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The effects of blue light-emitting diode (LED) light dosages on the growth and antioxidant properties of red pak choi (Brassica rapa var. chinensis 'Rubi' F1), tatsoi (Brassica rapa var. rosularis) and basil (Ocimum basilicum L. 'Sweet Genovese') microgreens were determined. The plants were grown within a controlled-environment growth chamber (21/ 17 ± 2 °C day/ night; 55 ± 5% relative air humidity) under five dosages (0%, 8%, 16%, 25%, 33%) of blue 447 nm in combination with red 638 nm, red 665 nm and far red 731 nm LEDs treatments (total PPFD ~ 302.5 µmol m-2 s-1; 16 h photoperiod). The influence of blue light dosage varied between microgreen species. The dosages of 16% and 33% led to significant lower hypocotyls and plant height of red pak choi, tatsoi and basil respectively. The highest concentration of ascorbic acid was determined in the tatsoi grown under 8% and in the red pak choi and basil under 16% blue light dosages. The tatsoi and basil showed the ability to accumulate more total phenols at 16-33% and the red pak choi at 8% blue light dosages. The similar trends on anthocyanin content and flavonols index were determined. The absence (0%) and the highest (33%) blue light dosage led to higher DPPH? radical scavenging activity in tatsoi and basil, but in pak choi it was significantly lower. [ABSTRACT FROM AUTHOR]

Darbo tikslas - palyginti puslaidininkinių lempų, sudarytų iš raudoną ir mėlyną šviesą emituojančių diodų, ir aukšto slėgio natrio lempų šviesos poveikį pomidorų daigams, auginamiems skirtinguose substratuose. Objektas - pomidorų hibridas 'Magnus'. Tyrimui naudoti skirtingi substratai: durpės bei vermikulito ir durpių substratas (santykis 3 : 2). Tyrimams naudotos lempos, sudarytos iš raudonos 665 nm ir mėlynos 451 nm bangos ilgių šviesą emituojančių diodų (LED). Mėlynos sudedamosios dalies fotonų srauto tankio dalis buvo 9 proc. nuo bendro 200 µmol cm-2 s-1 lempos fotonų srauto tankio. Kontroliniai augalai auginti po aukšto slėgio natrio lempomis (HPS). Tyrimo metu buvo palaikomas 16 val. fotoperiodas, 22/18 ± 2 °C dienos/nakties temperatūra ir 60-70 proc. santykinė oro drėgmė. Nustatyta, kad raudonos ir mėlynos spektro dalies šviesą emituojantys diodai (LED) vermikulito ir durpių substrate mažino pomidorų daigų aukštį, augalai suformavo mažiau lapų, jų plotas, žalia ir sausa masė buvo mažesni, augalai lėčiau vystėsi, tačiau buvo nustatytas didesnis chlorofilo a ir b kiekis, palyginti su po aukšto slėgio natrio (HPS) lempomis augintais daigais. Tyrimo pabaigoje šie augalai pasiekė V organogenezės etapą ir suformavo mažiau žiedų. HPS lempų šviesa skatino pomidorų daigų augimą ir vystymąsi, žiedynas pasiekė VII organogenezės etapą. Galima teigti, kad puslaidininkiniai šviesos šaltiniai bei vermikulito ir durpių substratas lėtina pomidorų daigų vystymąsi, tačiau daigai užauga neištįsę, kompaktiški ir kokybiški. The experiments were carried out at the phytotron complex of Plant Physiology Laboratory of the Lithuanian Research Centre for Agriculture and Forestry. The objective of our studies was to evaluate the effects of blue and red LED components on tomato transplant cultivation grown in different peat and vermiculite - peat substrates. The transplants of tomato hybrid 'Magnus' F1 were grown in phytotron chambers. The day/night temperature up to germination was 22-18 °C, and a 16 h photoperiod was maintained. Solid-state lighting lamps containing 665 and 451 nm light-emitting diodes (LEDs) were used in the experiments. The total photosynthetic photon flux density (PPFD) was 200 µmol cm-2 s-1, the blue component composed 9% of the total PPFD. Control tomato transplants were grown under the illumination of high-pressure sodium lamps (HPS). Substrate treatment: peat substrate and peat substrate with vermiculite (3 : 2 ratio). Our investigations revealed that under irradiation of red 665 nm and blue 451 nm light-emitting diodes the tomato transplants grown in vermiculite - peat substrate were smaller, had a smaller leaf area, the number of leaves, the hypocotyl diameter and the length, fresh and dry weight, but simulated chlorophyll a and b content. Their development was slower (V organogenesis stage) as compared to the transplants cultivated under high-pressure sodium (HPS) lamps (VII stages). Finally, our results show that the light-emitting diodes and vermiculite - peat substrate inhibit the development of tomato transplants. The tomato transplants are not elongated, compact and of high quality. These lamps may be more useful for supplemental lighting in greenhouse conditions where the total lighting flux contains background natural lighting. Therefore, these studies will be continued. [ABSTRACT FROM AUTHOR]

