淹渍胁迫对柑橘若干生理特性的影响

Effects of Waterlogging Stress on Some Physiological Characteristics of Citrus

为探明淹渍胁迫下柑橘树体生理响应机制,给柑橘防涝减灾提供理论依据,本试验采用三年生枳砧‘大分四号’温州蜜柑在夏季进行淹渍4、6、8、10 d处理,分析夏季淹渍胁迫对其外观形态、净光合速率、脯氨酸(Pro)含量、丙二醛(MDA)含量、过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性、根系解剖结构以及根系养分含量等的影响差异。结果表明,柑橘在淹渍后叶片黄化、光合速率下降,且随着淹渍时间的延长出现干枯落叶。淹渍处理后柑橘叶片Pro含量、MDA含量、POD活性均显著高于对照(CK),淹渍10 d时Pro含量较CK增加19.81%,MDA含量较CK增加83.29%,POD活性较CK增加1.08倍;SOD活性自淹渍6 d开始低于CK。对照组CK柑橘根细胞结构清晰,表皮细胞完整,皮层薄壁细胞排列紧密,细胞间隙小,无明显气腔;淹渍处理组(WL)根系腐烂发臭,韧皮部脱落,根系表皮细胞离解。淹渍胁迫会抑制柑橘根系对K元素的吸收,淹渍处理10 d根系中的K含量较CK减少61%。综上,淹渍胁迫影响柑橘生长发育,三年生柑橘耐高温淹渍的能力为4~6 d,进一步持续淹渍胁迫导致叶片黄化脱落、净光合速率降低、抗逆性物质含量上升,根系韧皮部坏死脱落、吸收养分能力下降。植株SOD活性降低与柑橘淹渍胁迫密切相关。

This study aims to clear physiological changes of citrus under waterlogging and provide theory basis for waterlogging defense.Three-year old’Oita4’(Citrus unshiu Marc.)grafted on trifoliate orange was adopted.Plants were treated with waterlogging stress in summer for 4,6,8,10 days,and then plant morphology,net photosynthetic rate,proline content(Pro),malondialdehyde(MDA)content,peroxidase(POD)activity,superoxide dismutase(SOD)activity,root anatomical structure and root nutrient content were analyzed.The results showed that leaves chlorosis even to defoliation happened with waterlogging time extension,and photosynthetic rate decreased after waterlogging as well.Pro content,MDA content and POD activity in citrus leaves were significantly higher than them in control group(CK)after waterlogging.Relative to CK,Pro content,MDA content and POD activity increased 19.81%,83.29%and 1.08 times respectively after 10 days of waterlogging.SOD activity was lower than that in control after 6 days of waterlogging.Root cells in CK plants showed clear structure and arranged well totally,in which epidemic cells were integrated and cortical parenchyma cells arranged closely without obvious air cavity.But in treatment plant(WL),roots rotted smelly with abnormal color epidemic cells in waterlogged root dissociated leading to phloem shed.Waterlogging stress inhibited K absorption in citrus root.Potassium content decreased to 61%of that in CK after 10 days waterlogging.Above all,waterlogging stress effects of citrus development.Waterlogging,for 4~6 days under high temperature in summer should be tolerant for citrus,and then chlorosis,defoliation,net photosynthetic rate decrease,stress-resistant substances increase,root rotting and nutrient absorption loss will happen with further waterlogging stress.Decrease of plant SOD activity is closely related to waterlogging stress of Citrus.