Photosynthetic Physiological Characteristics ofGazania rigensL. Under Drought Stress

To investigate the responses of photosynthetic physiological characteristics of Gazania rigens L. to drought stress, the changes of three cultivars ('Xingbai', 'XH' and 'Hongwen') photosynthetic values under drought stress were determined via LI-6400 portable photosynthesis analyzer (LI-COR, USA), and the relationships between photosynthesis and drought resistance of each cultivar were analyzed. The results showed that, three cultivars net photosynthetic rate ( Pn ), stomatal conductance ( Gs ), transpiration rate ( Tr ), and light use efficiency ( LUE ) value indicated the trend of decreasing gradually and there existed significant reduction in Pn and Gs values. There were extremely negative significant correlations between drought stress treatment days and Pn, Gs, Tr , water use efficiency ( WUE ) and LUE values. A small amount of leaves began to turn soft and yellow after drought stress treatment for 10 days, but they could recover to grow quickly after rehydration. The Pn values of 'Hongwen' decreased quickly and changed in a large range, so it had a poor resistance; the Pn values of 'Xingbai' decreased slowly and changed in a small range, so it had a strong resistance; while the changes of their hybrids -'XH' were between its parents. This research would provide a theoretical basis for gazania resistance cultivar breeding and application in landscape.