摘要
采用营养液水培法,研究了施用不同浓度外源硅(0、0.5、1.0 mmol/L)对干旱胁迫(10%PEG、20%PEG)下烟草幼苗生长、叶片光合特性和生理指标的影响。结果表明:干旱胁迫严重抑制了烟草幼苗生长和光合作用,膜质稳定性降低和引起氧化应激反应;施用不同浓度外源硅有效改善了干旱胁迫下烟草幼苗生长,均表现为株高、叶面积、根系体积、根系干重和地上部干重等生长指标增加,提高叶绿素a、叶绿素b、叶绿素a+b和类胡萝卜素含量,显著提高净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)并降低胞间CO2浓度(Ci),膜质过氧化产物MDA含量显著降低,提高叶片含水量、膜稳定性系数和渗透调节物质(脯氨酸、可溶性糖)含量,显著提高SOD、POD和CAT等抗氧化酶活性,而且1.0 mmol/L Si处理对干旱胁迫下烟草幼苗生长和生理特性的影响显著优于0.5 mmol/L Si处理。以上结果说明,施用外源硅能提高干旱胁迫下烟草幼苗光合作用、抗氧化和渗透调节能力,缓解干旱胁迫对烟草幼苗的伤害,促进其生长。
The effects of different concentrations of exogenous silicon(0,0.5,and 1.0 mmol/L)on the growth,Leaf photosyntheticcharacteristics and physiological indexes of tobacco seedlings under drought stress(10% PEG and 20% PEG)were studied using nutrientsolution culture method. The results showed that drought stress severely inhibited the growth and photosynthesis of tobacco seedlings,anddecreased membrane stability and induced oxidative stress response. Application of different concentrations of exogenous silicon effectivelyimproved the growth of tobacco seedlings under drought stress,showing that the growth indices such as plant height,leaf area,rootvolume,dry weight of root and shoot increased;the contents of chlorophyll a,chlorophyll b,chlorophyll a+b,and carotenoids increased;the net photosynthetic rate(Pn)and transpiration rate(Tr)and stomatal conductance(Gs)significantly increased,while intercellularCO2 concentration(Ci)decreased;MDA content of membrane peroxidation product significantly reduced;and water content of leaves,membrane stability coefficient,and osmotic adjustment substance(proline and soluble sugar)content significantly increased. The activities ofantioxidative enzymes such as SOD,POD and CAT increased. The 1.0 mmol/L Si treatment significantly affected the growth and physiologicalcharacteristics of tobacco seedlings under drought stress better than 0.5 mmol/L Si treatment. All above results revealed that the application ofexogenous silicon may improve the photosynthesis,antioxidation and osmotic adjustment ability of tobacco seedlings under drought stress,relieve drought damage on tobacco seedlings,and promote its growth.
引文
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