Abstract: Effects of partial rootzone drying on photosynthetic pigment, photosynthesis and chlorophyll fluorescence of the grape cuhivar‘Malvasia’grafted on different rootstocks were studied by simulating soil boxes with three treatments, controlled alternating irrigation for half of rootzone(AI),controlled fixed irriga- tion for half of rootzone(FI),and conventional irrigation for whole root zone(CK).The result showed that the contents of Chl. a, Chl. b and Car. of M/420A, M/3309C and M/110R decreased slightly under AI than under FI. Different decreasing extents of the three pigments contents were also found in different cuhivar/root- stocks with two treatments. Pn of M/420A, M/3309C, and M/110R decreased slightly while Tr and Gs de- creased significantly with the amount from 41.1% to 56. 1% under AI, which increased the water use efficien- cy(WUE)significantly. WUE of M/3309C was 1.71 times of CK, while that of M/420A and M/110R were 1.36 and 1.66 times of CK respectively. Pn, Tr and Gs of three combinations decreased significantly under FI, with the amounts of M/3309C at 54.9%, 57%, and 80.4%, M/110R at 36. 3%, 51.3%, and 60. 5% respectively. WUE of M/420A, M/3309C and M/110R were 1.18, 1.05 and 1.31 times of CK respectively. No great differences was found in the chlorophyll fluorescence parameters of M/420A, M/3309C and M/110R in CK and AI when it comes to be obvious under FI. The Fv/Fo, Fv/Fm andΦPSⅡof 3 combinations de- creased significantly which the M/3309C decreased by 32. 1%, 13.5% and 25.7%, respectively, the M/ 420A decreased by 26. 4%, 12.3% and 23.7%, respectively, the M/110R decreased by 19.5%, 5.9% and 15.4%, respectively, which suggested that different effects on the same cultivar were significant among different rootstocks.

Key words: Grape, Rootstock, Partial Rootzone drying, Photosynthesis, Chlorophyll fluorescence, Alternating irrigation