土壤水分对湿地松幼苗光合特征的影响

通过设置常规供水(CK)、轻度干旱(T1)、水饱和(T2)、水淹(T3)4个处理组,研究湿地松当年实生幼苗在不同土壤水分条件下的光合生理响应及叶绿素荧光特性。结果表明:不同水分处理对湿地松幼苗的叶片气体交换参数、水分利用效率(WUE)、光合色素、叶绿素荧光参数等指标有不同的影响;其中,T3的光合色素含量最低;T2、T3组的湿地松幼苗表现出较低的净光合速率(Pn)、电子传递速率(ETR)和PSⅡ光化学的量子效应(ΦPSⅡ),但与其他耐水淹植物相比,T3条件下的湿地松幼苗仍具有较高的Pn,说明湿地松幼苗具有较强的耐水淹能力;在T1条件下,湿地松幼苗具有较高的WUE和较低的蒸腾速率(Tr)、气孔导度(Gs)以对抗干旱的逆境,其Pn、PSⅡ最大光化学效率(Fv/Fm)、ETR和ΦPSII均有所下降,但仍能维持在相对正常的水平。研究证明,湿地松幼苗具有一定的耐淹耐旱特性,可运用于三峡库区消落带的植被重建。

Effects of soil water regime on leaf photosynthetic characteristics of slash pine(Pinus elliottii Engelm)

Four treatments(normal soil water condition,CK;light drought condition,T1;water saturation condition,T2;and submersion condition,T3) were installed to study the responses in leaf photosynthesis and chlorophyll fluorescence parameters of slash pine(Pinus elliottii Engelm.) seedlings to different soil water regimes.Differences were observed in the responses of the leaf gas exchange parameters,water use efficiency(WUE),photosynthetic pigment contents,and chlorophyll fluorescence parameters to the soil water regimes.The photosynthetic pigment contents were the lowest in treatment T3,and the net photosynthetic rate(Pn),electron transport rate(ETR),and quantum yield of PSII photochemistry(ΦPSII) were lower in treatments T2 and T3,as compared with CK.The slash pine seedlings in treatment T3 still had a higher Pn than the other plant species that have high tolerance to inundation,indicating that the slash pine seedlings had high tolerance to inundation.In treatment T1,the seedlings kept high WUE,low stomatal conductance(Gs),and low transpiration rate(Tr) against the drought stresses,while decreased Pn,potential efficiency of primary conversion energy of PSII(Fv/Fm),ETR,and ΦPSII,though these parameters were still maintained at relatively normal level.The above results suggested that slash pine seedlings could not only tolerate water-logging,but also endure a certain degree of drought,and that slash pine could be a candidate species in re-vegetation of the Three Gorges Reservoir region.