the essential oil content improved, especially at the higher IAA dose, suggesting its ameliorative role against UV-B induced oxidative stress, and also in improving the plant's medicinal value.

Anatomical Changes Linked Lerformance of Two Indigenous Medicinal Plants, Withania Somnifera Dunal and Coleus Forskohlii Briq. Exposed to Supplemental Ultraviolet-B Radiation

Anatomical Changes Linked Lerformance of Two Indigenous Medicinal Plants, Withania Somnifera Dunal and Coleus Forskohlii Briq. Exposed to Supplemental Ultraviolet-B Radiation

Effect of supplemental UV-B on yield, seed quality, oil content and fatty acid composition ofBrassica campestrisL. under natural field conditions

Thinning of stratospheric ozone layer had been reported since last fifty years due to emission of chlorofluorocarbons, resulting in an increase in ultraviolet-B (UV-B) radiation. The present study was conducted to examine the effects of supplemental UV-B (sUV-B) radiation (+7.2 kJ/m2/s) on yield and quality of seeds and oil of two cultivars of mustard, (Brassica campestris) L. cv. Sanjukta and Vardan. Number of pods, harvest index, test weight and oil content decreased due to sUV-B exposure in both cultivars. Seed quality was also reduced under sUV-B in terms of protein, sugar and amino acid contents. Further, quality of oil was deteriorated due to increases in erucic acid, polyunsaturated fatty acid and ω-6 fatty acid contents and reductions in oleic acid and nervonic acid contents due to sUV-B exposure. Cultivar Vardan showed more negative impact on seed yield due to UV-B stress, whereas quality of seed and oil was more affected in Sanjukta. Results of the present study confirmed the potential loss in y...

The role of supplemental ultraviolet-B radiation in altering the metabolite profile, essential oil content and composition, and free radical scavenging activities of Coleus forskohlii, an indigenous medicinal plant.

The effects of supplemental ultraviolet-B (s-UV-B; 3.6kJm(-2) day(-1) above ambient) radiation were investigated on plant metabolite profile, essential oil content and composition, and free radical scavenging capacities of methanolic extracts of Coleus forskohlii (an indigenous medicinal plant) grown under field conditions. Essential oil was isolated using hydrodistillation technique while alterations in metabolite profile and oil composition were determined via gas chromatography-mass spectroscopy (GC-MS). Leaf and root methanolic extracts were investigated via various in vitro assays for their DPPH radical-, superoxide radical-, hydrogen peroxide-, hydroxyl radical-, and nitric oxide radical scavenging activities, ferrous ion chelating activity, and reducing power. Phytochemical analysis revealed the presence of alkaloids, anthocyanins, coumarins, flavonoids, glycosides, phenols, saponins, steroids, tannins, and terpenoids. Oil content was found to be reduced (by ∼7%) in supplemental UV-B (s-UV-B) treated plants; the composition of the plant extracts as well as essential oil was also considerably altered. Methanolic extracts from treated plant organs showed more potency as free radical scavengers (their EC50 values being lower than their respective controls). Anomalies were observed in Fe(2+) chelating activity for both leaves and roots. The present study concludes that s-UV-B adversely affects oil content in C. forskohlii and also alters the composition and contents of metabolites in both plant extracts and oil. The results also denote that s-UV-B treated plant organs might be more effective in safeguarding against oxidative stress, though further studies are required to authenticate these findings.

Alterations in metabolite profile and free radical scavenging activities of Withania somnifera leaf and root extracts under supplemental ultraviolet-B radiation

