weight. Photosynthetic pigment levels were lower under LED light compared to control lamps. Phenolic acids and flavonoids were identified in M. communis leaf extracts. Myricetin was the major constituent with highest concentration under red LEDs and highest BA level. Keywords Myrtle · Light quality · Photosynthetic pigments · Secondary metabolites · HPLC Abbreviations LED Light emitting diode B 100% blue LED RB 70% red and 30% blue LED R 100% red LED C Control fluorescent light BA 6-Benzyladenine NAA 1-Naphthaleneacetic acid MS Murashige and Skoog medium HPLC High performance liquid chromatography PPFD Photosynthetic photon flux density Communicated by Sergio J. Ochatt.

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A mixture of red and blue light-emitting diodes (LEDs; at a ratio of 7:3, respectively) were used to analyze the effects of different photosynthetic photon flux densities (PPFDs) (40, 80, and 120 µmol m−2 s−1 hereafter known as LED 40, 80, and 120, respectively) on the micropropagation of Gerbera jamesonii Bolus shoots. The experiment also examined the effect of 6-benzyladenine (BA) in 1, 2.5, and 5 µM concentrations in the media. Biometrical observations and analyses of leaf morphometry and photosynthetic pigment content were conducted. Shoot multiplication increased with an increasing BA concentration. A PPFD of 80 µmol m−2 s−1 and 5 µM BA is suggested as efficient for shoot propagation and economically viable. LED 120 increased the leaf blade area and its width, and circularity and elongation ratios. The intensity of light did not affect the fresh weight, which increased at higher BA concentrations (2.5 and 5 μM). The dry weight content decreased with increasing cytokinin concentration; the greatest content was observed on media with 1 µM BA under PPFD 120 µmol m−2 s−1. LED 80 increased the photosynthetic pigments content in the leaves in comparison to the standard intensity of LED 40. Increased BA concentration raises the content of chlorophyll a.

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The experiment evaluated the influence of different light qualities and 6-benzyladenine (BA) concentration in a medium on the leaf response of multiplied Gerbera jamesonii Bolus ex Hook. f.‘Big Apple’ shoots. Three different light-emitting diode (LED) spectra—100% blue (B), 100% red (R) and red and blue mixture (7:3, RB)—were used, and a fluorescent lamp was used as a control (Fl). Concentrations of BA in Murashige and Skoog (MS) medium were 1, 2.5 and 5 µM. Leaves developed under 100% blue light had a lower frequency of stomata and a smaller area as compared with those from plants exposed to light with red in spectrum. Under 100% red light, the leaf area and the frequency of stomata increased along with growing concentration of BA in the medium. The thickest mesophyll was spotted in the cross-section of leaves exposed to the blue LED light. Leaves developed under the 100% red light had the thinnest mesophyll layers. Increasing concentration of BA in the medium resulted in enhanced leaf blade thickness. The cross-section of leaf vascular bundles was only half of that in petioles. The leaves under the LED combinations had larger vascular bundles than those under fluorescent light. The highest level of photosynthetic pigments was noticed in the leaves grown under LED R and RB lights. Our study demonstrated that 2.5 µM BA and a mixture of blue and red light provided by LED improved leaf quality during multiplication of gerbera shoots.

Cultures of Nasturtium officinale were cultivated in vitro under illumination with different wavelengths of light-emitting diode (LED) light (white LED light—WLED, blue light—B, red light—R, 70% red and 30% blue light—RB, 50% green, 35% red and 15% blue light—RBG, 50% yellow, 35% red and 15% blue light—RBY, 50% far red, 35% red and 15% blue light—RBfR, 50% UV, 35% red and 15% blue light—RBUV, darkness—D), and under white fluorescent light (WF)—control conditions. The study investigated the influence of the applied lighting conditions on biomass growth and the production of glucosinolates, phenolic compounds, as well as photosynthetic pigments, and soluble sugars. The study showed a significant beneficial effect of the RBG light on biomass growth (Gi = 11.81 after 20 days) and the production of glucosinolates. The total glucosinolate content under these conditions increased 5.8 and 1.4 times in comparison with the WF light and D condition, respectively, reaching 237.92 mg 100 g−1 DW. The production of phenolic compounds, sugars, and photosynthetic pigments was comparable to the production under the control conditions. The antioxidant potential of extracts from the cultivated biomass was assessed by the CUPRAC, DPPH, and FRAP assays. Extracts obtained from the biomass of cultures grown under the RBG light had an antioxidant potential similar to that of the control cultures. This is the first report providing evidence of the stimulating effect of light quality on the biomass yield and production of glucosinolates by N. officinale microshoot cultures in vitro.

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The effect of BA and GA3on the shoot multiplication ofin vitrocultures of Polish wild rosesThe experiment was conducted using five species of roses naturally occurring in Poland:Rosa agrestis(fieldbriar rose),R. canina(dog rose),R. dumalis(glaucous dog rose),R. rubiginosa(sweetbriar rose), andR. tomentosa(whitewooly rose), from thein vitrocollection of the Department of Ornamental Plants of the University of Agriculture in Kraków. We examined the effect of cytokinin BA (1-10 μM) added to an MS medium (Murashige and Skoog 1962) on auxiliary shoot multiplication. The second group of test media contained BA (1-5 μM) and gibberellin GA3(0.3-1.5 μM). The cultures were maintained at a phytotron temperature of 23/25°C (night/day), 80% relative humidity, with a 16-hour photoperiod and PPFD of 30 μmol m-2s-1, and cultured in five-week cycles. The highest multiplication rate was obtained forR. caninaandR. rubiginosa(4.1 shoots per one explant) andR. dumalis(2.9 shoots per one explant), when shoots were multiplied on an MS medium supplemented with 1 μM BA and 1.5 μM GA3. Multiplication was the weakest inRosa tomentosaindependent of the medium used.