The Study Of Physiological Adaptability Of Grimmia Pilifera And Racomitrium Japonicum Under Low Temperature Stress

In order to study the effects on Physiological and biochemical indexes of Grimmiapilifera and Rhacomitrum japonicum under low temperature stress and temperature warming,Grimmia pilifera and Racomitrium japonicum were served as materials. In this experimentmethods of artificial control conditions were used, indexes of the two kinds of moss weretreated with4,-20,-40and-80℃low temperature stress, respectively as follows: firstphysiological indexes as malonaldehyde (MDA) content, proline (PRO) content, soluble sugarcontent, soluble protein (SP) content, peroxidase (POD) activity and so on were measured inGrimmia pilifera and Racomitrium japonicum. Secondly in the artificial control experiment,under low temperature stress (4,-20,-40,-80℃) then the temperaturerearmed to25℃c ondition, chlorophyll fluorescence parameters and physiological indexes ofGrimmiapilifera and Rhacomitrum japonicum were determined. The results are as follows:1. When the two kinds of moss treated with4,-20,-40and-80℃low temperature stress,the proline, soluble sugar, MDA content and peroxidase activity increased comparing with thecontrol as the temperature declined, the soluble protein content rapidly rose up at4℃, butdecreased at temperature of-20,-40, and-80℃,the soluble protein content fell firstly within30-day stress, then rose up fast with stress time increasing.2. In temperature-controlled experiments, as temperature rewarmed to25℃condition,proline, soluble sμgar, soluble protein content and peroxidase activity of the two kinds ofmoss gradually decreased. But they were significantly higher than the control; the MDAcontent fell down firstly, and significantly lower than the control after30days.3. During4,-20,-40and-80℃low temperature stresstreatments. Changes of theYield,ETR, Fv/Fm, Fv`/Fm`were consistent, they declined firstly and then increased, but stilllower than the condition before treated with stress; the NPQ gradually increased, its wassignificantly higher than that before the stress treatment.4. In temperature-controlled experiments, after temperature rewarmed to25℃condition,with the rewarming time proceeding, Yield, ETR of the two kinds of moss inereasedgradually, they were significantly higher than that before stress; the Fv/Fm and Fv`/Fm`increased firstly and then declined; the NPQ declined gradually. Combined with the experimental results, it showed that there is certain relevancybetween changes of osmotic regulation substances, MDA content and peroxidase activity inGrimmia pilifera and Racomitrium japonicum and cold resistence. In the process of differentdegrees of low temperature stress, Both the mosses can prevent cell membrane peroxidationthroμgh the accumulation of osmotic regulation substances to maintain the integrity of the cellmembrane, and ensure the normal physiological and biochemical reaction on the cellmembrane. After the temperature rewarmed to25℃,osmotic regulation substances andphotosynthetic characteristics of the two kinds of moss can be restore. In conclusion,Grimmia pilifera and Racomitrium japonicum can be adapted to the cold throμgh the osmoticregulation substances and photosynthetic characteristics adjustment...