大气O3浓度升高对玉米光合作用和籽粒品质的影响

Effects of Elevated Ozone Concentration on Maize Photosynthesis and Grain Quality

利用开顶式气室研究了大气O3浓度升高对玉米(Zea mays L.)叶片光合作用、籽粒品质以及产量的影响。结果表明,整个生长季内,与对照相比,在高浓度O3(80 nmol/mol)条件下,玉米叶片的净光合速率、气孔导度、蒸腾速率显著下降(p<0.05),而胞间CO2浓度先降低后升高并达到极显著水平(p<0.01),这说明使光合速率降低的主要因素由气孔限制逐渐转变为非气孔限制。与对照相比,高浓度O3处理植株叶绿素a、叶绿素b及叶绿素(a+b)含量降低,叶绿素a/b值则先降低后升高。但是随着熏蒸时间的延长,高浓度O3处理植株的叶绿素a、叶绿素(a+b)含量与叶绿素a/b值变化呈先升高后降低的趋势,与叶绿素b含量变化不同;O3浓度升高在一定程度上使玉米籽粒品质下降,其中蛋白质和淀粉含量降低,而粗脂肪和蛋脂总量略有升高;百粒重、穗粒数和穗粒重均显著低于对照(p<0.05),说明O3浓度升高降低了玉米的光合能力,籽粒品质受到影响,抑制了作物生长。

In recent years, the elevated ozone has some significant effects on plant photosynthesis, respiration, water availability and so on. Effects on maize photosynthesis, grain quality and yield were researched in open-top chambers under elevated ozone. The results showed that the photosynthesis rate, stomatal conductance and transpiration rate reduced significantly（p 〈 0.05 ） under elevated ozone （80 nmol/mol） in whole growing season, but intercellular CO2 concentration declined first and ascended following and attained highly significance level（p 〈 0.01 ）, which illuminated the decrease of the photosynthesis rate was mainly attributed to stomatal limitation,then turned to non-stomatal limitation, chlorophyll a, chlorophyll b and cblorophyll（a ＋ b）of the elevated ozone were lower obvious than that of control, but with the ratio of chlorophyll a to chlorophyll b declined first and ascended then. But with the lengthening of fumigation time, chlorophyll a, chlorophyll（a ＋ b）and the ratio of chlorophyll a to chlorophyll b of the elevated ozone ascended first and declined then, which was different from chlorophyll b. The elevated ozone decreased grain quality of maize to some extent. Protein and starch content decreased, but the coarse fat content and the gross of protein and fat increased. 100-grain weight, grain number per spike and weight per spike were lower than that of control （p 〈 0.05）, which revealed maize ability of photosynthesis decreased and unbeneficial to plant growth under elevated ozone concentration.