苗期玉米叶片碳氮平衡与干旱诱导的叶片衰老之关系

为了探究干旱诱导的碳氮平衡破坏与干旱诱导的叶片衰老之间的关系,该实验以8个在干旱胁迫下叶片衰老进程有明显差异的玉米品种为实验材料,采用PEG模拟干旱处理,通过测定光合速率、叶绿素含量和叶绿素荧光参数等叶片衰老指标以及非结构性碳水化合物(可溶性糖、淀粉)和全氮含量等变化,分析玉米中干旱诱导的叶片衰老与叶片中碳氮平衡(碳氮比)之间的关系。结果显示:(1)干旱胁迫下,8个玉米品种叶片净光合速率受到严重抑制,Fv/Fm大幅下降,叶绿素含量显著降低,说明干旱诱导了玉米叶片的衰老;(2)干旱诱导玉米叶片衰老的同时,8个玉米品种的叶片中可溶性糖含量显著升高,淀粉含量小幅上升,全氮含量大幅降低,碳氮比显著升高,碳氮平衡遭到了破坏;(3)8个玉米品种叶片的叶绿素含量与非结构性碳水化合物含量以及碳氮比呈极显著负相关关系,与全氮含量呈极显著正相关关系。因此,碳氮代谢与干旱诱导的叶片衰老紧密联系,碳氮平衡可能参与了干旱诱导的叶片衰老调控。

Carbon/Nitrogen Balance Associate with Drought induced Leaf Senescence in Maize (Zea mays) Seedling

To investigate the association between drought induced carbon/nitrogen imbalance and leaf senescence,we treated eight maize varieties in leaf senescence progress under drought stress with PEG to mimic the drought stress.Leaf senescence symptoms,such as photosynthesis,photosystem II photochemistry efficiency (F_v/F_m) and chlorophyll content,and the non structural carbohydrates (soluble sugars,starch) content and nitrogen content were determined.Then,the correlation between drought induced leaf senescence and carbon/nitrogen imbalance (C/N ratio) was analyzed.Our results showed that:(1)the net photosynthetic of eight maize varieties were severely suppressed,F_v/F_m has fallen dramatically and chlorophyll content decreased significantly,which indicated that drought induced maize leaf senescence.(2)Drought stress induced the maize leaf senescence accompanied with the accumulation of soluble sugar content,slightly increased starch content,decreased of total nitrogen content and increased significantly of C/N ratio,carbon and nitrogen balance were damaged.(3)Both the non structural carbohydrates content and carbon/nitrogen ratio showed a significant negative correlation with chlorophyll content,and there was a significant positive correlation between total nitrogen content and chlorophyll content.Therefore,carbon and nitrogen metabolisms were tightly associated with drought induced leaf senescence,and the carbon/nitrogen balance may involve in the regulation of drought induced leaf senescence.