Effect of Salinity on Seed Germination, Growth, Water Relations and Ion Accumulation of Zygophyllum propinquum

Abstract

Information about the seed biology of medicinally important xero-halophyte Zygophyllum propinquum is limited. Therefore responses to different abiotic factors during seed germination, recovery and viability of Z. propinquum were studied. Germination and recovery responses to different thermoperiods (10/20, 15/25, 20/30 and 25/35 oC), photoperiods (12h light/12h dark and 24h dark), salts (chloride and sulphate salts of Na, K, Ca and Mg), and mannitol were studied. Seeds were non-dormant and maximally germinated (~ 95 %) in distilled water. Relatively higher seed germination was observed under moderate (15/25 and 20/30 oC) temperature regimes and in 12h photoperiod. Increases in salinity decreased seed germination and only few seeds (~26 %) germinated at 200 mM NaCl. However, most un-germinated seeds from high salinity showed recovery of germination when transferred to water. Among chloride (Cl- ) salts inhibitory effects at -1.2MPa under light were in following order of magnitude: KCl > CaCl2 > NaCl = MgCl2. While, for sulphate (SO4 --) salts inhibitory effects were in following order: K2SO4 > MgSO4 > Na2SO4. Germination inhibition under various osmotic treatments of mannitol was generally lesser than the iso-osmotic NaCl treatments. These results indicate that seeds of Z. propinquum were moderately salt tolerant and preferred to germinate under moderate temperatures and in the presence of light. Recovery data following different salt treatments hints at greater role of osmotic constraint than the specific ion effects..