||The experiment focused on determining the assimilator pigments content in the cotyledons of the black pine plantlets (Pinus nigra Arn.) derived from seeds germinated and grown for 21 days, 16 hours/day, under light emitted by Light-Emitting Diodes (LEDs), of different colours (respectively, of different wavelengths). The light intensity was constant, of 1200 lx. The highest chlorophyll a content was recorded at the seedlings exposed to the red light produced by LEDs, which, compared with the plantlets grown in natural light, marked an increase of 26.3%, and, as against to those exposed to fluorescent white light, was 18.1% higher. Instead, the seedlings exposed to white LEDs light, in relation to those illuminated with natural light, have registered the highest values of chlorophyll b (+159%) and carotenoid pigments (+95.2%), and of the total chlorophyll pigments content (+74.7%), respectively, of the total assimilator pigments (+77.1%). The lowest values of the assimilator pigments content were marked at the plantlets exposed to the green light of LEDs, at which the chlorophyll a content was reduced with 25.7%, and the content in chlorophyll b with 31.3%, in comparison with the results noted at the group of plantlets lighted with white fluorescent tubes; therefore, the total green pigments were diminished with 28.9%, respectively, the content in total asimilator pigments with 28.8%. Thus, from all the types of lightings used, the most effective light for the assimilator pigments accumulation, in the cotyledons of black pine seedlings, proved to be the white one of LEDs
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