| Guadua amplexifolia is a big-sized cluster bamboo which origins from South America with a lot of good characters, such as high biomass, good mechanical properties, particular culm form and so on. It has been introduced to Hua'an Bamboo Botanical Garden in Fujian Province, 2002. In order to extend utilization, we determined its photosynthetic physiological indexes, evaluated its growth status and effect of environmental factors on growth. In addition, we discussed its suitable condition in temperature, soil water content and soil salt content by pot experiment. The main conclusions are as follows:(1) Both diurnal variation of Pn and Tr were two-peak curves in different season, and more evident in Spring and Summer. Daily mean Pn and Pnmax in Spring and Summer are higher; in Autumn, low RH was the vital impact factor on Pn; low temperature was the important disadvantage to Pn in winter, both Pn and AQY were lower than other seasons evidently. Cold had decreased the photosynthetic capacity of G. amplexifolia, but to keep positive Pn at certain level was important for its survival.(2) When daily minimum temperature above 9℃, G. amplexifolia had vigorous metabolism without evident cold injury; when reached to 9℃, the ratio of free water to bound water decreased and metabolic activity declined; 3℃slight browning at leaf tips, and values of physiological indexes reached maximum, bamboo with serious injury; when daily minimum temperature reached -2℃, all leaves withered and values of physiological indexes reached minimum in the experiment, then after 6 days with daily minimum temperature below 3℃, the branches and top culms withered. So we take -2℃as its limitied low temperature.(3) When relative soil water content (RSWC) in 60%～70%, Pn and Tr decreased with Cond declined, but the Pn and Tr keep higher values and without other stress responses; in 30%～40% 20 days, electrolyte leakage and MDA content increased, but the main reason for decrease of Pn was stomatal limitation; 20-day continuous drought, the RSWC reached 12.8%, the main reason for decrease of Pn was non-stomatal limitation, photosynthetic organs serious damaged, and chlorophyll concentration declined evidently, photosynthetic rate below respiration rate and Pn became negative. After 20-day waterflooding, photosynthetic physiological indexes declined slightly but not evidence injury; after 30 days, half of leaves became yellow, electrolyte leakage increased, MDA and free proline content increased evidently, chlorophyll concentration declined. So we thought that this bamboo grew well in 80%～90% RSWC, can endure 60%～70% RSWC, was unsuitable to grow in 30%～40% and lower RSWC. Water out time should not be over 30d.(4) There were not evidence impact on Pn and Tr of bamboo exposed to 0.10% salinity; 0.20% and higher salinity can make Pn and Tr decrease evidently. The main reason for decrease of Pn was stomatal limitation in early stage and non-stomatal limitation later. The chlorophyll content also decreased evidently exposed to 0.20% and higher NaCl. Leaf-abscission rate and membrane permeability of plant exposed to 0.30% and higher salinity after 40-days were both over 50%, antioxidant enzyme activities lower than CK; but in plants exposed to 0.20% and lower concentration of NaCl, the antioxidant enzyme activities were higher than CK, MDA content were lower, the membrane permeability was lower than 50%, so 0.20% salinity can effected the photosynthetic physiology and chlorophyll content, and 0.30% was the limited salinity for G. amplexifolia.
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