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Influence of foliar application of polyamines on growth, gas-exchange characteristics, and chlorophyll fluorescence in Bakraii citrus under saline conditions

Khoshbakht, D., Asghari, M.R., Haghighi, M.
Photosynthetica 2018 v.56 no.2 pp. 731-742
Citrus reticulata, antioxidants, chlorophyll, electrolytes, enzymes, foliar application, gas exchange, leaves, photosynthesis, putrescine, salinity, salt stress, seedlings, sodium, sodium chloride, spermidine, spermine, water content
The effects of polyamines (PAs) on salt stress in Bakraii (Citrus reticulata × Citrus limetta) seedlings were studied. Foliar treatments by putrescine (Put), spermidine (Spd), and spermine (Spm) (0, 0.5, and 1 mM) were applied during the salinity period (0 and 75 mM of NaCl). PA-treated seedlings showed a lower content of Na⁺ and Cl– in leaves. Application of PAs increased net photosynthetic rate in salt-stressed plants and it contributed to the enhanced growth parameters. PAs application considerably induced growth improvement in Bakraii seedlings which was found to be associated with reduced electrolyte leakage, increased relative water content, chlorophyll fluorescence parameters, activities of key antioxidant enzymes, as well as increased photosynthetic pigment concentration under saline regime. These results showed the promising use of PAs, especially of Spd and Spm, for reducing the negative effects of salinity stress and improving the growth of citrus seedlings.