Effect of salt stress on chlorophyll content, fluorescence, Na+ and K+ ions content in rape plants (Brassica napus L.).

摘要

To investigate the effect of salt stress on chlorophyll content and fluorescence, sodium (Na+) and potassium (K+) ion content of rape (Brassica napus) plants, 10 genotypes were subjected to salinity levels (control (2.5), 6, 10, 14 and 18 dS m-1) for 30 days in hydroponics. Salt treatments were imposed during root establishment stage (4 leaves). The quantum yield of photosystem II from light-adapted ( Phi PSII) and dark-adapted leaf (Fv/Fm), photochemical quenching (qP) and minimal fluorescence from dark-adapted leaf (Fo) were affected by salinity. Genotypes MHA4921 and Hyola 401 had the highest shoot dry weight at the 2 higher salt treatments (14 and 18 dS m-1) and was the most tolerant to salinity. Chlorophyll (chl) fluorescence attributes were generally affected by salinity stress, except in the 2 salt-tolerant genotypes and thus could be used as a tool for screening for salinity tolerance. Chlorophyll content (SPAD units) changed significantly in all genotypes, except in salt-tolerant ones. Shoots Na+ content increased by increasing salinity levels, but in MHA4921 this increase was higher than the other genotypes and may be related to the decline in the osmotic potential of cellular contents. Rape ability to accumulate Na+ in response to salinity is one of the major criteria of salt tolerance. K+ content in shoots at the different levels of salinity in MHA4921 and Hyola 401 was higher than the other genotypes.