Comparative Study Of Salinity Stress On Physiological Effect In Two Limonium Mill

Soil salinization is one of the major abiotic stresses which constraints plant growth and development.Salt-tolerance of plant is complex reaction process involving many factors,such as physiology and biochemistry.Limonium aureum (Linn.)Hill and Limonium gmelinii(Willd.)Kuntze are with important economic value recretohalophyte capable of growing under extreme condition,from very dry environments to highly saline soils.The important ecological effects of two Limonium Mill are in virescencing salty soil and improving environmental performance. Therefore,research on the salt-tolerance mechanism of two Limonium Mill has the significant theoretical value for the development and utilization of anti-stress plant resource and reconstructing weak ecological environment in Northwest China.The changes of physiological indexes,such as seed germination,chlorophyll, solution protein caused by different NaCI concentration or 150 mrnol.L-1 NaC1 for 12,24,48 h treatment were investigated in two species of Limonium Mill,Limonium aureum(Linn.)Hill and Limonium gmelinii(Willd.)Kuntze.The mechanism of salt tolerance was expatiated by investigating and comparing two Limonium Mill.The main results were as following:NaCl treatment caused a pronounced inhibition in the seed germination ratio and a decrease in seed germination index of two Limonium Mill in a concentrate-dependent manner.The growth ofLimonium aureum(Linn.)Hill root and the sprout of Limonium gmelinii(Willd.)Kuntze were increased under low NaC1,but the seedlings of two Limonium Mill were inhibited under high NaC1 treatment.Compared to the control,the amount of chlorophyll a,chlorophyll b and total chlorophyll in two Limonium Mill decrease under treatments of 50,150 and 300 mmol.L1 NaC1,but that of H₂O₂ and MDA increase.The activities of SOD and APX were increased in two Limonium Mill leaves exposed to NaC1 treatment for 48 h.Similar changes of physiological indexes were observed in two Limonium Mill after 12,24 and 48 h under 150 mmol.L^-1NaCl treatment.The soluble protein content was enhanced in two Limonium Mill leaves under low NaCl concentration,but decreased under high NaC1 concentration.Compared to the control,the soluble protein content in leaves increased 109.89%,118.24%and 146.00%in L.aureum(Linn.)Hill,and 105.42%,111.48%and 96.36%in L.gmelinii (Willd.)Kuntze under 150mmol/L NaCI treatment for 12,24 and 48 h,respectively. Investigation of soluble protein content by SDS-PAGE showed that a significant increase of the amount of soluble protein was induced in leaves of L.aurcum (Linn.)Hill seedlings after NaCI treatment compared with the control.But an increase after 12 and 24 h,a decrease after 48 h in L.gmelinii(Willd.)Kuntze seedlings were observed;In addition,NaC1 treatment caused a stronger inhibition of seed germination and chlorophyll content in L.gmelinii(Willd.)Kuntze than that in L.aureum (Linn.)Hill,and a higher enhancement of the amount of H₂O₂ and MDA in L.gmelinii (WilM.)Kuntze.These results indicated that salinity tolerance of L.aureum(Linn.)Hill was stronger than that of L.gmelinii(Willd.)Kuntze.