The effects of supplemental ultraviolet-B (s-UV-B; 3.6 kJ m−2 day−1 above ambient) radiation on plant metabolite profile and free radical scavenging activities of Withania somnifera (an indigenous medicinal plant) under field conditions were investigated. The metabolite profiles of both leaves and roots were analyzed via GC–MS. The methanolic extracts were examined for their DPPH radical-, superoxide radical-, hydrogen peroxide-, hydroxyl radical-, and nitric oxide radical scavenging activities, ferrous ion chelating activity, and reducing power. GC–MS profile of leaves revealed increment in compounds such as isophytol (138.1 %), β-stigmasterol (183.05 %), trans-squalene (233.3 %), and Withaferin A (155.0 %), while compounds such as eugenol, β-carotene, lycopene, and vitamin E were detected in s-UV-B-treated leaves only. In roots, compounds such as ledol, neophytadiene, palmitic acid, retinol, sitosteryl oleate, and campesterol registered their presence only under s-UV-B. Methanolic extracts of treated plant organs were found to be more potent as free radical scavengers (their EC50 values being lower than those of control extracts). Anomalies were observed for nitric oxide radical scavenging in both leaves and roots. The present study indicates that s-UV-B alters the composition and contents of plant metabolites leading to an increase in their free radical scavenging activities. Hence, s-UV-B-treated plant organs might be more effective in combating oxidative stress as well as from a nutritional and health perspective.

Defence strategies adopted by the medicinal plant Coleus forskohlii against supplemental ultraviolet-B radiation: Augmentation of secondary metabolites and antioxidants

Supplementary ultraviolet-B (ambient+3.6 kJ m−2 day−1) induced changes on morphological, physiological, and biochemical characteristics (specifically the defence strategies: UV-B protective compounds and antioxidants) of Coleus forskohlii were investigated under field conditions at 30, 60, and 90 days after transplantation. Levels of secondary metabolites increased under s-UV-B stress; flavonoids and phenolics (primary UV-B screening agents) were recorded to be higher in leaves which are directly exposed to s-UV-B. This was also verified by enhanced activities of phenylpropanoid pathway enzymes: phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), 4-coumarate-CoA ligase (4CL), chalcone–flavanone isomerase (CHI), and dihydroflavonol reductase (DFR). Antioxidants, both enzymatic (ascorbate peroxidase, catalase, glutathione reductase, peroxidase, polyphenol oxidase, and superoxide dismutase) and non-enzymatic (ascorbic acid and α-tocopherol) also increased in the treated organs of the test plant, higher contents being recorded in roots except for ascorbic acid. On the contrary, protein and chlorophyll content (directly implicated in regulating plant growth and development) declined under s-UV-B. These alterations in plant biochemistry led the plant to compromise on its photosynthate allocation towards growth and biomass production as evidenced by a reduction in its height and biomass. The study concludes that s-UV-B is a potent stimulating factor in increasing the concentrations of defense compounds and antioxidants in C. forskohlii to optimize its performance under stress.

Ultraviolet-B radiation applied to detached peach fruit: A study of free radical generation by EPR spin trapping

In peaches, phenolic compounds are the major sources of antioxidants, and cyanidin-3-O-glucoside is the main anthocyanin present, above all in the skin. Anthocyanin content has been shown to increase after UV-B irradiation, which may be very harmful for all biological organisms due to the induction of the generation of reactive oxygen species (ROS). Peach fruits (cv. ‘Suncrest’) were exposed during post-harvest to supplemental ultraviolet-B radiation. A spin-trapping technique was used to monitor the generation of free radicals under UV-B, and 5-(diethoxy-phosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) was used as the spin trap. The flesh of peaches was essentially unaffected by the treatment, whereas the skin was responsive at the end of the treatment, accumulating ascorbate, flavonoids, cyanidin-3-O-glucoside, and showing a higher antioxidant activity. The levels of stable free radicals were also lower at the end of treatment. Carbon-centred radicals contributed the most to the total amounts of free radicals, whereas hydroxyl radicals and oxygen-centred free radicals contributed minimally. The carbon-centred free radical identified was the same as the one obtained after irradiation of authentic cyanidin-3-O-glucoside. During UV-B treatment cyanidin-3-O-glucoside increased and was capable of radicalization protecting the other organic molecules of the cell from oxidation. ROS, among which hydroxyl radicals, were thus maintained to minimal levels. This ability of cyanidin-3-O-glucoside displayed the mechanism underlined the tolerance to UV-B irradiation indicating that shelf life can be prolonged by the presence of anthocyanins. Thus, UV-B technique results a good approach to induce antioxidant production in peach fruits increasing their nutraceutical properties.

