干旱胁迫下黄条金刚竹的光合和叶绿素荧光特性

Photosynthetic parameters and chlorophyll fluorescence characteristics of Pleioblastus kongosanensis f. aureostriaus under drought stress

通过盆栽试验,研究了自然干旱胁迫处理下,黄条金刚竹植株形态、土壤含水量（SWC）、叶片含水量（LWC）、叶片水势（LWP）、光合作用参数和叶绿素荧光参数的变化,及与环境因素的关系.结果表明：自然干旱胁迫后第17天,黄条金刚竹出现干旱伤害症状,叶片失水下垂、内卷,第43天地上部分失水死亡;复水后10 d,叶片叶绿素荧光参数与第43天无显著差异.在干旱胁迫0~21 d,SWC显著下降,而在17 d以后,LWP急剧下降,29 d以后LWC显著降低.随着干旱胁迫程度的加剧,叶片蒸腾速率（Tr）、气孔导度（gs）持续下降,而光合速率（Pn）波动较大,瞬时水分利用效率（PWUE）则先升高后降低;17 d后,Pn由气孔限制为主转为非气孔限制为主,实际光合效率（ΦPSⅡ）开始下降;25 d后,黄条金刚竹的光合机构被破坏,最大光化学效率（Fv/Fm）和PSⅡ潜在热耗散能力（qN）分别由0.64、0.79下降到-0.11、0.33.Tr、gs、PWUE与LWP密切相关,大气湿度对Pn、Tr、gs的影响显著,气孔是光合参数变化的主导因素.本试验条件下,黄条金刚竹适宜在土壤相对含水率≥12%的土壤中生长,且干旱胁迫持续时间不超过25 d.

A pot experiment was conducted to study the variations of Pleioblastus kongosanensis f.aureostriaus plant morphology,leaf water content（LWC）,leaf water potential（LWP）,photosynthetic parameters,chlorophyll fluorescence parameters,and soil water content（SWC） under natural drought stress,as well as the relationships between these variations and environmental factors.On the 17th day under the stress,the P.kongosanensis presented damaged symptom.Its leaves dehydrated,drooped,and wrap-formed.On the 43rd day,the aboveground part of the plant died from dehydration.When the plant was re-watered for 10 days,the chlorophyll fluorescence parameters had no significant differences with those on the 43rd day under the stress.The SWC decreased significantly in 0-21 d of the stress,and the LWP and LWC dropped rapidly and significantly after 17 d and 29 d,respectively.With the increase of drought stress,the leaf transpiration rate（Tr） and stomatal conductance（gs） had a persistent decline,photosynthetic rate（Pn） had a greater fluctuation,and instantaneous water use efficiency（PWUE） decreased after an initial increase.After 17 d drought stress,the limiting factor of Pn was from stomatal to non-stomatal,and the actual photosynthetic efficiency（ΦPSⅡ） declined significantly;after 25 d,the photosynthetic organ was damaged,and the maximum photochemical efficiency of PSⅡ（Fv/Fm） and non-photochemical quenching（qN） changed significantly from 0.64 to-0.11 and from 0.79 to 0.33,respectively.The Tr,gs,and PWUE had close correlations with LWP;the Pn,Tr,and gs were sensitive to air relative humidity（RH）;and the gs was the main factor causing the diurnal variations of photosynthetic parameters.It was suggested that P.kongosanensis could grow well on the soil with relative moisture content ≥12% and drought duration less than 25 d.