盐胁迫对朴树和速生白榆幼苗光合特性及叶绿素荧光参数的影响

Photosynthetic Characteristics and Chlorophyll Fluorescence Parameters of Celtissinensisand Ulmus pumila L. Seedling under Salt Stress

以1年生的朴树和速生白榆幼苗为试材,采用山东省林业科学研究院东营分院34.6‰的地下天然盐水配制所需盐水浓度,定期定量浇灌,使土壤分别达0(CK)、2‰、2.5‰、3.5‰和5‰的含盐量,各处理胁迫45d后测定其生长量(地径、苗高)、叶绿素含量、光合参数以及叶绿素荧光特性的变化,研究不同盐胁迫处理对朴树和速生白榆生长及光合作用的影响,探究其耐盐能力。结果显示:(1)整个盐胁迫过程中速生白榆的生长量较朴树高,但随着盐胁迫强度的增加朴树幼苗叶绿素含量呈先升高后降低的变化趋势,速生白榆幼苗则低于CK呈下降趋势。(2)朴树和速生白榆初始荧光(F_o)、最大荧光(F_m)和PSⅡ最大光能转化效率(F_v/F_m)均表现出下降趋势,与朴树相比速生白榆的F_o、F_m和F_v/F_m下降不明显,但在>2.5‰盐胁迫下速生白榆的非光化学猝灭系数(NPQ)较朴树增加更明显。研究表明,朴树叶绿素含量在每个盐胁迫浓度下均显著高于速生白榆,但在大于2.5‰浓度胁迫下速生白榆的荧光参数变化较朴树占优势;在非环境胁迫及较低盐胁迫条件下(≤2.5‰),朴树较速生白榆具有更好的光化学性能,但在较高盐胁迫条件下(>2.5‰),速生白榆光合参数及荧光参数较朴树变化稳定,能更好的适应盐胁迫环境。

The annual Celtis sinensis and Ulmus pumila L.seedlings as test material to measure the growth,chlorophyll content,photosynthetic characteristics and chlorophyll fluorescence parameters of C.sinensis and U.pumila The desired salt concentration is made up 34.6‰ of the underground natural saline water,the soil reached 2‰,2.5‰,3.5‰ and 5‰ salinity separately.The growth（height and ground diameter）,varieties of chlorophyll content,photosynthetic characteristics and chlorophyll fluorescence parameters of C.sinensis and U.pumila were measured after 45 days to study their salt tolerance.The results showed that：（1）the growth of U.pumila was always higher than that of C.sinensis in all saltstress test.The C.sinensis chlorophyll content increased first,and then decreased,but,chlorophyll content of U.pumilaless than control group and declined in every salt treatment.（2）Under different salt stress,initial fluorescence（F_o）,maximal fluorescence（F_m）and photo-chemical efficiency of PS Ⅱ（F_v/F_m）of C.sinensis and U.pumilaare dropped.Compare these two species,these fluorescence parameters（F_o,F_m,F_v/F_m）of U.pumilaslightly decrease,but,the non-photochemical quenching coefficient（NPQ）of U.pumilaincreased significantly than that of C.sinensis when soil salt content more than 2.5‰.The chlorophyll content of C.sinensisis always higher than that of U.pumilaunder every salt stress,but the chlorophyll fluorescence is lower under higher salt stress condition（〉2.5‰）;Under the condition of nonstress and lower salt stress,C.sinensis leaves possess better photochemical performance than that of U.pumilaleaves.In conclusion,when soil salt content was higher（〉2.5‰）.the changes of the photosynthetic and fluorescence parameters of U.pumila more stable than that of C.sinensis.Consequently,under salt stress environment,U.pumilacan better adapt to salt stress environment than C.sinensis.