Impacts of Climate Change Induced Salinity Intrusion on Nitrogen Fixing Microbial Community of Sesbania bispinosa and Histo-Architecture Changes of Eichhornia crassipes and Enydra fluctuans tissues

Abstract

The salinity intrusion due to the effect of global climate change is a major concern in the coastal regions of the world. It has severe effect of making surface-water and ground-water saline which hampers the ecosystems and extinctions of different species. The salinity intrusion effect on the two species of freshwater plants Eichhornia crassipes and Enydra fluctuans and a terrestrial plant species Sesbania bispinosa was examined in this study by introducing them in salt stress. For the terrestrial legume plant Sesbania bispinosa, the effect of the salinity in the survival and growth of Nitrogen fixing Rhizobium in the nodules of the plants was examined. Salt concentrations which were introduced in the YEMA medium were 10, 20, 30 and 40ppt and the Rhizobium bacteria showed effect for it. Four rhizobial strains showed growth in all the concentrations (Ses 17, Ses 18, Ses 19 and Ses 27) which define that these are high salt tolerant Rhizobium species and can be used to make better and sustainable manure from them. Other strains showed either growth or incomplete growth in 10 ppt of salt (Ses 20, Ses 21, Ses 22, Ses 23, Ses 24, Ses 26 and Ses 28 to Ses 30) but couldn’t survive in the higher concentration of salt than 10ppt. One species (Ses 25) couldn’t survive in any of the salt concentration. Beside the Rhizobium survivability study, the histological study in the freshwater plants showed deformity in the root and tuber tissue structure of those plants. The epidermis of the both plant’s tissue was thickened at 30ppt of salt due to the osmotic pressure created by salt stress. There was expansion in the vascular bundle of those tissues which was identified at 30ppt salt which was caused due to the inhibition of the process of water up-take of those plants. These findings indicate that salinity intrusion constrains Rhizobium growth and causes histo-architecture changes in the root tissues of plants which can help to combat against the salinity intrusion in the coastal region countries like Bangladesh..