地表臭氧胁迫对北方冬小麦光合及生理特征的影响

为进一步探明北方地区地表臭氧（O3）浓度增加对冬小麦光合日变化、光响应能力和气体交换的影响,通过开顶式气室（OTC）,利用LI-6400便携式光合仪,开展了4种O3熏气水平下光合作用的原位测定（碳滤空气,CF;自然空气,NF;100 nL.L-1,CF100;150 nL.L-1,CF150）。结果表明,在拔节初期,4个处理组间的净光合速率Pn、气孔限制值Ls及胞间CO2浓度Ci均无显著差异。在抽穗期,CF100、CF150处理的Pn较CF降低了37.0%~41.8%,气孔导度Cond下降了35.7%~38.9%,Ci上升了6.7%~10.5%。在灌浆期,CF100的最大光合速率Pm、半饱和光强Ik较CF降低了23.5%~46.7%,暗呼吸速率Rd增加了8.6%;CF150的Pm、表观量子产额AQY和Ik较CF下降了10.4%~26.1%,光补偿点LCP和Rd增加了51.2%~88.0%。随着O3浓度和熏蒸时间的增加,冬小麦叶片的叶绿素Chl和类胡萝卜素Car含量显著降低,而可溶性糖和丙二醛MDA含量明显增加,且均在灌浆期差异最显著。以上结果表明,O3对冬小麦光合作用的抑制作用具有明显的时间累积效应,且随熏气时间的延长,叶片光合作用的限制条件由气孔因素主导向非气孔因素主导转变;同时,O3胁迫使植株对强光的耐受性及对强、弱光的利用效率均下降。

Effects of Ozone Stress on Photosynthesis and Physiological Characteristics of Winter Wheat in Northern China

Experiments designed to investigate the effects of ozone（O3）stress on photosynthesis,gas exchange and physiological characteris-tics of winter whea（tTriticum aestivum L.Fengkang 13）were conducted in open-top chambers.The crops were exposed to charcoal-filtered ai（rCF）,non-filtered ai（rNF）and filtered air plus extra ozone（CF100 or CF150,100 or 150 nL.L-1 O3）,for 8 hours per day,totally 67 days in 2009.Results demonstrated that in jointing stage,the net photosynthetic rate（Pn）,stomatal limitation（L）sand intercellular CO2 concentra-tion（C）iof winter wheat leaves were not significant difference among the 4 treatments,but in heading stage,treatments with CF100 and CF150 caused 37.0%~41.8% reductions in Pn,35.7%~38.9% in stomatal conductance（Cond）,while 6.7%~10.5% increment for Ci,as compared to CF treatment.By filling stage,the maximum photosynthetic rate（Pm）and half-saturation light intensity（Ik）of CF100 reduced 23.5%~46.7% comparison with CF,while dark respiratory rate（Rd）increased 8.6%;When CF150 treatment was applied,the Pm,apparent quantum yield（AQY）and Ik decreased 10.4%~26.1%,light compensation poin（tLCP）and Rd increased 51.2%~88.0%.With increasing of concentration or time of O3 treatment,Chlorophyll and Carotenoids contents in winter wheat leaves were significantly decreased,while the soluble sugar and malondialdehyde（MDA）contents were obviously increased,which was mainly observed in filling stage and significant difference with CF treatment.We concluded that：the O3 stress had obvious impact on photosynthesis and physiological characteristics of winter wheat,and with the increase of time of O3 treatment,the time cumulative effect became stronger;at earlier growth stage,the photosynthesis capability was mainly restrained by stomatal factors,but at later growth stage,the non-stomatal limitation was more significant;the O3 stress also weak the endurance of plants to strong light,which result in declining of light used efficiency in leaves.