The experiments were carried out at the phytotron complex of Plant physiology laboratory of the Lithuanian Research Centre for Agriculture and Forestry. The objective of our studies was to evaluate the effects of blue and red LED components on cucumber transplant cultivation grown in different peat and vermiculite - peat substrates. The transplants of cucumber hybrid 'Mandy' F1 were grown in phytotron chambers. The day/night temperature up to germination was 22-18 °C, and a 16 h photoperiod was maintained. Solid-state lighting lamps containing 665 and 451 nm light-emitting diodes (LEDs) were used in the experiments. The total photosynthetic photon flux density (PPFD) was 200 µmol cm-2s-1, the blue component composed 9% of the total PPFD. Control cucumber transplants were grown under the illumination of high-pressure sodium lamps (HPS). Substrates treatment: peat substrate and peat substrate with vermiculite (3 : 2 ratio). Our investigations revealed that under irradiation of red 665 nm and blue 451 nm light-emitting diodes the cucumber transplants grown in vermiculite - peat substrate were smaller, had a smaller leaf area, the number of leaves, the hypocotyl diameter and the length, fresh and dry weight, chlorophyll a and b content. Their development was faster (VIII organogenesis stage) as compared to the transplants cultivated under high-pressure sodium (HPS) lamps (VI-VII stages). Finally, our results show that the light-emitting diodes and vermiculite - peat substrate stimulate the development of cucumber transplants. The cucumber transplants are not elongated, compact and of high quality. [ABSTRACT FROM AUTHOR]

The objective of our studies was to investigate the effect of solid-state short-wavelength sources of 455 nm blue light in combination with halogen lamps for growing of cucumber transplants. Experiments were performed in chambers and greenhouse of phytotron complex at the Laboratory of Plant Physiology, Institute of Horticulture. Cucumber hybrid 'Mandy' was used for the investigation. Cucumber transplants were grown under two illuminators. One of them was designed only from incandescent halogen lamps and another one from incandescent halogen lamps supplemented with 455 nm light-emitting diodes (LED s). It was established that supplemental blue LED s positively affected photosynthesis processes of cucumber transplants, though amount of blue light were not sufficient for significant decrease of plant elongation. [ABSTRACT FROM AUTHOR]

The objective of our studies was to investigate effect of solid-state short-wavelength sources of blue light in combination with high-pressure sodium lamps for growing of vegetable seedlings. Cucumber hybrid 'Mandy', tomato hybrid 'Cunero' and sweet pepper cultivar 'Reda' were used for investigation. There was compared growing of vegetable seedlings under high-pressure sodium lamps ‟SON-TAgro„ (PHILIPS) and under these lamps supplemented by blue light solid-state illuminators with LHXL-LR3C(Lumileds Lighting, USA) light-emitting diodes (447 nm). It was established that vegetable (cucumber, tomato, sweet pepper) seedlings were lower. Supplemental blue light during growing of vegetable transplant accelerated formation of flower buds. Significant after-effect of supplemental blue light on vegetable yield was not established. [ABSTRACT FROM AUTHOR]

The objective of our studies was to evaluate growth, development and yielding of tomato in greenhouse, which transplants were grown under various combinations of light-emitting diodes illumination. Tomato transplants were grown in phytotron chambers. System of five high-power solid-state lighting modules with the main 447, 638, 669 and 731 nm LEDs were used in the experiments. Supplemental LEDs of different wavelength were used in particular modules: LI - without additional LEDs, L2 -380 nm, L3 -520 nm, L4 -595 nm, L5 -622 nm. The similar photon flux density (PFD) in all modules was maintained by regulating PFD of 638 nm LEDs. Tomato seedlings were transplanted to peat substratum and grown in greenhouses. It was established that significant effect of illumination using different LEDs combination on growth and development of tomato hybrid 'Raissa' F1 transplants remained about one month after moving tomato to greenhouses. After-effect on photosynthesis pigments system of tomatoes in greenhouses lasted two weeks. Neither of light-emitting diodes combination had significant effect on early tomato yield. Yellow light, supplemental for the main LEDs combination, used for transplant illumination, decreased total tomato yield. [ABSTRACT FROM AUTHOR]