Abstract: Under hydroponic culture， effects of high root\|zone temperature， high air temperature and the above temperature interaction （overall high temperature） on relative chlorophyll content （SPAD value）， chlorophyll fluorescence and photosynthesis parameters in leaf， the content of malondiadehyde （MDA）， proline， soluble protein and total sugar of “Wuyexiang” towel gourd rootstock grafted seedlings and self\|rooted cucumber seedlings in leaf and root were studied. Towel gourd rootstock grafted seedlings showed higher SPAD values， excitation energy capture efficiency of photosystem （PSⅡ） reaction center （Fv′/Fm′）， actual photochemical efficiency of PSⅡ （ΦPSⅡ）， leaf net photosynthetic rate （Pn）， transpiration rate （Tr） and photochemical fluorescence quenching coefficient （qP） than self\|rooted seedlings. And the former ones in roots had lower MDA content and higher proline content than the latter ones. The contents of soluble protein and total sugar in leaf and root also changed under the above three treatments with different rootstocks. The results indicated that grafting could relieve the heat stress of cucumber in some extent by changing the content of some substances in roots and leaves under different heat treatments.

Key words: cucumber, rootstock grafting, chlorophyll fluorescence parameters, photosynthesis parameters, osmotic regulation substances