摘要:研究气孔对干旱胁迫的响应有助于了解气孔调节真实行为和提高水分利用效率。本研究以‘国欣9号’为供试棉花品种，在人工气候室利用营养液培养，设置加入PEG-6000浓度为0（对照）、1.5%、3.0%和4.5% 4个处理，处理后1~7 d每隔1 d连续测定其气孔形态、光合和叶绿素荧光指标。结果表明：加入PEG-6000 1 d后，随着处理进程的延长，棉花叶片水势、气孔长度、宽度和开度、净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、最大光化学效率（Fv/Fm）和实际光化学量子产量（Yield）均呈下降趋势，气孔密度和非光化学淬灭系数（NPQ）呈上升趋势；不同处理之间，随着干旱胁迫程度增加，也表现出相似趋势。处理后5 d和7 d，与正常处理相比，1.5%、3.0%和4.5%处理棉花气孔长度、宽度、水势、Pn、Gs、Tr和Ci均差异显著（P < 0.05），气孔长度降低幅度最小（1.17%~2.61%），Gs降低幅度最大（61.62%~69.09%），Tr降低幅度为37.62%~67.48%。相关分析表明，棉花气孔长度、宽度和开度之间极显著正相关（P < 0.01），气孔宽度和气孔密度不相关。气孔长度、宽度和开度与Pn和Yield极显著正相关（P < 0.01），与NPQ极显著负相关（P < 0.01），与Gs、Tr和Fv/Fm相关不显著。综上，棉花在PEG-6000诱发干旱后，通过降低气孔开度和增大气孔密度降低净光合速率和气孔导度，叶绿素荧光指标Yield和NPQ比Fv/Fm对干旱更敏感。
关键词:棉花/
气孔形态/
气孔密度/
光合特性/
干旱胁迫/
叶绿素荧光
Abstract:Studying the response of stomata to drought stress can help to understand the behavior of stomatal regulation and improve water utilization efficiency of crops. This study was conducted in an artificial climate chamber using the cotton cultivar 'Guoxin 9'. Four concentrations of PEG 6000[0 (control), 1.5%, 3%, and 4.5%] were added into the nutrient solution. Stomatal morphological parameters, gas exchange parameters, and chlorophyll fluorescence kinetic parameters were measured every two days from the first day to the seventh day of treatment. The results showed that with the elongation of treatment time, the values of leaf water potential, stomatal length, stomatal width, stomatal aperture, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular CO2 concentration (Ci), maximal photochemical efficiency (Fv/Fm), and actual photochemical production quantum (Yield) all decreased to some extent, whereas stomatal density and non-photochemical quenching coefficient (NPQ) increased. Similar trends were observed in different treatments with an increase in drought stress. After 5 d and 7 d of treatment, leaf water potential, stomatal length, stomatal width, Pn, Gs, Tr, and Ci with 1.5%, 3%, and 4.5% PEG 6000 were significantly different from those with the control (P < 0.05). The magnitudes of the declines in leaf stomatal length, Gs, and Tr were 1.17%-2.61%, 61.62%-69.09%, and 37.62%-67.48%, respectively. Correlation analysis revealed that significant positive correlations existed among leaf stomatal length, width, and aperture (P < 0.01). Stomatal width was not significantly correlated with stomatal density. Stomatal length, width, and aperture were positively correlated with Pn and Yield (P < 0.01), negatively correlated with NPQ (P < 0.01), and not significantly correlated with Gs, Tr, or Fv/Fm. These results suggested that the simulated drought induced by PEG 6000 may result in cotton stomatal closure and an increase in stomatal density, along with decreases in net photosynthetic rate and stomatal conductance. Compared with Yield and NPQ, Fv/Fm was less sensitive to drought stress in cotton.
Key words:Cotton/
Stomatal morphology/
Stomatal density/
Photosynthetic characteristics/
Drought stress/
Chlorophyll fluorescence
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