土壤自然干旱胁迫对甘蔗幼苗根系保护酶系统的影响

Impact of natural soil drought stress on protective enzyme system in root system of sugarcane seedlings

【目的】研究干旱胁迫对甘蔗苗期根系保护酶系统及相关指标的影响,探讨甘蔗苗期根系对干旱胁迫的应答机制。【方法】以新台糖22号为材料,在甘蔗苗期进行土壤自然干旱胁迫,测定甘蔗根系保护酶系统及质膜过氧化产物相关指标的变化,并进行相关性分析。【结果】随着干旱胁迫程度的加强,根系中可溶性蛋白质、丙二醛(MDA)、过氧化氢(H2O2)含量逐渐增加,细胞膜脂过氧化保护酶系统的酶活性均呈先升后降的趋势,干旱胁迫处理15d后SOD和POD活性达到峰值然后降低,CAT活性于11d到达峰值后下降。甘蔗苗期根系保护酶活性与膜脂过氧化作用呈显著或极显著正相关。【结论】甘蔗根系保护酶系统的干旱胁迫响应机制为:轻度干旱与中度干旱时表现为积极应对,重度干旱时则为被动忍耐。根系保护酶系统与甘蔗抗旱性的关系密切。

[Objective]The present experiment was conducted to study the effects of natural drought stress on protective enzyme system and related indicators in order to explore the mechanism of sugarcane seedling roots responding to drought stress.[Method]Using ROC 22 as test material,protective enzyme system and plasmalemma peroxidates related indexes of root system were detected under natural drought stress at the sugarcane seedling stage,and their correlations were analyzed.[Result]With the intensification of drought stress,the content of soluble protein（SP）,malondialdehyde（MDA）,and hydrogen peroxide（H2O2） showed gradual increases,while the activities of SOD and POD increased at first but then decreased afterwards.After continuous drought conditions,the activities of SOD and POD reached the highest after 15 days but decreased afterwards.Similarly,the activity of CAT reached its maximum on the 11th day but decreased afterwards.The protective enzyme system in root was significantly positively correlated with cell membrane-lipid peroxidation.[Conclusion]The protective enzyme system in sugarcane roots responded well to mild or moderate drought stress;on the other hand,the protective enzyme system responded poor to severe drought.Protective enzyme system of roots was closely related to the drought resistance of sugarcane;this research data could be advantageously used in drought resistance identification.