Photosynthesis and antioxidant enzyme activity in breadfruit, jackfruit and mangosteen in Southern Yunnan, China

The Xishuangbanna Prefecture (21 degrees 09'-22 degrees 36' N; 99 degrees 58'-101 degrees 50' E) in southern Yunnan is one of the major growing areas for tropical crops in China. Daily temperature in Winter is about 8 degrees C lower that in Summer. The effects of season on photosynthesis and antioxidant enzyme activities were studied in the tropical fruit tree species Artocarpus altilis (breadfruit), A. heterophyllus (jackfruit) and Garcinia mangostana (mangosteen), growing in an open site. In August 2002 and January 2003, maximum net CO2 assimilation was 17.1 +/- 0.3 mu moles m(-2) s(-1) (mean +/- SE) and 10.7 +/- 0.5 in breadfruit; 11.7 +/- 0.2 mu moles m(-2) s(-1) and 10.9 +/- 0.6 in jackfruit; and 8.6 +/- 0.1 mu moles m(-2) s(-1) and 6.3 +/- 0.4 in mangosteen, respectively Concentrations of chlorophyll were lower in mangosteen and breadfruit in January than in August, while in January, photo-inhibition was evident in mangosteen and breadfruit by changes in leaf chlorophyll fluorescence. Concentrations of malondialdehyde (a product of membrane lipid peroxidation), carotenoid to chlorophyll ratios, and the activities of the antioxidant enzymes superoxide dismutase, catalase and peroxidase were higher in January than in August, in all species, especially the antioxidant enzyme activities in jackfruit. Moreover, in both August and January, mangosteen suffered severe mid-day photo-inhibition. These results indicate that jackfruit is chilling tolerant, breadfruit is chilling sensitive, and mangosteen is chilling and high-light intensity sensitive. Breadfruit and mangosteen do not appear to be suitable crops to grow outdoors in southern Yunnan, China.