Researches On Adaptability To Light And Soil And Physiological Response To Heat And Drought Stress Of Three Fan Flower Varieties

Using three Australian fan flower varieties Scaevola albida'Blue Ribbon', S. aemula 'Sunfan' and S. albida'Pink Ribbon' as materials, growth status under different sun light and soil conditions were first observed in this paper. Secondly, a three-factor experiment (three varieties; temperatures:35℃,40℃,45℃; treatment time:12h,24h,36h,48h) for heat stress and a two-factor experiment (three varieties; drought treatments:3d,5d,7d) for drought stress was designed respectively to research physiological and biochemical changes of these varieties under heat stress and drought stress, and then the changes of the content of leaf's relative water, chlorophyll, MDA, Pro, soluble protein and soluble sugar, leaf's relative conductivities, enzyme activity of SOD, POD and CAT. Main results were as following:(1) Plant height, crown width and chlorophyll content of Blue Ribbon without sun-shade were higher than those under half sun-shade. Plant height and crown width of Sunfan under half sun-shade were higher than those without sun-shade, while chlorophyll content of Sunfan without sun-shade was higher than that under half sun-shade. Plant height of Pink Ribbon under half sun-shade was higher than that without sun-shade, while crown width and chlorophyll content of Pink Ribbon without sun-shade were higher than those under half sun-shade.(2) Three varieties could grow normally in loam and clay soil. Plant height, width and chlorophyll content of Blue Ribbon and Pink Ribbon in loam soil were all higher in clay soil; for Sunfan, plant crown width in loam soil were larger than in clay soil, but no significant differences in plant height and chlorophyll content existed between the plants grown in loam soil and clay soil.(3) Under heat stress, leaf relative water content and chlorophyll content of three varieties all decreased; leaf relative conductivities of Blue Ribbon and Sunfan varied steadily in the whole test period, while that of Pink Ribbon increased rapidly in later period; the content of MDA in leaves ascended gradually, and the increasing amplitude of Blue Ribbon was the smallest.With temperature rising, Pro and soluble sugar content in leaves of three varieties increased. With the heat stress time prolonging, Pro content always increased, while soluble sugar content in leaves of the three varieties increased at first and decreased later. Under heat stress, soluble protein content in roots, stems and leaves of the three varieties all increased at first and decreased later.SOD activity in leaves and stems of three varieties all increased at first and decreased later; SOD activity in roots of Blue Ribbon and Pink Ribbon always decreased,while that of Sunfan increased at first and decreased later.POD activity in roots, stems and leaves of three varieties all increased at first and decreased later.With temperature rising, CAT activity in roots and stems of three varieties all increased at first and decreased afterwards; CAT activity in leaves of Blue Ribbon and Sunfan always decreased, while that of Pink Ribbon increased at first and decreased later. With the heat stress time prolonging, CAT activity in roots, stems and leaves of three varieties all increased at first and decreased afterwards.(8) Under drought stress, leaf relative water content and chlorophyll content of the three varieties decreased. MDA content in leaves of Blue Ribbon and Pink Ribbon increased at first and decreased afterwards, while that of Pink Ribbon always increased in the whole tests period.With the drought stress intensified, soluble proline content in leaves of Blue Ribbon increased at first and decreased later, while that of Pink ribbon and Sunfan always increased. Soluble sugar content in leaves of the three varieties increased at first and decreased later. Soluble protein contents in roots, stems and leaves of the three varieties all increased at first and decreased later. As drought stress time extended, SOD activity in leaves and roots of the three varieties increased at first and then decreased, while that in stems always decreased.As drought stress time extended, POD activity and CAT activity in roots, stems and leaves of the three varieties all increased at first and then decreased.