Responses of photosynthetic properties and antioxidant enzymes in high-yield rice flag leaves to supplemental UV-B radiation during senescence stage.

Despite the increasing occurrence of ultraviolet-B (UV-B) radiation, its molecular mechanism is poorly documented in higher plants compared to other environmental stress. In present study, the influence of supplemental UV-B radiation on photosynthetic performance and antioxidant enzymes in rice (Oryza sativa L.) was investigated. Supplemental UV-B radiation reduced net photosynthetic rate in rice flag leaves during senescence stage. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly inhibited by the increased thermal dissipation. Furthermore, 18 thylakoid membrane protein spots were differentially expressed (5-fold or greater variation compared to the control) in supplemental UV-B-treated rice. These identified proteins were involved in various cellular responses and metabolic processes including photosynthesis, stress defense, Calvin cycle, and others of unknown functions. Taken together, these results suggested that physiological changes that resulted from supplemental UV-B radiation were linked to the light reaction, carbon metabolism, and antioxidant enzymes in rice leaves during senescence stage.

Secondary metabolites and phenylpropanoid pathway enzymes as influenced under supplemental ultraviolet-B radiation in Withania somnifera Dunal, an indigenous medicinal plant

The present study aims to investigate the effects of supplemental ultraviolet B (3.6kJm−2day−1 above ambient) radiation on secondary metabolites and phenylpropanoid pathway enzymes of Withania somnifera under field conditions at 40, 70, and 100days after transplantation. Secondary metabolites’ (alkaloids, anthocyanins, carotenoids, flavonoids, lignin, phytosterols, saponins, and tannins) concentrations were analysed at the end of the treatments. Activities of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), 4-coumarate-CoA ligase (4CL), chalcone–flavanone isomerase (CHI), and dihydroflavonol reductase (DFR) were also determined. In treated plants, secondary metabolite-concentrations generally increased (higher concentrations being recorded in roots compared to leaves). Anomalies were recorded for lycopene in roots and phytosterols in leaves (all sampling ages); β-carotene declined in leaves at third sampling age. s-UV-B-treated plants depicted decrease in withanolide A content with concomitant increase in withaferin A (two major alkaloids analysed by HPLC) compared to their respective controls. Phenylpropanoid pathway enzyme-activities increased in leaves and roots under s-UV-B treatment, the latter showing greater increase. The study concludes that s-UV-B is a potent factor in increasing the concentrations of secondary metabolites and their biosynthetic pathway enzymes in W. somnifera.

Effects of Ultraviolet Radiation on Serum 25-Hydroxyvitamin D Concentrations in Captive Chinchillas (Chinchilla laniger)

Vitamin D is an important hormone in vertebrates, and most animals acquire this hormone through their diet and/or exposure to ultraviolet B (UVB) radiation. To date, no study has determined how chinchillas (Chinchilla laniger) acquire vitamin D. The objective of this study was to determine whether exposure to UVB radiation had an effect on serum 25-hydroxyvitamin D levels in captive chinchillas. Overall, 10 juvenile chinchillas were used for this scientific investigation. Baseline blood samples were collected from the animals while under isoflurane anesthesia to determine their serum 25-hydroxyvitamin D concentrations. The chinchillas were then randomly assigned to 2 treatment groups: Group A, 12 hours of UVB exposure per day and Group B, no UVB exposure. At the end of the study (Day 16), a second blood sample was collected from each animal while again under isoflurane anesthesia to measure serum 25-hydroxyvitamin D concentrations. Mean ± standard deviation serum 25-hydroxyvitamin D concentrations differed significantly (P = 0.048) between juvenile chinchillas provided supplemental UVB radiation (189.0 ± 102.7nmol/L) and those not provided supplemental UVB radiation (87.8 ± 34.4nmol/L). This study found that exposing juvenile chinchillas to UVB radiation significantly increased their circulating serum 25-hydroxyvitamin D levels. Because vitamin D is an essential hormone in vertebrates, these findings suggest that the provision of UVB radiation to captive chinchillas may be important. Further research to elucidate the importance of 25-hydroxyvitamin D and UVB radiation in captive chinchillas is required.

