干旱胁迫对冬小麦幼苗叶片光合生理特性的影响

Effects of Drought Stress on Photosynthetic Physiology Characteristics in Winter Wheat Seedling Leaves

为了解冬小麦幼苗叶片光合生理指标对干旱胁迫的响应,以周麦22为材料,研究了20%PEG-6000持续胁迫以及复水对小麦幼苗叶片的光合作用、光合关键酶和抗氧化酶活性的影响。结果表明,随着干旱的持续,与对照组相比,干旱组小麦幼苗叶片的叶绿素(a+b),叶绿素a/叶绿素b,Rubisco活性及生物量均下降,根冠比增加;净光合速率及PEPC,PPDK,NADP-ME,SOD,CAT,APX,POD活性均呈先升后降趋势,最大增幅分别为18.4%(处理1 d),77.6%(处理1 d),79.2%(处理3 d),69.2%(处理1 d),155.6%(处理3 d),71.6%(处理3 d),129.4%(处理3 d),143.5%(处理1 d),复水3 d各参数均有所恢复。说明短期干旱胁迫诱导冬小麦幼苗叶片的C4途径光合酶活性的高表达,部分补偿了Rubisco活性下降对光合固碳造成的不利影响;诱导抗氧化酶活性的增加,有效增强了活性氧清除能力,减轻了氧化带来的伤害;C4途径光合酶可能在冬小麦耐旱生理机制中起着重要作用。

To understand the effects of drought stress on photosynthetic physiology parameters of winter wheat seedling leaves, this paper took Zhoumai 22 as material, and analyzed the effect of 20% PEG-6000 last for 7 days and re-water to the photosynthesis, the key photosynthetic enzymes and antioxidase activities of winter wheat seedling leaves. The result showed that as drought stress continuing,compared with the control, the Chl（a＋b）, Chla/Chlb, Rubisco activity and biomass all declined of wheat seedling leaves in the drought group, while the radio of root to shoot dry weight increased. Net photosynthetic rate and the enzymes activities in the leaves all showed a rise first followed by a decline. The maximum increase of net photosynthetic rate was 18.4% in one day after drought treatment, the activities of PEPC, PPDK, NADP-ME, SOD, CAT, APX and POD was 77.6%（1 d）,79.2%（3 d）,69.2%（1 d）,155.6%（3 d）,71.6%（3 d）,129.4%（3 d）,143.5%（1 d）, respectively. All of the parameters were restored in 3 days after re-water. These results indicated that short-term drought stress could enhance the activity of C4 pathway photosynthetic enzymes and it could partial offset the negative influence to photosynthetic carbon fixation with the decreasing of the Rubisco activity. It could increase the activity of antioxidases. The ability in clearing up active oxygen were effectively enhanced and could use it to reduce the harm of oxidation. C4 pathway enzymes might play an important role in physiological mechanism of drought-resistant of winter wheat seedlings.