Morpho-physiological Alteration of Mangifera indica L. in Response to Sea Water Induced Salt Stress

Salinity is one of the biggest challenges in the southern part of Bangladesh, which is affecting the coastal ecosystem adversely. A pot experiment was conducted to find out the morpho-physiological changes in mango (Mangifera indica L.) seedlings in response to sea water induced salt stress at the Agroforestry and Environment research field of Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU). The experiment was laid out in a Randomized Complete Block Design (RCBD) with five replications, where four treatments, viz 4, 8, 12 dS m-1 salinity level (prepared from sea water), and the tap water (control) were imposed. The results indicated that plant height of mango shortened with the higher level of salinity and the declining magnitude was 28.44% over control at maximum salinity level. Number of leaves per plant of mango were reduced by 27.51% at 12 dS m-1 salinity level compared to that tap water, and the size of mango leaf was also reduced for salinity. Both shoot and root biomass of mango seedlings were significantly reduced due to salinity. The Salt tolerance index in mango was 56.76 only at 12 dS m-1. In case of physiological parameters, the lowest relative water content (RWC) was found in 12 dS m-1, while water saturation deficit (WSD) and water uptake capacity (WUC) were found to be the lowest in control for this plant. Water saturation deficit and water uptake capacity were increased with the increment of salinity level. Total chlorophyll and carotenoid content of mango were decreased by 66.27% and 61.07%, respectively, at the highest salinity level. Proline content of mango increased by 73.07% at 12 dS m-1 salt level in comparison to that of seawater devoid control plants. Considering the overall results, it can be concluded that, although mango seedlings were significantly affected by high salinity (12 dS m-1), but can survive up to moderate salinity (8 dS m-1) at sapling stage.