Impact of ultraviolet-B radiation on photosynthetic capacity, antioxidative potential and metabolites in Solanum tuberosum L. under varying levels of soil NPK

The impact of supplemental ultraviolet-B (sUV-B; 280–315 nm; +7.2 kJ m−2 d−1) radiation was studied on various physiological parameters, antioxidative potential and metabolites of Solanum tuberosum L. cv. Kufri Badshah plants under varying levels of soil NPK. The N, P and K treatments were: the recommended dose of N, P and K; 1.5 times the recommended dose of N, P and K; 1.5 times the recommended dose of N and 1.5 times the recommended dose of K. The recommended NPK level provided maximum protection to photosynthetic assimilation under sUV-B radiation, while stomatal conductance was best at 1.5 times the recommended NPK. Carbon dioxide assimilation declined maximally at 1.5 times the recommended N/K under sUV-B radiation. Plants grown at the recommended NPK and 1.5 times the recommended NPK levels showed higher superoxide dismutase, peroxidase and ascorbate peroxidase activities under sUV-B radiation compared to 1.5 times the recommended N/K levels. sUV-B significantly increased total phenolics and flavonoids in plants at the recommended and 1.5 times the recommended NPK, while flavonoids declined at 1.5 times the recommended N. This study clearly showed that NPK amendment provided maximum protection to photosynthetic assimilation of potato plants under sUV-B radiation, activating the antioxidative defense system as well as flavonoids. NPK at 1.5 times the recommended dose, however, did not cause any additional benefit to photosynthetic carbon fixation; hence the recommended dose of NPK is found to be the best suited dose of fertilizer under ambient as well as sUV-B regime.

Ultraviolet-B radiation modifies the quantitative and qualitative profile of flavonoids and amino acids in grape berries

Grapevine cv. Tempranillo fruit-bearing cuttings were exposed to supplemental ultraviolet-B (UV-B) radiation under controlled conditions, in order to study its effect on grape traits, ripening, amino acids and flavonoid profile. The plants were exposed to two doses of UV-B biologically effective (5.98 and 9.66kJm−2d−1), applied either from fruit set to ripeness or from the onset of veraison to ripeness. A 0kJm−2d−1 treatment was included as a control. UV-B did not significantly modify grape berry size, but increased the relative mass of berry skin. Time to reach ripeness was not affected by UV-B, which may explain the lack of changes in technological maturity. The concentration of must extractable anthocyanins, colour density and skin flavonols were enhanced by UV-B, especially in plants exposed from fruit set. The quantitative and qualitative profile of grape skin flavonols were modified by UV-B radiation. Monosubstituted flavonols relative abundance increased proportionally to the accumulated UV-B doses. Furthermore, trisubstituted forms, which where predominant in non-exposed berries, were less abundant as UV-B exposure increased. Although total free amino acid content remained unaffected by the treatments, the increased levels of gamma-aminobutyric acid (GABA), as well as the decrease in threonine, isoleucine, methionine, serine and glycine, revealed a potential influence of UV-B on the GABA-mediated signalling and amino acid metabolism. UV-B had an overall positive impact on grape berry composition.

Effects of Supplemental UV-B Radiation on Flower and Pod Formation in Soybean (Glycine maxL.) Crop.

Global climate change components such as carbon dioxide (CO2) concentration, temperature and ultraviolet-B (UV-B) radiation are continuously increasing. The objective of this study was to determine the effects of season-long exposures of supplemental UV-B. Effect of supplemental UV-B radiation on the flower and fruit formation in soybean was assessed. Supplemental UV-B radiation was given by halogen lamps. The study reveals that the number of flower was increased when plants were exposed to longer (2 and 3 hour) supplemental UV-B radiation in comparison to control. Pod formation was promoted at all supplemental UV-B radiation but it was observed maximum at shorter exposure (1 hour) of supplemental UV-B. At the maturity of the crop, the pod formation was recorded highest at 1 hr than at 2 hr and 3 hr supplemental UV-B radiation when compared with control. Overall results indicated that supplemental UV-B radiation promoted the growth of flower and fruit in soybean (Glycine max L.) crop.