Abstract:

Net photosynthesis in assimilative shoot of C.arborescens Litv. rised gradually following with the increase on light intensity and light saturation point was higher. Net and ture photosynthesis and light saturation point were higher in summer than autumn. The results showed that C.arborescens Litv. is a sun ecotype plant and its assimilative shoot started decline in September.Net photosynthesis was significently decreased following with the gradual rising of temperature under saturation light, On the contrary, respiration tised, but changes of ture photosynthesis where little in those two seasons. These indicated that the decline of net photosynthesis was induced by the rising of respiration.there were many effects of drought on photosynthesis in a ssimilrtive shoot of C.arborescens Lity. Water potential declied gradually with the increase of treatment time. The change inclination of net photosynthesis, ture photosynthesis, respiration, photorespiration, light saturation point, light compensation point and chlorophyll content were similar to that of water pocential. Contrarily, Co₂ compensstion point was significently rised at saturation light, but, net photosynthesis can keep 58. 5% yet after 12 days.The plant was treated by the combination of drought and temperature. The change tendency of all aspects were similar to the effects of drought. though, the degree of damage was greater, however, the ture photosynthesis is yet. kept 41. 5%. It showed that except morphological constitution, physiological founction of the desert plant has wider adaptability to strong light, hight temperature and drought of environment.

Key words: Photosynthesis Respiration, Temperature, Drought, Calligorum Arborescens Litv,