The Photosynthetic Performance of Red Leaf Lettuce under UV-A Irradiation (original) (raw)
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Plants, 2022
The optimization of plant-specific LED lighting protocols for indoor plant growing systems needs both basic and applied research. Experiments with lettuce, Lactuca sativa L., plants using artificial lighting based on narrow-band LEDs were carried out in a controlled environment. We investigated plant responses to the exclusion of certain spectral ranges of light in the region of photosynthetically active radiation (PAR); in comparison, the responses to quasimonochromatic radiation in the red and blue regions were studied separately. The data on plant phenotyping, photosynthetic activity determination, and PAM fluorometry, indicating plant functional activity and stress responses to anomalous light environments, are presented. The study on carbon isotopic composition of photoassimilates in the diel cycle made it possible to characterize the balance of carboxylation and photorespiration processes in the leaves, using a previously developed oscillatory model of photosynthesis. Thus, th...
Acta Physiologiae Plantarum
Plants growing under natural conditions are constantly exposed to ultraviolet (UV), primarily UV-A, radiation. Grass pea (Lathyrus sativus L.) is a legume species resistant to harsh growing conditions, such as drought, salinity or periodic flooding. Due to the advantageous composition of seeds, it is used for consumption in such regions as South Asia or East Africa where high intensity of UV radiation occurs. Absorption of this spectral range causes changes in the photosynthetic apparatus of plants, including damage to the photosystem II (PSII) reaction centres. The aim of the work was to examine whether the use of the combination UV-A: red light as a source of radiation would enable quick acclimatization of the photosynthetic apparatus of grass pea to the negative effect of UV-A radiation. 14-day-old plants were exposed to UV-A:red radiation for 48 h. The plants exposed to UV-A:red radiation showed enhanced effective efficiency of PSII and increased total electron carriers, which enabled more effective photosynthesis at higher values of radiation intensity in comparison with control plants, kept under white LED light. At the same time, there were no statistically significant differences in both the photosynthetic pigment contents and the level of lipid peroxidation. The obtained results indicate that the observed increase in the efficiency of CO 2 carboxylation after short-term UV-A:red radiation has resulted from the efficient linear electron transport due to maintaining the effective oxygen evolving complex (OEC) and increased total electron carriers.
Aims: The aim of the present study was to investigate some biochemical changes in field grown lettuce (Lactuca sativa L. cv Romaine) plants in terms of importance of the accumulation of anthocyanins, flavonoids and photosynthetic pigments as well as photosynthetic limitations which changed during exposure of plants to drought stress and UV-B radiation in order to circumvent the deleterious effects of these Stresses. Place and Duration of Study: The experiment was conducted under filed conditions from November 2012 to January 2013, at the Agricultural Research Center, KAU. Methodology: The experimental design was a factorial arrangement in randomized complete blocks with four replicates. The first factor was UV-B (300 nm). The second factor was irrigation regime (complete irrigation to field capacity and limited irrigation. Gas exchange measurements were carried out using a LI-6200 portable IRGA. Chlorophyll fluorescence of Fv/Fm was measured by PAM 2000 fluorometer. Biochemical analyses and antioxidant enzymes assays were performed according to the appropriate methods. Results: Exposure of lettuce plants to enhanced UV-B radiation and drought stresses (DS) negatively and significantly affected the process of photosynthesis including CO2 assimilation (PN), stomatal conductance to water vapour (gs) and transpiration rate (E). However, the amplitude of the effects of both stressors was dependent on the interactions
HortScience, 1991
This study evaluated the potential of high photosynthetic photon flux (PPF) from high-pressure sodium (HPS) lamps, alone or in combination with metal halide (MH) plus quartz iodide (QI) incandescent lamps, to support lettuce growth, with or without N supplementation. Varying exposures to radiation from combined HPS, MH, and QI lamps influenced dry weight gain and photosynthetic pigment content of hydroponically grown `Black-Seeded Simpson' lettuce (Lactuca sativa L.) seedlings. Cumulative leaf dry weight declined with increasing exposure, up to 20 hours per day, to 660 μmol·m-2·s-1 of photosynthetically active radiation (PAR) from HPS lamps concomitant with constant 20 hours per day of 400 m mol·m-2·s-1 from MH + QI lamps. Leaves progressively yellowed with increasing exposure to radiation from the three-lamp combination, corresponding to lower specific chlorophyll content but not to specific carotenoid content. Lettuce grown under 20-hour photoperiods of 400, 473, or 668 μmolm·...
Plant, Cell & …, 2011
Plant responses to solar UV radiation are numerous and have often been considered from a perspective of negative outcomes for plant productivity. In this study, we used two experimental approaches consisting of: (1) field-based spectrally modifying filters in addition to (2) controlled indoor exposure to UV-B, to examine the effects of UV radiation on growth and photosynthetic performance of lettuce (Lactuca sativa L.) seedlings. Various aspects of growth were affected in plants grown under a UV-inclusive environment compared to a UV-depleted environment, including reductions in leaf expansion, increases in leaf thickness and the rate of net photosynthesis. After transplantation to a uniform field environment, lettuce plants initially propagated under the UV-inclusive environment exhibited higher harvestable yields than those from a UV-depleted environment. In controlled conditions, photosynthetic rates were higher in plants grown in the presence of UV-B radiation, and relative growth of plants pre-acclimatized to UV-B was also increased, in addition to higher maximum photochemical efficiency of photosystem II (PSII) (Fv/Fm) following subsequent exposure to high photosynthetically active radiation (PAR) and temperature stress. Our findings are discussed within the context of sustainability in agriculture and the paradigm shift in photobiology which such beneficial responses to UV radiation could represent.
