外施氯对油菜幼苗生长和光合特征影响的研究

采用盆栽砂培试验，研究了不同浓度氯离子（Cl-）处理对油菜（Brassica napus L.）幼苗干物质积累速率（DMAR）、根冠比（R/S）、叶绿素（Chl）含量、氯离子含量（Cl-）、净光合速率（Pn）、气孔导度（Gs）、细胞间CO2浓度（Ci）、蒸腾速率（Tr）、水分利用效率（WUE）、气孔限制值（Ls）等的影响。结果表明:25～100 mmol/L Cl- 处理9 d和18 d，油菜幼苗植株DMAR均上升，均在50 mmol/L Cl- 处理时达到最大值；不同浓度Cl- 处理9 d，Chl含量有先上升后下降的趋势，在100 mmol/L Cl- 处理时达到最大值，处理18 d，Chl含量依次下降。Cl- 处理能显著提高叶片中的Cl- 含量。除了在处理18 d后的Ci外，25～100 mmol/L Cl- 处理下，油菜叶片均能维持较高的Pn、Gs、Ci和Tr，200 mmol/L Cl- 处理9 d和18 d，油菜叶片Pn、Gs、Ci和Tr均显著下降。随着Cl- 浓度的增加，WUE呈现先降后升，在9 d处理后，随着Cl- 浓度的增加，油菜Ls也呈现先升后降，而在18 d处理后，随着Cl- 浓度的增加，Ls逐渐显著上升。上述结果表明，外施低量氯（Cl- 25~100 mmol/L）显著提高或者维持油菜幼苗的光合作用和蒸腾作用，促进油菜幼苗的生长；而高氯（200 mmol/L Cl-）条件下显著降低其光合作用和蒸腾作用，抑制其生长，且抑制油菜幼苗光合的主要是气孔因素。相关性分析还表明，植株DMAR、Pn、Ci、Tr、Gs之间均有显著的正相关性，而Pn与WUE之间存在极显著的负相关。

Effects of chloride on growth, photosynthetic traits of canola seedlings

Soil salinization not only is a serious environmental problem but also poses a severe threat to plant growth and agricultural production.The ions of Na+ and Cl-are mainly responsible for salinization.People generally pay close attention to study the Na+ effects on grow,productivity and quality of crop plant,however,relatively much less studies are on Cl-effects on crop plant.The effects of different concentrations of Cl-(0,25,50,75,100 and 200 mmol/L) on plant growth,photosynthetic pigment,photosynthesis traits and water use efficiency in canola(Brassica napus L.) seedlings for 9 and 18 days were investigated.The results show that the dry matter accumulation rates are increased under the 25-100 mmol/L Cl-treatments for 9 and 18 d,and the highest values are under the treatment of 50 mmol/L Cl-,while the plant dry matter accumulation rate is decreased significantly under the 200 mmol/L Cl-.The chlorophyll(Chl) contents are ascended in first and descended under different concentrations of Cl-treatment for 9 d,and the highest values are under the treatments of 100 mmol/L Cl-.Nevertheless,for 18 d,the Chl contents are decreased under the Cl-treatments,and the more the applied Cl-concentration is,the more the decrease is.The chloride concentrations of canola leaves are markedly increased under the Cl-treatments.Compared with the control,the Cl-contents in canola leaves are increased by 814%,805%,1043%,1083% and 2157% for 9 d and by 745%,1270%,1340%,1900 and 3386% for 18 d,under 25,50,75,100 and 200 mmol/L Cl-treatments,respectively.Apart from Ci under the Cl-treatments for 18 d,canola leaves are able to maintain high values of Pn,Gs,Ci,and Tr under 25-100 mmol/L Cl-treatments.For 9 and 18 d,Pn both achieve the highest values under the 25 mmol/L Cl-treatment,and are increased by 12% and 13% compared with each control,respectively.Pn,Gs,Ci and Tr of canola leaves are significantly decreased under the 200 mmol/L Cl-treatment for 9 and 18 d.As Cl-concentration increased,WUE is descended in first and ascended followed.However,Ls is descended in first and ascended followed under the Cl-treatments for 9 d,and increased gradually for 18 d.Under 200 mmol/L Cl-,Ls of canola leaves are increased by 48% for 9 d,and by 76% for 18 d.Correlation analysis indicates that for the 9 d treatments,the DMAR of canola is insignificantly related to root/shoot,Chl content,Cl-content and Ls,very negatively related to WUE,positively related to Gs,and very positively related to Pn,Ci and Tr,respectively.For 18 d treatment,the DMAR of canola is insignificantly related to root/shoot,Chl content,Cl-content,Ls and WUE,positively related to Gs,and very positively related to Pn,and Tr,respectively.Our results implicate that photosynthesis and transpiration of canola seedlings are significantly increased under the low Cl-treatments,and thus make a contribution to plant growth,while the high Cl-treatments show opposite situations,and the photosynthetic limitation is mostly due to stomatal limitation.Pn,Gs and Tr can be regarded as value indexes of chloride adaptation of canola growth.