Study On Characteristic Of Salt-tolerance At Different Growth Stages Of Phrgmintes Australis

Phrgmintes australis(common reed) is the main constructive species of wetland emergent plant communities, widely spreads in freshwater wetlands, even in coastal wetlands and inland saline wetlands that with higher salinity. Phrgmintes australis is an important tool plant for its ability of strong resistance, daptability and rapid propagation. We have made some achicevements in using Phrgmintes australis as a tool plant to restore the coastal wetland and inland saline-alkaline wetland. However, the high soil salinity is has a negative influence on the restoration of coastal beaches and inland saline wetland. At present, a lot of researches focused on the physio-ecological responses of Phrgmintes australis to the environmental factors and or different management methods in the output of the reed, only a few researches focus on the characteristic of salt-tolerance at different growth stages of phrgmintes australis. Four cultivation patterns are widely used in Phrgmintes australis transplantation, including seed propagation, seeding cultivation, rhizome cultivation, plant transplantation and aerial stem cultivation. This article takes four growth stages of reed(seed, adult plant, young plant, rhizome) as the analysis objects. Research the physio-ecological responses of reed under different salinity treatment from the aspects of growth characteristics, photosynthesis, osmotic adjustment substances, antioxidant enzymes, etc. Discuss salt tolerance mechanisms and suitable salinity range for reed growing upon three stages(adult, seedling and germination).The main findings were as follows:(1) Salinity obviously inhibited seed germination of Phrgmintes australis.It has a trend of decreased germination percentage and rate of germination with the increase of salinity levels. When salt concentration was 20‰,the seeds were not burgeoned. Germination rate, germination potential and germination index were reduced quickly when salinity is 8‰.Salinity also inhibited the seedling, when salt concentration was 6‰,the decrease of the height was very significant. Therefore, the soil salinity should be lower than 6‰.(2) Salinity obviously inhibited the growth of Phrgmintes australis. Results show the limits of salt-resistant of adult plant is 40‰,for the young plant is 30‰,and for the rhizome is 25‰.Salinity obviously inhibited the height, leaf length, leaf width, leaf area, biomass and tiller number. However, diameter was no significant difference. The salt resistance of adult plant of Phrgmintes australis is significantly higher than young plant and rhizome.(3) Salinity obviously inhibited photosynthesis of Phrgmintes australis. The net leaf photosynthetic rate, stomatal conductance, intercellular C02 concentration and transpiration rate were significantly reduced, The higher the concentration of salt treatment, the greater the decrease.(4) Under salt stress, the MDA, soluble sugars content and praline were increased, the soluble protein content were reduced.SOD and POD of adult and young plant had the same change trend on the basic, it can conclude first increase then decline. The increase of SOD enzymatic activity of rhizome was very significant when salinity is 5‰,and then decreased, POD enzymatic activity of rhizome was decreased with the increase of salinity levels.(5) This article discussed suitable salinity range of reed adult,seedling and germination which combined with physiological and ecological indicators,including plant height,biomass, leaf area, etc. Moreover,the suitable salinity value for adult plant, young plant, germination growth were less than 20‰,15‰,10‰ respectively. Rhizome could hardly sprout when salinity exceeds 25‰ and seedling rate decreased prominently when salinity value over 10‰.Therefore,reed rhizome was suitable for transplanting under 10‰ salinity value and need to control the water level.