Variation In Endogenous Hormone And Phenolic Compounds In Poplar Leaves During The Drop In Climatic Temperature In Late Autumn

Poplar is an important afforested and greening arbor in northern region of China,and the freezing damage is also a main problem in forestry production and afforestation.In the present study,using Populusr'Zhonglin Sanbei 1' and Populus albaxberolinsis as study materials,the variation in contents of photosynthesis pigments,soluble sugar,soluble protein,endogenous hormone,flavonoid,total phenol and rutin were determined during the drop in climatic temperature in late autumn;the relationships between all indexes and the changes of temperature were analyzed;and the potential functions of these compositions on antitemperature stress were preliminarily discussed.During the drop in climatic temperature in late autumn,the variation in chlorophyll, chlorophyll a and chlorophyll b contents were in accordance with the change of climatic temperature,namely they decreased with the decrease of temperature,and had significant positive correlations to temperature.Carotenoid content weakly related to temperature decreasing;whereas significant negative correlation between the value of caronoid/chlorophyll and the change of temperature was showed.In a whole,the content of photosynthesis pigments in leaves of P.alba×berolinsis was higher then P.×'Zhonglin Sanbei 1'.The regulation in soluble sugar in leaves of P.×'Zhonglin Sanbei 1' was similar as that in P.alba xberolinsis,and had a significant negative relationship with the change of temperature, that the content increased as the temperature decreased.The variation in soluble protein content little related to the change of temperature.Flavonoid content in P.×'Zhonglin Sanbei 1' and P.albaxberolinsis leaves increased as temperature decreased,and the variation in total phenol content had the same trend.11 kinds of compounds out of 15 phenol compounds were detected,in which 7 compounds were existed in both trees.Rutin,was a higher abundant phenol compound in poplar leaves,and its content in P.×'Zhonglin Sanbei 1'was much higher than that in P.albaxberolinsis,which might relate to the better ability in freezing tolerance than P.×'Zhonglin Sanbei 1'.The contents of ABA,IAA and ZR in P.×'Zhonglin Sanbei 1' and P.alba×berolinsis leaves had the similar regulations during the process of temperature drop,which increased when the temperature dropped and showed negative correlations to temperature.GA₃ contents in both poplar leaves were also similar,which was higher in the mid-sampling dates whereas they were at a lower level in the other days.Furthermore,ABA/GA₃ also increased as temperature dropped,was remarkable negatively correlated to air temperature.