Evaluation of Morphophysiological and Biochemical Features in Young Plants of Khaya senegalensis Under Increasing Salinity

Abstract

A greenhouse study was carried out to evaluate the effects of increasing sodium chloride (NaCl) concentrations in a nutrient solution on growth-related morphophysiological and biochemical features during development of young plants of African mahogany (Khaya senegalensis). The NaCl concentrations were 0 mM (1.0 dS m^-1), 20 mM (3.38 dS m^-1), 145 mM (15.14 dS m^-1), 270 mM (29.90 dS m^-1), 395 mM (42.61 dS m^-1) and 520 mM (53.60 dS m^-1). Morphological features were negatively affected by increasing NaCl concentrations, except for plant height, which had no significant effect. Relative water content was not affected, whereas water potential decreased, suggesting osmotic adjustment. Whole plant dry mass was reduced, especially on roots, whose dry mass reduced up to 66% lower than in control. Regarding biochemical features, chlorophyll, chlorophyll content was reduced by salinity stress from 15.14 dS m^-1, whereas reducing sugars, starch and proline contents were increased. We conclude that in the early development Khaya senegalensis is tolerant to salinity stress, since plant height was not affected, whereas the other morphophysiological parameters became significantly lower than the control only from moderate salinity levels. Salinity tolerance must have probably been favored by the osmotic adjustment provided by increased compatible osmolytes.