水稻拔节期根系呼吸对臭氧污染和厌氧—有氧环境变化的响应

依托O3FACE(Free-Air O3 Enrichment)研究平台,研究了大气臭氧(O3)浓度增加对拔节期水稻根系呼吸和生物量积累分配的影响,利用特制集气装置分析了厌氧—有氧条件对根系呼吸的影响。结果表明,O3浓度升高水稻冠层和总生物量略有降低,而根干物重和根/冠比分别显著降低14.7%和10.4%。9∶1和9.5∶0.5的纯N2∶O2配比利于根系呼吸,纯N2或空气、CO2饱和蒸馏水条件不同程度降低了根系呼吸速率;高臭氧处理、对照处理的水稻根系呼吸速率分别在CO2饱和蒸馏水、纯N2条件下最小,表明尽管不同根系测定条件影响根系呼吸速率,但影响程度也受植物生长的大气环境制约。臭氧污染处理水稻根系的呼吸速率在气态测定条件下显著高于正常大气处理23.6%～52.7%,在CO2饱和蒸馏水测定条件下未达到显著水平,臭氧污染效应明显降低。两个环境生长的水稻根系呼吸均随测定根系气态环境供氧量的增加呈凸二次函数变化,5%～10%比例的氧气供应促进了根系呼吸,较强的厌氧环境(纯N2)和有氧环境(Air)均不利于水稻根系呼吸。

Response of rice root in respiration at jointing stage to ozone pollution and alternation of anaerobic and aerobic conditions

Effects of elevated atmospheric ozone (pO3) (50% higher than the ambient pO3 in concentration) on root respiration and biomass accumulation and distribution of rice (Oryza sativa L. cv. Xiandao 63) at the jointing stage were investigated in fully open-air field conditions, and effect of alternation of anaerobic and aerobic conditions on root respiration was analyzed using special gas-collecting installations. Results show that under elevated pO3 canopy and total biomass of the crop decreased slightly, while its root dry matter weight and ratio of root/canopy dropped significantly by 14.7% and 10.4%, respectively. The mixture of N2 and O2 at a ratio of 9:1 or 9.5:0.5 was the most propitious for root respiration, whereas in pure N2, natural air and CO2-saturated distilled water root respiration rate was lowered to a varying degree. The treatment of elevated pO3 coupled with measurement inn CO2-saturated distilled water and the treatment of ambient air coupled with measurement in pure N2 was the least in root respiration rate, indicating that although the condition in which root respiration was measured affected root respiration rate, the impact was restricted in degree by the atmospheric environment in which the plant grew. The root respiration rate of rice growing under elevated ozone was 23.6%~52.7% higher than that under natural atmosphere when measured in pure gas condition, and the difference between the two was insignificant when the measurement was done in CO2-saturated distilled water, showing that the influence of ozone pollution on root respiration obviously decreased. Under elevated and ambient pO3 environments, root respiration of the rice displayed a curve of convex quadratic function with increasing oxygen supply in the gaseous environment for measurement. The oxygen concentration of 5%~10% in the environment promoted rice root respiration, while stronge anaerobic condition (i.e., pure N2) and aerobic conditions (i.e., air) both affected root respiration of rice reversely.