Effects of Photosynthetic Performance of Cold Resistant Differential Steno-taphrum secundatum on Low Temperature Treatment
Two strains of Stenotaphrum secundatum,which were cold resistant material S13 and sensitive material S55 based on previous studies,were analyzed on the differences in photosynthesis at 0,3,7 and 14 d through simu-lated low temperature treatment.The results showed that the net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)of the two materials decreased significantly with the extension of cold stress time,while the intercellular CO2 concentration(Ci)rised after the first drop,indicating that the Pn of S.secundatum decreased due to stomatal limitation factors in the early stage of cold stress,but not due to stomatal factors in the later stage.The chlorophyll content(Chl),carotenoids content(Car)and chlorophyll fluorescence parameters(Fv/Fm)showed a gradual decreasing trend,which indicated that S.secundatum was photoinhibition.After 3 days of low tempera-ture treatment,the Chl,Car and Fv/Fm of S13 were significantly higher than those of S55,but there was no signifi-cant difference in photosynthetic parameters.After 7 days of low temperature treatment,Pn,Gs,Tr,Chl,Car and Fv/Fm of S13 were significantly higher than those of S5 5,and Ci was lower than that of S5 5.After 14 days of low tem-perature treatment,Pn,Chl and Car of S13 were still significantly higher than those of S55,Ci was lower than that of S55,and there was no significant difference in other indexes.This experiment was conducted to study the ef-fects of low temperature treatment on photosynthetic characteristics of different S.secundatum,so as to provide reference for the cold-resistant cultivation and breeding of S.secundatum.
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