干旱和盐胁迫对鸭茅叶绿素荧光动力学参数的影响

摘要

In order to understand the response of cocksfoot (Dactylis glomerata )to drought and salt stres-ses,a pot experiment was conducted in a randomized completely block design.There were 7 treatments including 4 water stress treatments (75%,55%,35% and 20% of gravimetric water content)and 3 salinity stress treat-ments (35 mmol/L NaCl,70 mmol/L NaCl and 100 mmol/L NaCl).The water content of 75% was used as con-trol.After 20 days of the drought and salt stress treatment,the chlorophyll fluorescence parameters were meas-ured using the chlorophyll fluometer.The results showed that F v/F m ,F v/F 0 ,ETR,Y(Ⅱ)and NPQ gradually decreased,and qP increased with water content decreasing.However,under extreme water stress,heat dissipa-tion was decreased,and photosynthesis and its efficacy were increased in cocksfoot,indicating that cocksfoot re-sponded to water stress to avoid potential damage to the plants.With the increasing of salt stress level,F v/F m of cocksfoot initially increased and then declined.ETR,F v/F 0 and Y(Ⅱ)showed a similar trend as F v/F m .The heat dissipation increased at lower salinity levels but decreased at higher salinity levels.The photosynthesis re-sponded in an opposite way to heat dissipation.The tolerance of cocksfoot to water stress was better than salt stress under the experimental conditions.%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(N PQ)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 F v/F m 先上升后下降,F v/F 0与 F v/F m 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。