Study On Resistence Ability Of Mosses Under Different Extreme Conditions

In order to understand the dominant species and its water tolerance of aquatic bryophytes in hydro-fluctuation belt of Lengshui River Nature Reserve,Guihzou,China,the contents of Chl a+b,methane dicarboxylic aldehyde?MDA?and soluble sugar,and activities of peroxidase?POD?,superoxide dismutase?SOD?and catalase?CAT?of five dominant bryophytes were determined,and their water tolerances were evaluated.The results showed that there were 11dominant bryophytes in Lengshui River Nature Reserve,in which Rhynchostegium riparioides,Palamocladium euchloron,Hyophila involute,Reimersia inconspicua and Fissidens grandifrons were the most dominant species with average dominance?0.02.With the extension of waterlogging time,the content of Chl a+b in five mosses decreased significantly?P<0.05?,and the contents of soluble sugar and MDA,activities of POD,SOD and CAT increased at first then decreased,showing strong water tolerance in five mosses for long term.The comprehensive evaluation value D of Rhynchostegium riparioides was the highest?0.953?by PCA and subordination function method.Therefore,it was suggested that Rhynchostegium riparioides had strong adaption to waterlogging,could be used as pioneer species in vegetation recover and restoration in hydro-fluctuation belt of Lengshui River.The NaCl tolerance resistance of ten mosses?Philonotis turneriana,Philonotis fontana,Ptychomitrium gardneri,Campylopus umbellatus,Hyophila involute,Anomodon rugelii,Racomitrium anomodontoides,Palamocladium leskeoides,Homalothecium leucodonticaule and Trachypus bicolor?were studied through determination the growth index and physiological index.The methods of principal component analysis?PCA?,subordination function?SF?,correlation analysis and cluster analysis were used for comprehensive evaluation of Nacl tolerance of ten mosses.The result showed that the decrease in LC50 of ten mosses varied from 402.64 mmol?L-1to 501.17mmol?L-1.One growth indexes and five physiological indexes from different mosses showed differences under NaCl stress.Furthermore,two principal components could account for76.64%of the total variance of the data.Based on the values for comprehensive evaluation via the subordinate function?D value?,the Nacl tolerance of ten mosses decreased in the order of P.gardneri,T.bicolor,H.involute,P.leskeoides,H.leucodonticaule,A.rugelii,R.anomodontoides,C.umbellatus,P.turneriara,P.fontana.The result is similar to LC50 and cluster analysis.According to the LC₅₀ and D value of ten mosses,P.gardneri was ranked as the most tolerant to Nacl.The temperature tolerance resistance of three mosses?Rhacomitrum canescens,Taxiphyllum taxirameum and Hyophila involuta?were studied through determination the growth index and physiological index,when these mosses were subjected to the temperature of-80?-20?25?60?and 80?after 5?10?15 and 20 d treatment.The methods of principal component analysis?PCA?,subordination function?SF?,correlation analysis and cluster analysis were used for comprehensive evaluation of temperature tolerance of three mosses.The result showed that based on the values for comprehensive evaluation via the subordinate function?D value?,the high temperature tolerance of three mosses decreased in the order of Taxiphyllum taxirameum,Rhacomitrum canescens and Hyophila involute,the low temperature tolerance of three mosses decreased in the order of Taxiphyllum taxirameum,Hyophila involute and Rhacomitrum canescens.The dry tolerance resistance of five mosses?Ptychomitrium gardneri,Campylopus umbellatus??Hyophila involute,Atrichum angustatum and Haplocladium microphyllum)were studied through determination the growth index and physiological index,when these mosses were subjected to the different treatment time of 5?10?15 and 20 d.The methods of principal component analysis?PCA?,subordination function?SF?,correlation analysis and cluster analysis were used for comprehensive evaluation of temperature tolerance of five mosses.The result showed that based on the values for comprehensive evaluation via the subordinate function?D value?,the dry tolerance of five mosses decreased in the order of Atrichum angustatum,Ptychomitrium gardneri,Hyophila involute,Haplocladium microphyllum and Campylopus umbellatus.The pH tolerance resistance of three mosses?Hyophila involute,Campylopus umbellatus and Ptychomitrium polyphylloides?were studied through determination the physiological index,when these mosses were subjected to the pH of 3,5,7,9 and 11 after 5,10,15 and 20 d treatment.The methods of principal component analysis?PCA?,subordination function?SF?,correlation analysis and cluster analysis were used for comprehensive evaluation of temperature tolerance of three mosses.The result showed that based on the values for comprehensive evaluation via the subordinate function?D value?,the strong pH tolerance of three mosses decreased in the order of Hyophila involute,Ptychomitrium polyphylloides and Campylopus umbellatus.The effect of environment factors on growth and physiological indexes of Hyophila involute were studied.The results show that the factor waterlogging influent most on the growth of mosses.The decision coefficient of environmental factors on soluble sugar is 0.77 and on CAT is 0.58,which will provide the basis for improving environment in different extreme condition.