Studies On The Photosynthetic Physiological Characteristies And Drought Tolerance Of Three Cultivars Of Trachelospermum

In thie research, the photosynthetic physiological characteristics and drought tolerance for threecultivars of Trachelospermum (Trachelospermum asiaticum ‘Ougonnishiki’, Trachelospermumjasminoides ‘Variegatum’ and Trachelospermum. jasminoides var. variegate) were studied. The resultsshowed that:(1) On the basisi of Light-response curve of photosynthesis, the photosynthesis capability ofthree cultivars of Trachelospermum was: Trachelospermum asiaticum ‘Ougonnishiki’＞Trachelospermum jasminoides ‘Variegatum’＞Trachelospermum. jasminoides var. variegate. But theabilities of using light and light adaptation range of three cultivars of Trachelospermum were not thesame with the photosynthesis capability, the sequence was: Trachelospermum asiaticum‘Ougonnishiki’＞Trachelospermum. jasminoides var. variegate＞Trachelospermum jasminoides‘Variegatum’. And the light energy conversion efficiency of three cultivars of Trachelospermum was:Trachelospermum asiaticum ‘Ougonnishiki’＞Trachelospermum jasminoides ‘Variegatum’＞Trachelospermum. jasminoides var. variegate. The curves diurnal variation of Pn of three cultivars ofTrachelospermum had distinct photosynthetic depression and presented two peaks. And the change ofTr and Cond was similar to the Pn, but the Ciwas opposite. Three cultivars of Trachelospermum haddifferent WUE, its sequence of them was Trachelospermum asiaticum ‘Ougonnishiki’＞Trachelospermum. jasminoides var. variegate＞Trachelospermum jasminoides ‘Variegatum’. Theinterrelation between the net photosynthetic rate of three cultivars of Trachelospermum and thephysiological and ecological factors is not same.(2) Under drought stress, on the basisi of the changes of physiological and biochemicalparameters for three cultivars of Trachelospermum, the results indicated that: the leaf water potentialand the content of chlorophyll of three cultivars of Trachelospermum were fallen, the relativeelectric conductivity and the content of MDA increaseed. However the activity of SOD and POD, thecontent of soluble protein showed “first increased and decreased afterwards” with the intensificationof drought stress.(3) Under drought stress, on the basisi of the changes of chlorophyll fluorescence parameters forthree cultivars of Trachelospermum, Fo and qN increased with the intensification of drought stress.However, Fm, Fv/F, Fv/Fm, Y, ETR and qP decreased. (4) On the basisi of the parameters changes and the chlorophyll fluorescence parameters, Withthe subordinate function method the drought-tolerance ability of three cultivars of Trachelospermumunder drought stress condition have been evaluated. The results are as following: Trachelospermum.jasminoides var. variegate＞Trachelospermum jasminoides ‘Variegatum’＞Trachelospermumasiaticum ‘Ougonnishiki’.