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Effects of salt stress on the seedling’s photosynthetic characteristics of different genotypes sweet potato.

QI Bing-jie1,2, WANG Ji-dong2, MA Hong-bo2, CHEN Jie2, ZHANG Yong-chun2, XU Yang-chun1**, CHANG Zhi-zhou2,3   

  1. (1 College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China; 2 Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Scientific Observation & Experiment Station of Farmland Conversation and Cultivation in Jiangsu, Ministry of Agriculture, Nanjing 210014, China)
  • Online:2012-12-10 Published:2012-12-10

Abstract: Taking the seedlings of 12 genotypes sweet potato as test materials, this paper studied their photosynthetic characteristics and plant growth under salt stress (0 and 85 mmol·L-1 of NaCl) for 20 days. As compared with the control, 85 mmol·L-1 of NaCl inhibited the growth of the seedlings. Of all the 12 genotypes, the “Zhezi No. 1”, “Xushu No. 18”, and “Xushu No. 22” were lesser impacted, while the “Yanshu 25” and “Langshu 7.12” were damaged more seriously. Under salt treatment, the leaf relative water content (RWC) of different genotypes sweet potato was above 75%, and no significant differences were found among the genotypes. The leaf chlorophyll content index (CCI), net photosynthetic rate (Pn), stomatal conductance (Gs), and instantaneous wateruse efficiency (iWUE) decreased under the treatment of salt. The “Zhezi No. 1” and “Xushu No. 18” had the highest values of CCI and Pn, but the Gs of “Zhezi No. 1” was greatly impacted by salt, with the salinity susceptibility index (SSI) being 22%. The “Yanshu No. 25” was sensitive to NaCl, and had lower SSI of CCI, Pn, and iWUE than the other genotypes. The main reason for the reduction in the photosynthetic rate of “Xushu No. 18”, “Chuan No. 211”, and “Zhezi No. 1” was stomatal limitation, but the three genotypes showed higher photosynthetic efficiency under salt stress. The other nine genotypes were of nonstomatal limitation, but their salt susceptibility differed. In terms of physiological and biochemical indices, the “Zhezi No. 1” and “Xushu No. 18” showed more tolerance against NaCl stress.