多效唑对大丽花叶片光合特性和超微结构的影响

Effects of paclobutrazol on the photosynthetic characteristics and ultrastructure of Dahlia pinnata leaves

以高生型大丽花品种‘陇上雄鹰’为试材,用不同浓度多效唑进行根灌处理,以清水为对照,研究多效唑对其生长发育、光合特性及超微结构的影响。结果表明,不同浓度多效唑处理均能使大丽花植株矮化,节间缩短,花径增大,观赏价值提高;随着处理天数的增加,大丽花叶片叶绿素含量和净光合速率均呈先升高后降低的变化趋势,在24d左右出现峰值;蒸腾速率、气孔导度和细胞间CO2浓度随天数的增加变化趋势不同;叶片光合能力的降低是气孔和非气孔因素共同作用的结果;75mg/L及以下浓度处理条件下,叶绿体、线粒体结构完整,基粒和基粒片层排列整齐,数目多于对照,光合能力强;100和125mg/L处理条件下,叶绿体、线粒体结构破坏,发生质壁分离现象,基粒和基粒片层发育不完整,严重影响光合作用。75mg/L浓度多效唑处理的效果最佳,花径最大,叶绿素含量最高,光合能力最强,观赏价值高。

To study the effects of paclobutrazol on growth,development,photosynthetic characteristics and chloroplast ultrastructure in Dahlia pinnata,the cultivar‘Longshangxiongying＇was treated with different concentrations of paclobutrazol and water was used as the control.Plant height was dwarfed,internodes were shortened,flower diameter increased and ornamental values enhanced under different paclobutrazol treatments.Chlorophyll contents and net photosynthetic rate initially increased but then decreased and were highest at the24 th day.Variation trends of transpiration rate,stomatal conductance and intercellular CO2 concentration differed with increasing treatment time.The photosynthetic capacity reduction was due to both stomatal factors and non-stomatal factors.At concentrations of 75mg/L and less,the chloroplast and mitochondrion structure were completed,the grana and grana lamella arranged appropriately,and the numbers of grana and grana lamella were higher than in the control,while the photosynthetic capacities were stronger.In the 100 and 125mg/L treatments,chloroplast and mitochondrial structures were damaged and plasmolysis occurred.The growth of grana and grana lamella was incomplete.These factors seriously influenced photosynthesis.The effect of 75mg/L paclobutrazol treatment was the best.In this treatment,chlorophyll contents of D.pinnata leaves were the highest,photosynthesis capacity was the strongest and the ornamental value of the D.pinnata were the highest.