effects of bioactive compounds on chlorophyll fluorescence parameters of mexican lime seedlings (citrus aurantifolia swingle) under cold stress

Cold stress is one of the abiotic stresses that leads to most losses in citrus. mexican lime is one of the commercial citrus cultivars in the world, which is commonly used as a citrus rootstock in the southern regions of iran. that is one of the most sensitive citrus cultivars to cold stress. in order to investigate the ameliorating effect of some bioactive compounds on chlorophyll fluorescence parameters and electrolyte leakage of mexican lime seedlings under cold stress, a split-factorial experiment was conducted in the form of the randomized complete block design. the experimental factors included temperature (0 and -6 °c) as a main factor and foliar application of melatonin (0 and 500 μm), mannitol (0 and 50 μm) and acetic acid (0 and 15 μm) as sub-factors. according to the results, the combined application of melatonin + mannitol + and acetic acid, by improving the photosynthetic parameters, reduced the destructive effects of cold stress (0 and -6 ºc) on photosynthetic machinery in mexican lime seedlings. the highest area was observed in the treatment of melatonin + mannitol + acetic acid. the treatments of melatonin and melatonin + acetic acid had the highest values of fv/fm and fv/f0 and the lowest values of f0/fm at both temperatures compared to the control. in this study, the most appropriate parameters to identify the best treatments included area (total area between initial fluorescence curve and maximal fluorescence), maximum quantum yield of psii photochemistry (fv/fm), thermal dissipation quantum yield (f0/fm), and an indicator of the activity of the oxygen-evolving complex on the donor side of psii (fv/f0). therefore, the mentioned bioactive compounds, especially melatonin as well as acetic acid, are proposed to manage cold stress in mexican lime seedlings.

effects of bioactive compounds on chlorophyll fluorescence parameters of mexican lime seedlings (citrus aurantifolia swingle) under cold stress

cold stress is one of the abiotic stresses that leads to most losses in citrus. mexican lime is one of the commercial citrus cultivars in the world, which is commonly used as a citrus rootstock in the southern regions of iran. that is one of the most sensitive citrus cultivars to cold stress. in order to investigate the ameliorating effect of some bioactive compounds on chlorophyll fluorescence parameters and electrolyte leakage of mexican lime seedlings under cold stress, a split-factorial experiment was conducted in the form of the randomized complete block design. the experimental factors included temperature (0 and -6 °c) as a main factor and foliar application of melatonin (0 and 500 μm), mannitol (0 and 50 μm) and acetic acid (0 and 15 μm) as sub-factors. according to the results, the combined application of melatonin + mannitol + and acetic acid, by improving the photosynthetic parameters, reduced the destructive effects of cold stress (0 and -6 ºc) on photosynthetic machinery in mexican lime seedlings. the highest area was observed in the treatment of melatonin + mannitol + acetic acid. the treatments of melatonin and melatonin + acetic acid had the highest values of fv/fm and fv/f0 and the lowest values of f0/fm at both temperatures compared to the control. in this study, the most appropriate parameters to identify the best treatments included area (total area between initial fluorescence curve and maximal fluorescence), maximum quantum yield of psii photochemistry (fv/fm), thermal dissipation quantum yield (f0/fm), and an indicator of the activity of the oxygen-evolving complex on the donor side of psii (fv/f0). therefore, the mentioned bioactive compounds, especially melatonin as well as acetic acid, are proposed to manage cold stress in mexican lime seedlings.