外源硅对盐胁迫下棉花幼苗光合、荧光及抗氧化酶活性的影响

Effects of Exogenous Silicon on Photosynthetic, Chlorophyll Fluorescence and Antioxidant Enzymes Parameters of Cotton Seedlings under Salt Stress

【目的】研究外源硅提高棉花幼苗抗盐性的效应。【方法】以棉花品种新陆早45号为试验材料,采用营养液培养法,研究外源硅对不同程度盐胁迫下棉花幼苗光合色素含量、光合气体交换参数、叶绿素荧光参数及抗氧化酶活性的影响。【结果】盐胁迫下棉花幼苗叶绿素a(Chla)、叶绿素b(Chlb)、叶绿素总量(Chla+b)和类胡萝卜素含量均随着盐浓度的升高而降低,而施用外源硅后均呈上升趋势。棉花幼苗净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)均随盐浓度升高而逐渐下降,施用外源硅后可缓解光合参数下降趋势。盐胁迫下棉花幼苗光化学猝灭系数(qP)、非光化学猝灭系数(qN)、PSⅡ调节性能量耗散的量子产额[Y(NPQ)]和PSⅡ非调节性能量耗散的量子产额[Y(NO)]逐渐减小,施用外源硅后可使qP等荧光参数值上升,但各处理间差异并不显著。外源硅改善了盐胁迫对棉花幼苗光合色素生物合成和光合气体交换能力的抑制效应,提高了抗盐性。盐分胁迫下,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等三种抗氧化酶的活性均随盐浓度升高降低,而施硅则提高了SOD、POD和CAT抗氧化酶的活性。【结论】外源硅能提高盐胁迫下棉花幼苗光合、叶绿素荧光及抗氧化酶活性,阻止盐胁迫下有害物质的积累,提高了棉花幼苗的抗盐能力。

【Objective】To investigate the effect of applying exogenous silicon to improve cotton seedlings salt resistance,【Method】Cotton Xinluzao 45 was used as the experimental material,and a nutrient solution hydroponic experiment was carried out to study the effects of exogenous silicon on photosynthetic pigment content,photosynthetic parameter and chlorophyll fluorescence parameters of cotton seedlings under different degrees of salt stress.【Result】Chla,Chlb,total chlorophyll and carotenoid of cotton seedling were decreased with increase of salt concentration under salt stress and these photosynthetic pigment contents showed a rising trend by exogenous silicon.The Pn,Tr,Gs and Ci of cotton seedlings were gradually decreased with increase of salt concentration under salt stress,and exogenous silicon alleviated the decline of photosynthetic parameters.The qP,qN,NPQ and Y(NO)of cotton seedlings were gradually decreased under salt stress and increased by exogenous silicon,however,there was no significant difference among the treatments.Exogenous silicon improved the inhibitory effect of salt stress on photosynthetic pigment biosynthesis and photosynthetic gas exchange ability of cotton seedling,improved salt resistance.Under salt stress,the enzyme activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)were decreased with the increase of salt concentration,while the activities of antioxidant enzymes such as SOD,POD and CAT were increased by applying silicon.【Conclusion】Exogenous silicon can increase photosynthetic,chlorophyll fluorescence and antioxidant enzyme activities of cotton seedlings under salt stress,prevent the accumulation of harmful substances under salt stress,and improve the salt tolerance ability of cotton seedlings.