干旱和盐胁迫对鸭茅叶绿素荧光动力学参数的影响

Responses of the chlorophyll fluorescence parameters of cocksfoot(Dactylis glomerata)to water and salt stress

为了研究鸭茅对干旱、盐胁迫的回馈,采用随机区组盆栽试验。试验包括4种相对含水量处理,相对含水量为75%(CK)、55%、35%、20%和3种盐浓度(100,70和35 mmol/L),以相对含水量75%作为对照,研究干旱胁迫和盐胁迫对叶绿素荧光参数的影响。结果表明:随着相对含水量的减少,鸭茅的非光化学荧光淬灭(NPQ)幅度逐渐降低,光化学淬灭系数(qP)逐渐增加;最大光化学效率(Fv/Fm)、潜在活性(Fv/F0)逐渐减少;电子传递速度(ETR)逐渐降低;实际原初光能的捕获效率Y(Ⅱ)降低。但在极度干旱胁迫时,热耗散能力降低,光合作用上升,潜在最大光合效率和潜在光合效率增加,实际原初光能的捕获效率增加;表明在极度干旱的条件下,鸭茅的内部机制会做出相应的反应,来避免恶劣的环境。盐胁迫时,低浓度促进热耗散幅度抑制光合作用,相反高浓度抑制剩余光能的转化和促进光合效率;鸭茅的Fv/Fm先上升后下降,Fv/F0与Fv/Fm有相同的趋势;ETR先上升后减少,原初光能的捕获效率先增加后降低。综合评定,鸭茅受盐胁迫影响大于干旱胁迫。

In order to understand the response of cocksfoot（Dactylis glomerata）to drought and salt stresses,apot experiment was conducted in a randomized completely block design.There were 7treatments including4 water stress treatments（75%,55%,35% and 20% of gravimetric water content）and 3salinity stress treatments（35mmol/L NaCl,70mmol/L NaCl and 100mmol/L NaCl）.The water content of 75% was used as control.After 20 days of the drought and salt stress treatment,the chlorophyll fluorescence parameters were measured using the chlorophyll fluometer.The results showed that Fv/Fm,Fv/F0,ETR,Y（Ⅱ）and NPQ gradually decreased,and qP increased with water content decreasing.However,under extreme water stress,heat dissipation was decreased,and photosynthesis and its efficacy were increased in cocksfoot,indicating that cocksfoot responded to water stress to avoid potential damage to the plants.With the increasing of salt stress level,Fv/Fmof cocksfoot initially increased and then declined.ETR,Fv/F0 and Y（Ⅱ）showed a similar trend as Fv/Fm.The heat dissipation increased at lower salinity levels but decreased at higher salinity levels.The photosynthesis responded in an opposite way to heat dissipation.The tolerance of cocksfoot to water stress was better than salt stress under the experimental conditions.