黑麦草属2草种对臭氧浓度倍增的生理响应

以一年生黑麦草(Lolium multiflorum)和多年生黑麦草(Lolium perenne)为实验材料,利用开顶箱(OTC)模拟法,研究了这2种黑麦草在正常大气O₃(CK,40 nmol·mol^-1)及其浓度倍增(80,120,160 nmol·mol^-1)条件下叶片生理生态指标的变化规律。结果表明:随着O₃胁迫加剧,2种黑麦草呈现出较为类似的伤害症状,但一年生黑麦草在熏蒸前期先出现黄褐色点状伤斑。与对照相比,高浓度O₃均显著提高了一年和多年生黑麦草叶片丙二醛(MDA)含量(分别提高21.7%和28.1%)及SOD活性(分别提高71.2%和129.8%)与POD活性(分别提高32.3%和57%)(P<0.05);高浓度O₃显著降低了2种黑麦草叶片的净光合速率(P_n)(分别降低51.6%,57.5%)、气孔导度(G_s)(分别降低45%,52.5%)、最大光化学效率(F_v/F_m)(分别降低6.4%,5.5%)、实际光化学效率(Φ_PSⅡ)(分别降低18.9%,10.5%)(P<0.05)。多年生比一年生黑麦草更耐臭氧,主要原因在于臭氧浓度不超过120 nmol·mol^-1的胁迫下,多年生黑麦草具有更高的抗氧化能力以及适应臭氧的气孔调节能力,从而减缓了臭氧对其的伤害。本研究旨在为植物对臭氧逆境的适应机理研究以及全球气候变化背景下城市草坪植物筛选及其应用提供科学依据。

Physiological Responses of Two Lolium Varieties to the Enhancements of Tropospheric O3 Concentration

The variations of the physiological indexes of annual Lolium multiflorum and perennial Lolium perenne leaves under different O₃ concentrations(80, 120, 160 nmol·mol^-1)were investigated using open top chambers(OTCs). The results showed that two Lolium varieties had the similar injury symptoms induced by O₃ stress, while brown injury spots appeared on Lolium multiflorum earlier. Elevating O₃ concentration, the content of malondialdehyde(MDA) significantly increased by 21.7% and 28.1%; the activities of superoxide dismutase(SOD) increased by 71.2% and 129.8%; peroxidase(POD) increased by 32.3% and 57%, whereas net photosynthetic rate(P_n) decreased by 51.6% and 57.5%; stomatal conductance(G_s) decreased by 45% and 52.5%; maximum photochemical efficiency(F_v/F_m) decreased by 6.4% and 5.5% and the actual photochemical efficiency(Φ_PSⅡ) decreased by 18.9% and 10.5% in the leaves of two Lolium varieties, respectively. Therefore, Lolium perenne is more insensitive to the high concentrations of O₃ than Lolium multiflorum, because the stomatal regulation and antioxidant capacity of Lolium perenne are stronger. This study provides a scientific basis and reference for screening ozone resistant grasses under global climate change.