缺钼对旺长期烤烟光合色素和荧光日变化及亚显微结构的影响

以模式作物烟草(Nicotiana tabacum)为试材,采用水培试验,以营养液含钼0.20mg·kg-1作为对照(CK),0mg·kg-1为缺钼处理(T),研究缺钼对旺长期烟草光合色素、叶绿素荧光日变化和叶片细胞亚显微结构的影响,以揭示钼对旺长期烟草光合作用影响及其作用机理。结果显示:(1)缺钼处理烟叶的叶绿素和类胡萝卜素含量显著低于施钼烟叶。(2)缺钼烟叶的日净光合速率(Pn)下降早于对照,而且回升较慢;施钼烟叶的Pn呈典型双峰日变化。(3)施钼烟叶的最大光化学效率(Fv/Fm)比较稳定;光合电子传递速率(ETR)和光合有效量子产量(Y)在14:00较低,16:00略有回升;初始荧光(F0)和非光化学猝灭系数(NPQ)在12:00~14:00略微增加,18:00恢复到8:00的水平。缺钼烟叶Fv/Fm在12:00明显降低,16:00后开始有所回升;10:00后,其ETR和Y开始下降,F0和NPQ急剧增加,16:00后开始有所降低,18:00未恢复到8:00的水平。(4)缺钼烟叶细胞亚显微结构的基粒片层和基质片层膨胀变形、松散,淀粉粒少而且发育差;施钼烟叶片层结构排列整齐,淀粉粒发育好。研究表明,旺长期缺钼烟叶的光合色素含量降低,细胞结构发育不良,叶绿素荧光受强光和高温反应敏感,净光合速率降低,光合碳同化产物减少。

Effect of Photosynthetic Pigments,Diurnal Changes of Fluorescence and Ultrastructure in Fast Growing Period of Flue-cured Tobacco to Molybdenum Deficiency

The effects on the photosynthetic pigments,the diurnal changes of chlorophyll fluorescence parameters and ultrastructure used by 0.20 mg·kg^-1 as CK and 0 mg·kg^-1 as molybdenum deficiency treatment were studied on flue-cured tobacco of fast growing period,which is one of the model crop materials.The results showed that:(1)The contents of chlorophyll and carotenoid in tobacco leaves under molybdenum deficiency were significantly lower than those under Mo-fertilized treatment.(2)The net photosynthetic rate(P_n) declined under molybdenum deficiency earlier than that under Mo-fertilized treatment in a day,and the P_n of tobacco in Mo-fertilized treatment was a typical bimodal daily variation.(3)Under molybdenum deficiency,the maximal photochemical efficiency(F_v/F_m)decreased significantly at 12:00 and increased slightly at 16:00.At 10:00,the electron transport rate(ETR) and the quantum yield(Y) began to decrease,but the initial fluorescence(F₀)and the non-photochemical quenching efficiency(NPQ) increased sharply,then they did not recover to the level at 8:00.In contrast,under Mo-fertilized treatment,the F_v/F_m was stable,ETR and Y reached the lowest point at 14:00 and then increase slightly at 16:00.F₀ and NPQ increased slower during 12:00-14:00,and recovered to the level at 8:00.(4)The grana layer of the ultrastructure of tobacco leaves under molybdenum deficiency expanded to deformation and loose.The amyloid number was less and grew worse.While the grana layer of the tobacco in Mo-fertilized treatment were arranged neatly,and the amyloid grew well.In summary,under molybdenum deficiency,the contents of the photosynthetic pigments of fast growing period tobacco decrease,ultrastructure grows worse,and the chlorophyll fluorescence parameters are sensitive to the bright-light and high-temperature,photosynthetic primary action is inhibited,so the P_n and photosynthetic carbon assimilation product decreased.