干旱胁迫下Si对甘蔗叶片相对水含量和抗氧化物酶活性的影响

【目的】研究干旱胁迫下不同Si（硅）水平对不同耐旱性甘蔗品种的抗氧化物酶活性的影响,为探索Si提高甘蔗抗旱性的生理基础提供依据。【方法】采用水培法,设置3个施Si浓度（0、0.2、1.7 mmol/L）,经不同PEG-6000胁迫时间（0、18、26、30、40 h）后,测定两个耐旱性甘蔗品种（ROC16和ROC22）甘蔗叶片的相对水含量（RWC）及超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）等保护酶活性。【结果】与对照处理（Si浓度0 mmol/L,PEC-6000胁迫时间0 h）相比,随着胁迫时间的延长不同浓度Si处理的叶片RWC持续下降,POD活性先降后升,CAT活性先升后降,SOD活性则表现为先降后升再降的抛物线式变化趋势。ROC22的抗氧化物酶活性均高于ROC16。【结论】施Si能提高甘蔗叶片RWC及SOD、POD和CAT的活性,且高Si浓度（1.7 mmol/L）比低Si浓度（0.2 mmol/L）效果好。

Effects of silicon on leaf RWC and activities of defense enzymes in sugarcane under drought stress

【Objective】The effects of exogenous silicon on leaf RWC and antioxidative defenses under drought stress were studied to provide theoretical references for using silicon to improve drought resistance of sugarcane. 【Method】Hydroponics was employed and three silicon levels（0, 0.2, 1.7 mmol/L） were set to investigate RWC, SOD, POD and CAT of two sugarcane varieties at different time（0, 18, 26, 30, 40 h） after PEG treatment. 【Result】The results showed that compared with the control（Si concentration： 0mmol/L, PEG-6000 stress duration： 0h）, leaf RWC decreased with the duration of stress. The activity of POD decreased at the beginning and increased later,but the activity of CAT increased and then declined, which was in contrary with that of POD. The activity of SOD went down, up and then down again.The activities of SOD, POD and CAT in drought-tolerant ROC22 were higher than those of drought-suscepitable ROC16. 【 Conclusion 】 The application of silicon can obviously increase leaf RWC and the activities of SOD, POD and CAT in both varieties. Moreover the effect of high Si concentration（1.7 mmol/L） is better than that of low Si concentration（0.2 mmol/L）.