Effects of calcium ion concentration on photosynthetic and fluorescence characteristics of grafted cucumber seedlings under NaCl stress
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DOI:10.7606/j.issn.1000-7601.2018.04.28
Key Words: grafted cucumber seedlings  concentrations of Ca2+  photosynthetic characteristics  fluorescence characteristics
Author NameAffiliation
LIU Xin School of Agriculture Ningxia Uniersity, Yinchuan, Ningxia, 750021 ,China 
YOU Shi-yao School of Agriculture Ningxia Uniersity, Yinchuan, Ningxia, 750021 ,China 
ZHOU Hai-xia School of Agriculture Ningxia Uniersity, Yinchuan, Ningxia, 750021 ,China 
QI Juan-xia School of Agriculture Ningxia Uniersity, Yinchuan, Ningxia, 750021 ,China 
ZHANG Xue-yan School of Agriculture Ningxia Uniersity, Yinchuan, Ningxia, 750021 ,China 
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Abstract:
      In order to solve the problems of serious protected soil salinization in Ningxia and increasing salt damagetocrop, the grafted cucumber seedlings were used as experimental materials, to explore the effects of different concentrations of exogenous CaCl2 on photosynthetic and fluorescence characteristics of grafted cucumber seedlings under 100 mmol·L-1 NaCl stress. The results showed that,net photosynthetic rate (Pn), stomatal conductance (Gs) of cucumber seedlings declinedand, transpiration rate (Tr) and intercellular CO2 concentration (Ci) declined at first and then increased,under the treatment of gradient calcium concentration, 10 mmol·L-1 Ca2+ had significantly increased plant water use efficiency. On the 11 days of treatment, The initial fluorescence showed an rising trend in all but 10 mmol·L-1 Ca2+ treatment. the lowest Fo value of 10 mmol·L-1 Ca2+ treatment was 787.4, maximum fluorescence (Fm) was second only to CK, exogenous 10 mmol·L -1 Ca2+ can significantly increase the maximal photochemical efficiency (Fv/Fm), which were 17.69 times, 1.33 times, 1.66 times, 2.82 times and 1.22 timesofthe other 5 Ca2+ concentration treatments. On the 11 days of treatment, the qP values of all treatments showed an rising trend, the10 mmol·L-1 Ca2+ treatment with qP of 0.677 wasthe closest to CK. After different concentrations of CaCl2 treatment, there was no significant difference in non photochemical quenching coefficient (qN) between the treatments. The photosynthetic electron transfer rate (ETR) from 10 mmol·L-1 Ca2+ treatmentwas significantly higher than that from other treatments. In summary, exogenous 10 mmol·L-1 Ca2+ could significantly alleviate thesalt damage to cucumber seedlings and improve its salt tolerance.