engleski

Effect of Prolonged Photoperiod on Light-Dependent Photosynthetic Reactions in Cannabis

Industrial hemp is a fast-growing, short-day plant, characterized by high biomass yieldsand low demands for cultivation. To manipulate growth, hemp is usually cultivated under prolongedphotoperiods or continuous light that could cause photooxidative damage and adjustments ofphotosynthetic reactions. To determine the extent of changes in photosynthetic response causedby prolonged light exposure, we employed chlorophyllafluorescence measurements accompaniedwith level of lipid peroxidation (TBARS) and FT-IR spectroscopy on twoCannabiscultivars. Plantswere grown under white (W) and purple (P) light at different photoperiods (16/8, 20/4, and 24/0).Our results showed diverse photosynthetic reactions induced by the different light type and by theduration of light exposure in two cultivars. The most beneficial condition was the 16/8 photoperiod, regardless of the light type since it brought the most efficient physiological response and the lowestTBARS contents suggesting the lowest level of thylakoid membrane damage. These findings indicatethat different efficient adaptation strategies were employed based on the type of light and theduration of photoperiod. White light, at both photoperiods, caused higher dissipation of excesslight causing reduced pressure on PSI. Efficient dissipation of excess energy and formation of cyclicelectron transport around PSI suggests that P20/4 initiated an efficient repair system. The P24/0maintained functional electron transport between two photosystems suggesting a positive effect onthe photosynthetic reaction despite the damage to thylakoid membranes.

industrial hemp ; G-band ; H-band ; OJIP ; TBARS ; FT-IR

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