臭氧胁迫下遮荫对孕穗期冬小麦叶片光合系统的影响

摘要

To assess the gas exchange parameters,chlorophyll,accumulation of assimilation products and anti-oxidation system of winter wheat (Triticum aestivuml Yangmail3) under elevated O3 and reduced solar irradiance,five field experiments were conducted inside open-top-chambers (OTC).Five treatments (CK,T1,T2,T3 and T4) were designed as follows:CK consisted of nature O3concentration and nature solar irradiance,T1 of 100nL·L-1O3 concentration and 40％ of nature solar irradiance,T2 of 100nL·L-1O3 concentration and 60％ of nature solar irradiance,T3 of 100nL· L-1 03 concentration and 80％ of nature solar irradiance,T4 of 100nL·L-1 and no shading.The results showed that O3 stress caused intercellular CO2 concentration increasing,leaf photosynthetic rate,chlorophyll (chl) and carotenoid (Car) decreasing;O3 and shading composite treatment accelerated the net photosynthetic rate declining,while it could relieve chlorophyll (chl) and carotenoid (Car) falling.The photosynthetic rate descending were caused by non-stomatal factors under the two kinds of circumstances.O3 stress significantly increased leaf soluble sugar and total free amino acids,the soluble protein was significantly reduced;Under O3 and shading composite treatment,leaf soluble sugar no longer increased,and soluble sugar and soluble protein content declined,while the total free amino acid content continues to increase as the shading intensified.Carbon metabolism was planted major supersession under O3 stress,adding the weakened radiation to ozone stress changed the metabolism of plants,the main metabolism converted Carbon into nitrogen metabolism.O3 stress increased leaves malondialdehyde content (MDA),catalase (CAT),peroxidase (POD),superoxide dismutase (SOD) activity;Under O3 and shading composite treatments,leaves MDA decreased significantly,CAT,POD,SOD content was significantly higher,it indicated that increased antioxidant enzymes of plant could not completely eliminate excessive reactive oxygen species,leading to accumulation of reactive oxygen species,which resulted in the increase of membrane permeability under Os stress,reduced solar irradiance relieved the damage of ozone on plants in a certain extent.%在大田试验条件下,基于开顶式气室和遮荫网装置,设置CK(自然臭氧和太阳辐射)、T1(100nL·L-1臭氧+ 40％ CK太阳辐射)、T2(100nL·L-1臭氧+ 60％ CK太阳辐射)、T3(100nL·L-1臭氧+ 80％ CK太阳辐射)、T4(100nL·L-1臭氧+ 100％ CK太阳辐射)5个处理组,对孕穗期冬小麦叶片气体交换参数、叶绿素(chl)、抗氧化系统酶活性等进行测定.结果表明,(1)臭氧胁迫造成冬小麦叶片光合速率下降、胞间CO2浓度增加,叶绿素(chl)、类胡萝卜素(Car)含量减少;臭氧+遮荫处理后,叶片净光合速率加速下降,但可缓解叶绿素含量、Car含量的下降.说明两种情况下叶片光合速率的下降都是由非气孔因素引起的.(2)臭氧胁迫使叶片中的可溶性糖显著升高、可溶性蛋白明显降低、总游离氨基酸明显升高;臭氧+遮荫处理后,叶片中的可溶性糖不再增加,并随着遮荫程度的加重而下降,可溶性蛋白含量继续下降而总游离氨基酸含量继续增加.说明植株代谢从臭氧胁迫下的碳代谢为主转为臭氧+遮荫下的氮代谢为主.(3)臭氧胁迫使叶片中丙二醛(MDA)含量、过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性均升高;臭氧+遮荫处理后,叶片中MDA明显下降,CAT、POD、SOD含量均明显升高,说明高浓度臭氧环境下,叶片通过增强抗氧化酶活性以提高活性氧自由基(ROS)的清除能力,但由于不能完全清除,造成膜质过氧化程度加剧从而加速植株衰老,太阳辐射减弱会在一定程度上减缓臭氧对植株的伤害.