Scientia Horticulturae, 2020
Light drives photosynthesis and regulates plant morphology, physiology, and phytochemical content. Using light emitting diodes (LEDs), customized spectra can be created, including spectrum that simulates solar light. The aim of this study was to assess the growth, development, and phytochemical content at three marketable stages of lettuce (transplant, baby-leaf, and head-lettuce) under a sun-simulated spectrum and common light spectra used in indoor growing systems. Oakleaf red (Salanova® 'Red Oakleaf') and green (Salanova® 'Green Oakleaf') lettuce were grown under seven spectra. A sun-simulated light treatment (SUN) was created with 5 % ultraviolet-A (UV-A), 20 % blue (B), 26 % green (G), 26 % red (R), and 23 % far-red (FR) light as percent photon flux density (PFD). In addition, five treatments of differing blue:red (B:R) ratios were evaluated: 0B:100R (100R), 20B:80R, 50B:50R, 80B:20R, and 100B:0R (100B) and fluorescent white light was used as a control (6500 K). Plants were provided with 200 ± 0.7 μmol•m −2 •s −1 biologically active radiation (300-800 nm) for 18 h and grown at 20.0 ± 0.2°C temperature. Fresh mass of lettuce in the SUN treatment was not significantly different when compared to B:R light treatments in all harvest dates despite the 36 % greater photosynthetic photon flux density (PPFD) in B:R treatments. Plant dry mass on day 17 of' Green Oakleaf' and 'Red Oakleaf' grown under 20B:80R was 15-39 % greater than those grown in 100B and SUN. When calculating total dry mass accumulation to cumulative yield photon flux density (YPFD), plants in SUN treatment accumulated the same dry mass per YPFD input (mg mol −1). Leaf area at day 42 of plants in 100B, SUN, and FL was 39-78 % greater than plants in B:R treatments. At final harvest (day 42), plant stem length in SUN was 2.1-4.4 times longer than in all other treatments, indicating bolting and flowering initiation. Both total phenolic and anthocyanin concentrations were greater in the B:R treatments than in SUN, 100R, and 100B treatments. This study presents baseline information for lettuce responses under LED-simulated SUN spectrum when compared to common B:R treatments and offers insights on lettuce growth and morphology under different spectra at multiple growth stages.
B I O L I F E EFFECT OF UV-A RADIATION ON PHOTOSYNTHETIC PIGMENTS OF SELECTED CROP PLANTS
The present work deals with the effect of UV-A radiation and UV-A along with growth regulators on certain pigments in four crop plants, red gram, groundnut, wheat and ragi. Plants were exposed to UV-A radiation for two hours (2 hr) and four hours (4 hr) daily and UV-A irradiated plants were given chemical treatment, AA, IAA and SA at every fortnight starting from seed stage to yield level. At every fortnight the total chlorophyll content, chlorophyll a (chl-a) and chlorophyll b (chl-b) content were estimated. Treatment with UV-A decreased chlorophyll content. Chlorophyll a was more affected than chl-b. Chlorophylls were found to be more sensitive to UV-A radiation in all the four crop plants studied. The harmful effect of UV-A radiation on pigments was found to be less in AA, IAA and SA treated plants. Ragi plants were found to be more sensitive to UV-A radiation and AA being a powerful antioxidant was found to be an effective possible antidote to UV-A radiation followed by SA and IAA. The present work reveals that UV-A has adverse effects on photosynthetic pigments which ultimately lead to the decrease in the productivity and yield of the crop plants like UV-B radiation.
Plants
This study focused on the physiology, growth and antioxidant activity response of hydroponically grown lettuce (Lactuca sativa L.) under sole-source LED lighting of differing spectra. Lighting spectra were provided by differing combinations of LEDs of three different peak wavelengths, (Blue 435, Blue 450, and Red 663 nm) with ratios of B450/R663: 1.25 ± 0.1, B450/R663: 1.25 ± 0.1, and B450/R663 1:1 at two light intensities of photosynthetically active radiation (PAR) (270 μmol m−2 s−1 and 60 μmol m−2 s−1). A further experiment was conducted, in which Blue and Red LEDs were supplemented with Green (Blue 450, Red 663, and Green 520 nm) with ratios of B435/R663: 1.25 ± 0.1, B450/R663/G520: 1/0.73/0.26, and B450/R663: 1.25 ± 0.1. LED light intensities under the different spectra were adjusted to deliver the same level of PAR (270 ± 20 μmol m−2 s−1). Results from the first experiment showed that increased fraction of blue 435 nm in combination with red light at 663 nm at high irradiance ...