Structural and Functional Determinants of Physiological Pliability in Kyllinga brevifolia Rottb. for Survival in Hyper-Saline Saltmarshes

The role of morpho-anatomical adaptations of six Kyllinga brevifolia populations in successfully invading hyper-saline environments was investigated. Physiological and anatomical characteristics showed a high degree of plasticity indicating its adaptability potential to a variety of environmental conditions. The population from hyper-saline saltmarsh Sahianwala was exposed to physiological drought for a long time and its survival relied on the prevention of water loss attained by decreased stomatal density and area, lignin deposition in the inner and outer cortical region, especially outside vascular tissue. Larger cells of cortical storage parenchyma aided in water storage and wide metaxylem vessels in better conduction of solutes. Higher accumulation of shoot Ca2+ in this habitat protected neutralized the impact of the enhanced shoot and root Na+ ion uptake. Organic osmoprotectants like total free amino acid, proline, soluble proteins, and sugars accumulated in a higher quantity that contributed towards an osmotic adjustment in Sahianwala population. Population from seasonal inundation (Treemu Headworks) showed larger root aerenchyma to supply sufficient oxygen for respiration, broader xylem vessels for better water and nutrient conduction, and greater density of leaf stomata for better transpiration. Maximum shoot and root length, total leaf area, and water potential were observed in the least saline Chinyot population indicating its best growth potential in a slightly saline aquatic environment. Each population showed specific physiological and anatomical modifications to colonize their respective habitats.