Photosystem II Efficiency of Primed Canola under Salt Stress

This experiment was conducted to investigate the role of priming in regulating growth and photosynthesis in salt-acclimated canola plants. Salt stress caused a significant decrease in total dry masses, whereas seed priming with hydrogen peroxide (H2O2), nitric oxide (NO) or H2O2+NO mitigated the salt-induced inhibitory effects on the plant growth under acclimated conditions. The adverse effects of salinity on shoot and root lengths were alleviated only by combined H2O2 and NO priming in acclimated canola plants. Under salt-stress conditions, the contents of photosynthetic pigments were reduced in non-acclimated plants, whereas the priming with H2O2+NO alleviated the inhibitory effect of salinity on the chlorophyll a and carotenoids contents. Measuring the chlorophyll a fluorescence parameters indicated that NaCl markedly decreased the maximum quantum yield (Fv/Fm), the quantum yield of electron transport (ΦEo) and the oxygen-evolving complex efficiency of PSII (Fv/Fo) in non-acclimated canola leaves showing photoinhibition of PSII, but the priming with H2O2+NO improved these parameters under salt stress. Our results suggested that priming of canola seeds with H2O2+NO significantly increased photosynthetic pigments accumulation, which was associated with the improvement of the photochemical efficiency, resulting in better plant growth under salt stress.