Abstract: The effects of cytokinin（CTK）on growth, optical absorption and chlorophyll fluorescence kinetics parameters of ovary and fruit were studied in tomato ‘Bobcat’. A floral bud at the 7 d before flowering or a fruit at the 10 d after flowering was respectively sprayed with 600 and 800 mg · L-1 CTK. The CTK significantly promoted expansion of ovary and fruit. However, the vertical length of ovary of spraying the floral bud with 600 mg · L-1 CTK was obviously superior to 800 mg · L-1 CTK, and vertical length of fruit of spraying the fruit with 800 mg · L-1 CTK was obviously superior to 600 mg · L-1 CTK. The absorption coefficient（Abs）on the surface of the ovary could be in higher levers with 600 mg · L-1 CTK than 800 mg · L-1 CTK, but the Abs on the surface of the fruit could be in higher levels with 800mg · L-1 CTK than 600 mg · L-1 CTK. With the development of ovary and fruit, the maximum quantum yield of primary photochemistry of photosystem Ⅱ（Fv/Fm）， original quantum efficiencies（Q）and maximum electron transfer rat （ETRmax）decreased gradually，while the non-photochemical quench（qN） increased gradually. The CTK increased light absorption and utilization of ovary and fruit, which promoted the growth and development of fruit.

Key words: tomato, fruit, ovary, CTK, chlorophyll fluorescence