Abstract: Photosynthetic pigments gas exchange， chlorophyll （Chl） fluorescence， and the activities of antioxidant enzymes and metal elements were characterized from the apical fully expanded seedling leaves in Brassica rapa L. ssp. rapifera at five\|leaf and one\|heart stage grown with either complete or Fe\|deficient nutrient solution for 20 days. The results showed that Fe\|deficiency severely decreased the content of total chlorophyll， chlorophyll a， chlorophyll b， and the ratio of Chl a/b， while the content of carotenoid （Car） was not affected. Due to the decline of photosynthetic pigment content， Fe\|deficiency stress reduced net photosynthetic rate （Pn）， gas conductance （Gs） and transpiration rate （Tr）. However， the intercellular CO2 concentration （Ci） was markedly higher than that of control plants， demonstrating the decreased photosynthetic capacity was caused by the limitation of non\|stomatal factors. Besides， Fe\|deficiency stress also greatly decreased the maximal photochemistry of PSⅡ （Fv/Fm）， the effective quantum yield of PSⅡ （photochemical quenching coefficients）， while non\|photochemical quenching coefficient （NPQ） highly increased as compared with that in control plants. The activities of superoxidase （SOD） and catalase （CAT） in Fe\|deficient plants decreased markedly， while the activity of peroxidase（POD） slightly increased; the content of malondialdehyde （MDA） was highly increased， suggesting the higher degree of lipid peroxidation. In addition， the biomass of shoot and root was decreased， but the ratio of shoot to root was not changed significantly. Moreover, the content of Fe in Fe\|deficient plants were markedly reduced, while the content of Mn and Mg were not changed, the content of Cu and Zn were significantly increased as compared with the control plants. Taken together， Fe\|deficiency stress caused great decrease in content of photosynthetic pigments， Pn， Fv/Fm， photochemical chemistry and the activity of antioxidant enzyme, and therefore an increase in MDA content and finally decreased biomass.

Key words: Brassica rapa L., Fe\, deficiency, photosynthetic characteristics, antioxidant enzymes