Seasonal Physiological & Biochemical Responses of Three Medicinal Halophytes From Karachi University Campus

Abstract

Three medicinally important halophytes: Cyperus rotundus L., Dactyloctenium scindicum Boiss. and Lasiurus scindicus Forssk., were chosen from Karachi University campus to explore seasonal physiological and biochemical responses. Seasonal and diurnal water potentials (Ψ) showed a great variation among species. Pre-dawn water potential (ΨPD) was higher before and after rains in all test species than the mid-day water potential (ΨMD) corresponding to the soil matric potential (Ψsoil), electrical conductivity (EC) as well as % soil moisture (SM). Lasiurus scindicus had lowest ΨPD & ΨMD in comparison to C. rotundus and D. scindicum before rainfall. Similar trends were observed for osmotic potential (ΨS) of all species. Both ΨMD & Ψs substantially increased in D. scindicum and L. scindicus after rainfall, whereas, C. rotundus showed no significant change and this species also maintained highest turgor (ΨP). Leaf stomatal conductance (gS) was higher in C. rotundus while proline (PRO) in D. scindicum before rain. Leaf PRO decreased while gS increased after rains and this increase was 3 fold in D. scindicum. Sodium (Na+) and chloride (Cl-) were higher than potassium (K+) in all species before rain with maximum values in D. scindicum. In general Na+ and Cl- decreased while K+ increased in all species after rain. Total soluble sugars (TSS) were consistently higher in C. rotundus while D. scindicum maintained higher Na+ and Cl- even after rains compared to other species. The differences in ecophysiological responses owing to differences in life forms suggest the existence of plant species in different habitats.