供铁水平对杉木幼苗叶片叶绿素荧光参数和抗氧化酶活性的影响

Effect of Fe Supply on Chlorophyll Fluorescence Parameters and Antioxidant Enzyme Activities in Leaves of Cunninghamia lanceolate Seedlings

【目的】铁元素在植物生长发育过程中需求量最大,在植物光合作用、叶绿素合成以及呼吸过程等生理活动中起着重要的作用。但当铁浓度超过植物所需的正常水平时,会对植物产生胁迫作用,不利于其生长发育。探究不同供铁水平对杉木幼苗内在生理机制的影响,为杉木人工林的科学经营提供理论依据。【方法】以1年生杉木幼苗为研究对象,通过室内砂培盆栽试验,在改良霍格兰完全营养液:铁浓度分别为20 mg/kg(T1)、30 mg/kg(T2)、40 mg/kg(T3)条件下,以常规霍格兰完全营养液为对照(CK),测定其15,30,45,60 d时杉木幼苗叶片叶绿素含量、荧光参数、丙二醛含量和抗氧化酶活性的变化。【结果】随处理浓度增加,叶绿素b和叶绿素a+b含量呈现先升高后降低的趋势,而叶绿素a/b含量表现出先降低后升高。在45 d、60 d时,T1、T2、T3叶绿素a含量均与CK处理间达显著性差异(P<0.05)。F_(0)含量随着铁浓度的升高也不断升高,而F_(m)、F_(v)/F_(m)、F_(v)/F_(0)和F_(m)/F_(0)则呈现不断下降的趋势,在处理30 d时,T3处理下的F_(m)、F_(v)/F_(0)、F_(m)/F_(0)相较于CK处理而言降低最明显,且CK处理下的F_(m)、F_(v)/F_(0)和F_(m)/F_(0)与T1、T2、T3处理达显著性差异(P<0.05),F_(0)和F_(v)/F_(m)含量未达显著差异(P>0.05)。不同铁浓度处理下的丙二醛含量均高于CK处理,随着铁浓度升高,其含量整体呈现降低后升高的趋势。而超氧化物酶、过氧化氢酶和多酚氧化酶活性均以CK处理最高,过氧化氢酶随着铁浓度升高,其活性呈现先降低后升高的趋势,且在15 d时,不同处理酶活性与CK处理间存在显著性差异(P<0.05),而超氧化物歧化酶活性随处理浓度的提升不断降低,但各处理间差异未达到显著水平(P>0.05);多酚氧化酶和过氧化物酶在各个培养时间上,随铁浓度的升高其酶活性未呈现出规律的变化,且在试验期间差异均未达到显著水平(P>0.05)。【结论】本研究中当年生叶为新叶,对铁的耐受性较低。营养液中铁处理浓度的增加使杉木幼苗叶片细胞膜系统受到损伤,叶绿素合成减缓,光合作用受阻。

[Objective]Iron element plays an important role in the growth and development of plants,namely,in their physiological activities.such as photosynthesis,chlorophyll synthesis,and respiratory processes.However,when the Fe2+concentration exceeds the normal level required by the plant,it will have a stress effect on it,which is not conducive to its growth and development.The aim of this study was to explore the influence of different iron supply levels on the internal physiological mechanism of Cunninghamia lanceolate seedlings,and provide a theoretical basis for the scientific management of Cunninghamia lanceolate seedlings.[Method]Through indoor sandbop potted test,with 1 year Cunninghamia lanceolate seedlings as the research object,in this study three Fe addition treatments with improved Hoagland complete nutrient solution were set up[the Fe concentrations were 20 mg/kg(T1),30 mg/kg(T2)and 40 mg/kg(T3)],respectively,and Hoagland complete nutrient solution as the control(CK),and chlorophyll content,fluorescence parameters,malondialdehyde content and antioxidant enzyme activity in leaves of Cunninghamia lanceolate seedlings were measured at 15 d,30 d,45 d and 60 d.[Result]With the increase of the treatment concentration,the contents of chlorophyll b and chlorophyll a+b showed a trend of first increasing and then decreasing,while the content of chlorophyll a/b showed a trend of decreasing first and then increasing.At 45d and 60d,the chlorophyll a contents of T1,T2 and T3 were significantly different from those of CK treatment(P<0.05).The content of F_(0) increased with the increase of iron concentration,while the contents of F_(m),F_(v)/F_(m),F_(v)/F_(0) and F_(m)/F_(0) showed a declining trend.After 30 days of treatment,the contents of F_(m),F_(v)/F_(0) and F_(v)/F_(0) in T3 treatment decreased the most significantly compared with CK treatment,and those of F_(m),F_(v)/F_(0) and F_(m)/F_(0) in CK treatment were significantly different from those in T1,T2 and T3 treatments(P<0.05),F_(0) and F_(v)/F_(m) contents did not show significant differences(P>0.05).The content of malondialdehyde in different iron concentration treatments was higher than that in CK treatment.As the iron concentration increased,its content showed an overall trend of decreasing and then increasing.However,the activities of superoxidase,catalase and polyphenol oxidase were the highest in CK treatment.With the increase of iron concentration,the activity of catalase showed a trend of first decreasing and then increasing,and at 15 days,diferent enzyme activities were significantly different from those in CK treatment(P<0.05),while the activity of superoxide dismutase continued to decrease with the increase of treatment concentration,the difference among the treatments did not show significant difference(P>0.05).The activity of polyphenol oxidation enzyme did not show a consistent law with the increase of concentration.The enzyme activities of PPD and POD didn’t change regularly wity the increase of iron concentration at each culture time,and the difference treatments didn’t reach significant correlated during the test period(P>0.05)[.Conclusion]In this study,the lobe was new leaf,and the tolerance to iron was low.The increase of Fe2+concentration in the nutrient solution damaged the cell membrane system,slowed down chlorophyll synthesis and blocked photosynthesis of seedling leaves of Cunninghamia lanceolate.