| The area of tea gardens in northern and southern shores of the Yangtze River continues to expand in recent years,the extreme cold of late autumn to early spring and the "late spring" unexpected,so that large tea gardens suffer frost damage,resulting in decreased yield and quality of tea,winter frost become serious natural disasters among tea area.In order to study the response of osmotic adjustment substances and protective enzyme to low temperature,and the influence of low temperature freezing injury on tea volatiles.The study measured the changes of tea osmotic adjustment substances during the winter in two consecutive years,and analyzed activities of tea protective enzymes in tea plantation with different anti freezing measures from autumn to next spring,and researched the quality and quantity changes of volatile components in freezing frost tea samples,the results as follow:(1)(1)Continuous two years,the test during the winter,the temperature gradually decreased,and sustained low temperatur,the soluble sugar contents in fresh tea leaves of the two cultivars increased continuingly,negatively correlated with the 10-day average air temperature;the proline contents increased first and then kept at a high level,also negatively correlated with the 10-day average air temperature;while the free amino acid contents dropped first and then stayed at a low level,which was positively correlated with the 10-day average air temperature;(2)During the two spring seasons,as air temperature increased gradually,the soluble sugar contents lessened,while the proline and the free amino acid contents appeared to increase;(3)During the two winter seasons,the responsiveness of cultivar Pingyangtezao to the low temperatures was greater than that of cultivar Zhongcha 102.(2)(1)As suffered low temperature stress,the response degree of CAT enzyme to low temperature was less sensitived than POD enzyme,POD enzyme activity significantly correlated with temperature.It was proved that POD enzyme could be used as an index of cold resistance of tea plant.(2)When it comes to encounter with low temperature stress between 0 ℃ to 10 ℃,the enzyme activity in anti frost fan tea garden was significantly higher than that in common tea garden and tea-tree intercropping plantations.When faced with adversity low temperature under 0 ℃,in short time,the enzyme activity in tea-tree intercropping plantations can reach the level of anti frost fan tea garden.As the low temperature under 0℃ last for three months,the enzyme activity in anti frost fan tea garden was highest,the enzyme activity in common tea garden was the worst,and a significant difference was found in enzyme activity of three kinds of tea plantations.After a severe winter,meet “late spring coldness”,the enzyme activity in three kinds of tea garden increased rapidly,and there was no significant difference.(3)Collected several number tea shoots with one bud three leaves,under laboratory conditions,subjected to different temperature and different time,SDE-GCMS method was used to detect the volatile component,compared with the control,found that: the content and proportion of alcohols in cold tea samples decreased,the total content and total number of volatile organic compounds were lower than that of the control,and under the same temperature treated samples,the total content and total numbe of volatile substances decreased with prolonging of treatment time.Analysis shows that tea plants resisted against the frost by means of the various osmotic substances and enzymes,and the frost resistance ability differed in the different cultivars.After frosted,the contents and the ratios of volatile substances of tea plants altered,which affected tea quality. |
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