Our thesis addressed the growth response of the plant lamb’s lettuce to different light treatments. The aim of this study was to achieve an increase in the yield by extending the photoperiod with supplemental lighting without getting into extension growth or reaching the flowering phase. In the experiment that was conducted in February and March of 2019 in a greenhouse of the Department of Agronomy at the Biotechnical Faculty, cultivar 'Vit' was used. The plants were exposed to three different light treatments. In the first one, the day was prolonged for two hours with combination of red, white and blue light (R+W+B); in the second one, the two hours supplemental lighting included far-red, white and blue light (FR+W+B) and in the third treatment, the control plants were not treated with additional lighting. The supplemental lighting, for which we used light-emitting diodes (LED), was, in both treatments, applied in Photosynthetic photon flux density (PPFD) of 170-200 µmol m-2 s-1. During the 45-days period 4 measurements were taken. The results have shown that on plants treated with supplemental lighting had higher fresh and dry weight and higher extension of the shoot apex. The highest average results in these parameters were observed in plants given the supplement lighting treatment of FR+W+B. Their fresh weight was 2.7,7 g/plant and dry weight was 0.,45 g/plant. Plants cultivated under no supplemental lighting had the lowest fresh (2.2 g/plant) and dry (0.32 g/plant) weight as well as the least grown shoot apex. The highest results in fresh and dry weight corresponded with the extension growth of the shoot apexes of plants under FR+W+B treatment. The length of them were 11,9 mm and their growth from the starting point was 117 %. The shoot apexes of plants under R+W+B lighting treatment achieved an average growth of 115 %. During the experiment the apex elongation was most even under R+W+B. The shoot apex of control plants elongated for 93 % during experiment. The observed plants have shown the biggest growth during the period between T0 and T1. The results have shown that extending the photoperiod with supplemental lighting does not significantly affect the number of leaves or their total surface area. Furthermore, no significant differences in photosynthetic rate were observed between light treatments, which could be attributed to the fact that all plants were for the most part of the light period exposed to equal amounts of sunlight.
|