Chin J Plan Ecolo ›› 2006, Vol. 30 ›› Issue (5): 827-834.DOI: 10.17521/cjpe.2006.0105

• Research Articles • Previous Articles     Next Articles

EFFECTS OF SEAWATER ON PHOTOSYNTHESIS AND CHLOROPHYLL FLUORESCENCE IN HELIANTHUS TUBEROSUS SEEDLINGS IN DIFFERENT REGIONS

LONG Xiao_Hua; LIU Zhao_Pu*; JIANG Yun_Fang; CHEN Ming_Da; WANG Lin   

  1. College of Resources and Environmental Sciences , Nanjing Agricultural University, Nanjing 210095, China
  • Online:2006-09-30 Published:2006-09-30
  • Contact: LIU Zhao_Pu

Abstract:

Background and Aims Growing plants that are tolerant to saltwater is an option for use of coastal mudflats and application of seawater. 
Methods Pot experiments were carried out to study the effects of the seawater on photosynthesis and chlorophyll Ⅱ fluorescence of Helianthus tuberosus seedlings from three different regions, Yancheng (YC), Wuwei (WW), and Yantai (YT). Three different concentrations of seawater were applied: 0 (CK), 15%, and 30% seawater. 
Key Results Fresh and dry weights of roots and shoots of seedlings decreased with increasing seawater concentrations for all regions, but less at YC. Net photosynthetic rate (Pn), transpiration rate (Tr), water use efficiency (WUE), stomatal conductance (Gs), and stomatal limitation (Ls) decreased with increasing seawater concentration for all regions; however, intracellular CO2 (Ci) increased with increasing seawater concentration. The Pn and  Tr were the highest for YC, whereas WUE and Ci were lower and Gs and Ls were higher than those for WW and YT with the 15% seawater treatment. Minimal fluorescence (Fo), maximum fluorescence (Fm), variable fluorescence (Fv), stable fluorescence (Fs), difference between Fs and Fo (ΔFo), PSⅡ potential fluorescence efficiency (Fv/Fo), and PSⅡ maximum fluorescence efficiency (Fv/Fm) all decreased with increasing seawater concentration. Values of Fm, Fv, Fs, andFv/Fo were the highest for YC. Electronic transfer rate ( ETR), photochemical quench (qP), and photochemistry rate of YC leaves changed slightly. Compared to the controls, values for WW and YT all decreased markedly with 30% seawater and were lower than for YC. The PSⅡ actual fluorescence efficiency (ΦPSⅡ) changed differently with different treatments. TheΦPSⅡfor YC and WW was the highes with 15% seawater than other seawater concentration, andΦPSⅡfor YT was highest with CK. The Chlacontents all decreased and Chlb contents changed slightly with increasing seawater concentration. The ratio of Chla and Chlb for WW and YC deceased with increasing seawater concentration, and the ratio for YT changed slightly with the 0 and 15% seawater treatments. 
Conclusions Seawater suppressed the growth, photosynthesis, and chlorophyllⅡfluorescence of H. tuberosus seedlings, and effects increased with increasing seawater concentration. Seedlings grown in the YC region were less affected by seawater than those in the WW and YT regions.