Salinity strongly drives the survival, growth, leaf demography, and nutrient partitioning in seedlings of Xylocarpus granatum J. König

Abstract

Abstract: Salinity is increasing in the Sundarbans (Bangladesh) due to sea-level rise and the reduction of fresh water flow. Xylocarpus granatum is one of the most valuable mangrove tree species of the Sundarbans. We conducted a six-month long study to investigate the effect of salinity on the survival, growth, leaf demography, and nutrient partitioning in parts of X. granatum seedlings. Our results showed that most of the seedlings (90%) survived at 0 to 5 PSU salinity, and this survival percentage was found to decrease at higher saline conditions. Salinity of more than 25 PSU was lethal to the plants as no seedlings survived under these conditions. In this salinity (25 PSU), accelerated leaf fall coupled with a reduction in the new leaves caused loss of leaves. The relative growth rate (RGR) was higher at 0 to 5 PSU salinity, and conversely, a lower growth rate was observed with increased salinity. Higher saline conditions created stress, which inhibited nutrient (N, P and K) accumulation in different parts (leaf, stem, bark and root) of the seedlings. We concluded that salinity is a critical factor for the growth and survival of X. granatum either by inhibiting plant nutrient uptake or due to salinity related toxicity.