NaCl Stress-Induced Reduction in Grwoth, Photosynthesis and Protein in Mustard

Seed germination and early seedling growth, photosynthesis and protein activity of mustard were investigated under salt stress in two experiments. The NaCl concentrations in Hoagland solution were 0 (control), 50, 100 and 150 mM. Percentage of seed germination, germination rate, length, and fresh weight of the seedlings decreased significantly under salinity. Salt concentrations significantly reduced leaf area and number of leaves while salinity showed a non significant effect on leaf water content. Chlorophyll content enhanced considerably with the increasing NaCl concentration. Furthermore, Fv/Fm ratio and electron transport rate were also appreciably reduced by salt stress. In contrast, non- photochemical quenching coefficient increased significantly with increasing NaCl concentration. Net CO2 assimilation, stomatal conductance, transpiration rate, and intrinsic water-use efficiency decreased remarkably with increasing NaCl concentration while water use efficiency increased at 50 mM NaCl but then reduced. Correlation shows that gas exchange attributes had a significant positive relationship with chlorophyll fluorescence. There was an increase in the concentration of total protein content with the corresponding increase in NaCl level up to 100 mM. SDS-PAGE analysis showed that the intensity of band expression increased significantly as with increasing salt stress up to 100 mM but diminished at 150 mM NaCl.