铁对缺磷和铝毒耦合胁迫下杉木耐铝性的影响

Effects of Iron on Aluminum Tolerance of Cunninghamia lanceolata under Combined Phosphorus Deficiency and Aluminum Toxicity Stress

为探究酸性土壤中铁与缺磷和铝毒耦合胁迫的互作关系及其对杉木耐铝性的影响,以杉木优良基因型YX11实生苗为材料,采用控制条件下沙培试验方法,设置对照(CK)、铝胁迫(Al)、缺磷和铝毒耦合胁迫(-P+Al)、缺磷和铝毒耦合胁迫下缺铁处理(-P+Al-Fe),研究缺磷和铝毒耦合胁迫下,外源供铁对杉木幼苗生长、光合生理、植株铝和铁含量、叶片抗性生理的影响。结果表明:(1)Al胁迫处理能显著抑制杉木幼苗生长,-P+Al处理进一步加剧Al诱导的生长受抑,而-P+Al-Fe处理则能显著缓解-P+Al处理引起的生长受抑程度。(2)杉木叶片光合色素含量,叶绿素荧光参数最大荧光(F_(m))、可变荧光(F_(v))、PSⅡ潜在光化学活性(F_(v)/F_(o))、PSⅡ最大光化学效率(F_(v)/F_(m))、光化学淬灭系数(qP)和实际最大量子产额(QY)以及叶片净光合速率在不同胁迫处理下均较CK出现不同程度下降,但-P+Al处理的降幅显著大于-P+Al-Fe处理。(3)杉木叶片SOD、POD、CAT和APX等抗氧化酶活性在不同胁迫处理下均比CK显著增加,但-P+Al处理各抗氧化酶活性增幅显著低于-P+Al-Fe处理,从而导致-P+Al处理叶片形成更多过氧化氢,积累大量丙二醛。(4)杉木根和叶片铝含量在不同胁迫处理下均比CK显著增加,但根和叶片中铝含量在-P+Al-Fe和-P+Al处理间无显著差异,而-P+Al处理根和叶片中铁含量显著高于-P+Al-Fe处理。研究发现,在缺磷和铝毒耦合胁迫下,与缺铁相比,正常供铁能显著促进铁在杉木植株体内的积累,抑制其抗氧化酶活性的增强,促进过氧化氢大量积累,造成光合色素降解,同时对质膜和光合反应中心造成不可逆损伤,显著降低光合效率,加剧铝毒诱导的杉木生长受抑程度。

To explore the interaction of iron(Fe)with phosphorus(P)deficiency and aluminum(Al)toxicity coupling stress in acidic soil and its effects on Al tolerance of Cunninghamia lanceolata,we conducted sand culture method with four treatments:Control(CK),Al stress(Al),P deficiency and Al toxicity coupling stress(-P+Al)and P deficiency and Al toxicity coupling stress without Fe(-P+Al-Fe)under controlled conditions in this study to investigate the effects of exogenous application of Fe on the growth,photosynthetic physiology,Al and Fe contents and resistance physiology in leaves of C.lanceolata seedlings under P deficiency and Al toxicity coupling stress by using superior genotype seedlings of C.lanceolata YX11.The results showed that:(1)Al stress could significantly inhibit the growth of Chinese fir seedlings,and the growth inhibition induced by Al was further aggravated by normal iron supply under the coupling stress of phosphorus deficiency and aluminum toxicity(-P+Al),-P+Al-Fe significantly alleviated the growth inhibition induced by-P+Al treatment.(2)Compared with CK,the photosynthetic pigment content,chlorophyll fluorescence parameters including maximal fluorescence(F_(m)),variable fluorescence(F_(v)),PSⅡpotential photochemical activity(F_(v)/F_(o)),PSⅡmaximal photochemical efficiency(F_(v)/F_(m)),photochemical quenching coefficient(qP),actual maximum quantum yield(QY)and net photosynthetic rate of Chinese fir leaves all decreased in different degrees under various stress treatments.However,a more significantly decreasing amplitude of above indexes was observed in-P+Al treatment as compared with-P+Al-Fe treatment.(3)The activities of SOD,POD,CAT and APX in leaves of C.lanceolata were significantly increased under different stress condition when compared with CK,and the increasing amplitude of these enzyme activities in-P+Al treatment was significantly lower than that in-P+Al-Fe treatment,which in turn leads to higher accumulation of malondialdehyde in-P+Al treatment as resulted by the formation of hydrogen peroxide.(4)Different stress treatments all resulted in a significantly higher accumulation of Al content in both roots and leaves of C.lanceolata seedlings as compared with CK,while no significant difference of Al content was noted between-P+Al-Fe and-P+Al treatments.Moreover,a significantly higher of Fe content in both roots and leaves of C.lanceolata seedlings was found in-P+Al treatment as compared with-P+Al-Fe treatment.The above results demonstrated that under phosphorus deficiency and aluminum toxicity coupling stress,compared with Fe deficiency,normal Fe supply could significantly promote the accumulation of Fe in plants,thus the increase of antioxidant enzyme activity was inhibited,and increased the accumulation of hydrogen peroxide,which in turn caused degradation of photosynthetic pigments and irreversible damage to the plasma membrane and photosynthetic reaction center,resulted in significant decrease of photosynthetic efficiency and ultimately the growth inhibition induced by Al was aggravated.