高浓度CO_2对热胁迫条件下高羊茅生长和抗氧化系统的影响

Effects of elevated carbon dioxide concentration on the growth and antioxidant system in tall fescue under heat stress

大气CO_2浓度及温度逐年上升是当前全球范围内主要的两大气候特征,但不断升高的大气CO_2浓度可以缓解高温对植物生长发育带来的负面影响。为了探究高浓度CO_2在多年生禾草生长和抗氧化系统方面对热胁迫的响应,本试验以高羊茅(Festuca arundinacea cv.‘Barlexas’)为材料,进行CO_2[当前浓度(400μmol/mol)和高浓度(800μmol/mol)]和温度[(最适生长温度(25/20℃)和热胁迫温度(35/30℃)]处理。结果表明,高温导致高羊茅的生长速率(Gr)、净光合速率(Pn)、光化学效率(Fv/Fm)、绿叶数、活性氧清除物质[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)]活性等显著下降,叶片黄绿比、电解质渗漏率(EL)、丙二醛(MDA)、活性氧[过氧化氢(H_2O_2)、超氧阴离子(O_2^-·)]显著上升;热胁迫处理28d时,高浓度CO_2较正常CO_2浓度使细胞膜稳定性增强(EL、MDA分别降低72%和39%),光合能力提高(Pn、Fv/Fm、绿叶数分别升高174%、17%和165%),活性氧积累减少(H_2O_2、O_2^-·含量分别下降46%和31%)。以上结果说明:高浓度CO_2通过提高高羊茅在热胁迫下的光合能力,维持细胞膜的稳定以及减少体内活性氧的积累减弱了热胁迫对植株的伤害,从而提高了高羊茅的抗热性。

The gradual increases in the atmospheric C02 concentration and temperature are the two primary characteristics of global climate change. However, the rising atmospheric C0 2 concentration could alleviate the negative effects of heat stress. Therefore, the aim of this study was to explore the mitigating effects of elevated C02 on the growth and antioxidant system a perennial grass under heat stress. Tall fescue （Festuca arundina- cea cv. 4Barlexas？） was exposed to either ambient C02 concentration （400 j ^mol/mol） or elevated C0 2 concen-tration （800 jLtmol/mol） under optimal growth temperature （25/15 °C day/night） or elevated temperature （35/ 25 °C day/night） conditions. After 28 days of the experimental treatment, heat stress caused a significant re-duction in relative growth rate （RGR） , leaf net photosynthetic rate （Pn） , number of green leaves, antioxidantenzyme activities [（superoxide d i s m u t a s e, （SOD）,catalase （CAT）,peroxidase （POD ） , a n d ascorbate peroxi-dase （APX ）] , as well as an increase in electrolyte leakage （EL ） , a n d the contents of malondialdehyde （MDA ） and reactive oxygen species （ROS ） （H 202 a n d 02- ）. Elevated C 0 2 mitigated these negative effects of heat stress in tall fescue. Compared with plants g r o w n under heat stress a n d a m b i e n t C 0 2,those g r o w n under heat stress and elevated C 02 had lower leaf EL a n d MDA contents （72 % a n d 3 9 % l o w e r , respectively）; the P n , F v/ Fm , and number of green leaves w e r e increased b y 1. 74-fold, 1 7 % , a n d 1. 65-fold, respectively; a n d the R O S contents were significantly lower （H 202 a n d 02- contents decreased b y 4 6 % a n d 31 % , respectively）. T h e s e results demonstrated that elevated C 02 can i m p r o v e the heat tolerance of tall fescue t h r o u g h increased p h o t o-synthetic capacity, cellular membrane stability, a n d decreased ROS accumulation.