Abstract This paper studied the effects of NaCl（150 mmol · L-1）treatment on germination，seedling
growth and related gene expression of 4 melon cultivars（thin-skinned melon IVF05，IVF89 and thick-skinned
melon IVF117，IVF303）．The results showed that under NaCl stress，the growth indexes of thin-skinned
melon IVF89 were severly inhibited. Its germination rate，germination index，radicle length and hypocotyl
length were decreased by 35.00%，76.24%，46.71% and 39.27%，respectively. While，the growth indexes of
thick-skinned melon IVF303 were least inhibited. Its germination rate did not decrease obviously，germination
index，radicle length and hypocotyl length were decreased by 46.52%，34.86% and 23.08%，respectively.
NaCl stress could increase the activities of antioxidant enzymes superoxide dismutase（SOD），peroxidase
（POD）and catalase（CAT）in the leaves of melon seedlings，and increased the contents of free proline（Pro），
malondialdehyde（MDA）and soluble protein. The net photosynthetic rate（Pn），transpiration rate（Tr），
stomatal conductance（Gs）and SPAD values of these 4 melon cultivar seedlings were significantly decreased．
The Pn of IVF05，IVF89，IVF117 and IVF303 were decreased by 64.44%，69.62%，61.23% and 60.00%，
respectively. And the expression of key enzyme genes in Calvin cycle（CmRubisco，CmPGK and CmFBPase）
of the 4 cultivars was significantly down-regulated，while the expression of CmPRK was up-regulated. The
expression of salt-tolerant genes（CmSOS1，CmNHX1，CmHKT1 and CmGnT）was up-regulated. Among
them，the gene expression of cultivar IVF303 had the largest range of up-regulation. These 4 melon cultivars
were divided into 3 categories by principal component analysis，correlation analysis and cluster analysis. IVF05
and IVF89 were of salt-sensitive type，IVF117 was of moderate salt-tolerant type，and IVF303 was of strong
salt-tolerant type．
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Received: 02 April 2019
Published: 15 September 2019
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