Abstract: The leaf chamber temperature was set to 22, 25, 28, 31 and 34℃ by Li-6400 portable photosynthesizer to simulate the local leaf temperature, the photoresponse curves of leaf photosynthetic characteristics of potato tuber were measured under the conditions of full water supply (soil water content remained at 80% field holding as control treatment) and drought (soil water content began to continue drought at 65% field holding) during the expanding stage of potato tuber, and the response characteristics of potato leaf photosynthetic characteristics to leaf chamber temperature under drought conditions were studied. The results showed that under adequate irrigation conditions, potatoes had greater photosynthetic potential at 25℃, and the utilization of low light was the strongest. Under 22℃, potato leaves had the strongest adaptation to light environment, and under 28℃, potato leaves had the best activity, while drought stress treatment significantly reduced the maximum photosynthetic capacity, low light utilization capacity and leaf activity of potato. With the increase of temperature, the net photosynthetic rate and stomatal conductance of potato leaves first increased and then decreased under adequate irrigation, and reached the maximum at 25℃, when the transpiration rate was the lowest and the water use efficiency was higher, indicating that under this temperature condition, potato showed strong water and air regulation ability and the strongest adaptability to the environment. Photosynthesis was more suitable at 25℃, followed by 22℃, under drought stress, the net photosynthetic rate of potato leaves was the highest, the transpiration rate was the lowest, the stomatal conductance was the highest, and the water use efficiency was the highest, which was the optimal temperature for potato adaptability under drought stress. Temperature higher than 31℃ was unfavorable for potato photosynthesis.

Key words: Potato, Photosynthesis, Drought stress, Temperature effect, Semi-arid zone