| Two wheat varieties Jimai22and Shannong17were used to study the changes ofantioxidant enzymes and α-amylase activity, soluble sugar and endogenous hormone contentunder the conditions of different temperatures and simulated drought use PEG during seedgermination of wheat. That aimed at exploring the influence of different temperatures anddrought condition on seed germination. The obtained results are as follows:1The antioxidant enzyme activity changed regularly during wheat seed germinationunder different temperature. The result showed that the activity of SOD and POD increasedalong with the increased temperature. However, the activity of POD showed differentregularity under different germination temperature. All of these three enzyme activity werelower under10℃, and the changes are not obviously. The the activity of SOD and PODincreased rapidly after48h under15℃, however SOD activity increased homogeneousenhance during the whole germination process. Under20℃, POD activity increased rapidlyafter36h germination, CAT increased rapidly to the maximum after48h germination andthen showed a downward trend. under25℃, After germinated for24h, POD activityincreased rapidly which was the highest among the four temperature treatment, and CATactivity increase to the maximum after germinated for24h and then showed a downwardtrend.2The activity of POD, CAT, SOD during seed germination exhibited differentcharacteristics with the different levels of drought under the conditions of simulated drought.POD activity treated12~36h by20%PEG-6000changed little but rised rapidly after36htreatment; CAT activity treated12~42h by20%PEG-6000grew slowly but rised rapidly after42h treatment; SOD activity treated12~24h by20%PEG-6000increased rapidly butascensional range became smaller after24h treatment.3The α-amylase activity increased at first and then reduced under the conditions of25℃and20℃. Thereinto it changes largely under the condition of25℃. The α-amylase activity ofthe two varieties are highest at the fourth day of germination. And the peak of Jimai22theShannong17appeared at the fifth and sixth day of germination respectively under conditionof20℃. The trend of15℃and10℃treatment were the same. The soluble sugar content ofthe two varieties showed a single peak curve under three temperature treatment. But the time to reach peak delayed with the decreasing temperature.The α-amylase and antioxidant enzyme activity of the two varieties treated by20%PEG-6000had similar trends, but the activity of Shannong17which germinated sixth andseventh day was higher than that of normal germination under the same temperature. Solublesugar content showed a single peak curve. Both the two varieties peaked at48h aftergermination.4The endogenous hormone levels of the two varieties changed greatly during seedgermination. The GA content was gradually increased with the extension of the germinationtime, but the increasing speed was different at different temperatures. The higher thetemperature of germination, the faster the GA content increasing, and the faster the speed forseed germination. The GA content will gradually decline after germination completed. Theseeds contain a certain amount of ABA before germination to keep the seeds in a dormantstate. And the ABA content began to decline in the seed after germination. The higher thegermination temperature, ABA content decreased the sooner. In the end, the rise of GAcontent and the decline of ABA content jointly promote seed germination. IAA content in theseed was gradually increased during germination. The higher the germination temperature, thefaster the IAA content increased. After2days germination gradually stabilized at25℃.The GA content in the seed under20%PEG-6000simulated drought conditions waslower than that with germinated normally at the same temperature. The difference of ABAcontent was not too obvious after analysis of variance. And IAA content under simulateddrought conditions was lower than that germinated under normal condition. |
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