Water conservation strategies in big cordgrass (Desmostachya bipinnata L.) for ecological success in hyper-arid and saline-arid environments

Abstract

This study was conducted to investigate water conservation strategies in the above ground parts of Desmostachya bipinnata L., a perennial grass growing in populations of arid areas of the Punjab to identify variability in the anatomical traits that enable them to survive in water deficit conditions. Key structural modifications contributing to the ecological success and adaptation against heterogeneous environments included water conservation via development of additional water storage parenchyma, efficient conduction of solutes through wide metaxylem vessel (7947 µm2), minimization of water loss by intensive sclerification in some populations from Kallar Kahar (hyper-saline lake) and Pakka Anna (highly saline wasteland with D ratio:13.29) to avoid water loss. Populations from the most dry habitats, that is, in Cholistan (inter-dune desert flat with D ratio:43.17) had numerous small metaxylem vessels (1727 µm2). Saluwali (Cholistan Desert plain D ratio:30.4) populations showed intensive sclerification in stem vascular region and high density, wider metaxylem vessel oriented in dimensions different than other populations. A very unique feature observed in stems of Cholistan desert margin Kachakho, Pirowal plantation and Saluwali populations was the development of single-large metaxylem vessels instead of a pair usually found in plants. Another characteristic feature observed in stems, leaves and leaf sheath of some populations was differentially developed aerenchyma and bulliform cells ranging from small to large prominent and deeply inserted. In conclusion, D. bipinnata populations showed high but habitat-specific variability among the traits recorded, which provided this species a great potential to colonize arid and salt-affected areas.