温度胁迫对三七光合特性及生理指标的影响

[目的]研究三七对温度胁迫的生理响应,揭示三七的耐寒和耐热机制,为三七抗逆品种的选育、区域化种植和栽培管理提供理论依据.[方法]以盆栽生长第2年的三七植株为试验材料,利用人工气候培养箱进行5、10、25(对照)和35℃温度处理,持续处理48 h后测定三七叶片的光合特性及叶绿素含量、保护酶活性等生理指标,并分析其变化规律.[结果]在5~25℃的温度条件下,三七叶片的叶绿素a(Chla)、叶绿素b(Chlb)和总叶绿素[Chl(a+b)]含量呈先升后降的变化趋势,与25 ℃处理相比,5 ℃处理分别降低21.91%、23.30%和22.78%,10 ℃处理分别提高51.69%、52.43%和51.96%,差异均达显著水平(P<0.05,下同);与25℃处理相比,35℃高温条件下,Chla、Chlb和Chl(a+b)含量及Chl(a/b)分别降低14.61%、6.80%、11.74%和8.10%,差异均达显著水平.低温胁迫下,三七叶片的最大净光合速率(Pmax)、表观量子效率(a)、光饱和点(LSP)、净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著下降,胞间二氧化碳浓度(Ci)显著升高,光补偿点(LCP)呈先升后降的变化趋势;高温胁迫下,三七叶片的Pmax、LSP、Pn、Gs和Tr均显著下降,Ci、a和LCP则呈上升趋势.在低、高温胁迫条件下,三七叶片的过氧化氢酶(CAT)活性显著降低,过氧化物酶(POD)和超氧化物歧化酶(SOD)活性总体上显著升高;丙二醛(MDA)含量变化不明显.低温胁迫下三七叶片的可溶性蛋白含量显著升高.[结论]低、高温胁迫均显著抑制三七的光合能力.低温胁迫下,三七主要通过提高POD和SOD活性,增加可溶性蛋白和叶绿素含量来增强其抗冷性;高温胁迫下,三七主要通过提高POD和SOD活性来增强其抗热性.

Effects of temperature stress on photosynthetic characteristics and physiological indexes of Panax notoginseng(Burk.)F.H.Chen

[Objective]Physical response of Panax notoginseng(Burk.)F.H.Chen to low temperature stress and high temperature stress were studied,and its cold and heat resistance mechanism were revealed to provide theory basis for breeding of resistant varieties regionalized cultivation,cultivation and management of P. notoginseng.[Method]Potted second-year P.notoginseng seedlings were used as tested materials,and treated by 5,10,25(control)and 35℃in artificial climate box.After 48 h of continuous treatment,physiological indexes including photosynthetic characteristics,chloro-phyll contents,protective enzyme activities were studied and the changing rules were analyzed.[Result]Under the tem-perature from 5 to 25℃,the variation of chlorophyll a(Chla)content,chlorophyll b(Chlb)content and total chlorophyll (a+b)content rose at beginning then declined.Compared with 25℃treatment,the contents of chla,chlb,chl(a+b)re-spectively decreased 21.91%,23.30% and 22.78% in 5℃treatment,but compared with 10℃treatment,the contents of chla,chlb and Chl(a+b)respectively increased 51.69%,52.43% and 51.96% with the differences at significant level(P<0.05,the same below).Under 35℃treatment,the contents of chla,chlb and chl(a+b),and chl(a/b)decreased 14.61%, 6.80%,11.74% and 8.10% respectively comparing with 25℃treatment and the difference reached significant level.Under low temperature stress,maximum net photosynthetic rate(Pmax),apparent quantum efficiency(a),light saturation point (LSP),net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)decreased significantly,CO2 concentration(Ci)increased significantly and the change trend of the light compensation point(LCP)rose at beginning then declined.Under high temperature stress,Pmax,LSP,Pn,Gsand Trdecreased significantly,and Ci,a and LCP presented an increasing tendency. Under low and high temperature stress conditions,the activity of catalase(CAT)in P.notoginseng significantly reduced,and the activities of peroxidase(POD)and superoxide dismutase(SOD)generally increased signifi-cantly. Malonaldehyde(MDA)changed slightly. Under low temperature stress,soluble protein content significantly in-creased.[Conclusion]The photosynthetic capacity of P.notoginseng is significantly inhibited by low and high temperature stresses.Under low temperature stress,P.notoginseng enhances the cold tolerance mainly by improving the activities of POD and SOD,and increasing the contents of chlorophyll and soluble protein.Under high temperature,P.notoginseng en-hances the heat tolerance mainly by improving the activities of POD and SOD.