Anatomical and physiological adaptations in aquatic ecotypes of Cyperus alopecuroides Rottb. under saline and waterlogged conditions

• Populations of Cyperus alopecuroides are differently adapted to stress conditions.
• Tolerant ecotype BW showed better growth under stress.
• BW ecotype had higher photosynthetic efficiency, K+ uptake and proline accumulation.
• Lysogenous aerenchyma in roots was more prominent in ecotype FW.
• Ecotype BW had specific anatomical features for survival in stressful environments.

An experiment was conducted to investigate structural and functional acclimation in two ecotypes of Cyperus alopecuroides Rottb. under saline and waterlogged conditions. A salt sensitive ecotype was collected from fresh river water (FW) and a salt tolerant ecotype from polluted brackish water (BW). The experiment was conducted in a 2-factorial (salinity, ecotyope) completely randomized design with five replications. Three salt regimes were maintained during the experiment, 0 (control, no salt), 150 and 300 mM NaCl. Ecotype BW was better adapted to salinity + waterlogging than ecotype FW from fresh water of the River Ravi. Waterlogging was simulated as ecotype BW showed greater root and shoot length, root and shoot fresh and dry biomass, and bract area, higher chlorophyll a and b concentration, net assimilation rate, water use efficiency, turgor potential, root and shoot K+ and accumulation of free proline, but lower transpiration rate and shoot Na+ uptake than ecotype FW under stressful conditions of salinity/waterlogging. Root lysogenous aerenchyma was more prominent in ecotype FW than in ecotype BW. In addition, ecotype BW had large cortical cells, a thick endodermis barrier, high sclerification and large metaxylem vessels, all contributing to efficient water and solute conduction under combined salinity and waterlogging stress; hence contributing substantially to better survival of this ecotype in harsh stressful environments.