Evaluation On Drought And High-temperature Resistance Of Ten Cultivas Of Osmanthus Fragrans

Osmanthus fragrans Lour. is a evergreen shrub or small tree of OsmanthusGenus(Oleaceae families), witch with luxuriant foliage. The flower of it is dense, andthe colour of flowers is rich. Sweet perfumes are diffused all around during floweringPeriod in O. fragrans. It is one of the top-ten traditional flowers in China.In order to elucidate the responses mechanism of O. fragrans subjected todrought and high-temperature stress. The field performance and leaf anatomicalstructure of10cultivars of O. fragrans were evaluated. The physiological andbiochemical responses of leaf were studied under different degree of drought and high-temperature stress. Comprehensive evaluation of drought and high-temperatureresistance of these10cultivars were conducted by using fuzzy subordination method.The results obtained may be used as important theoretical basis and reference inintroducing O. fragrans into higher latitude regions. The main findings are as follows:1. The survey on the dry heat resistance of O. fragrans. Dry heat hardiness of10cultivars of O. fragrans that growing under the natural environmental conditions wasevaluated during the period of serious dry-hot wind. The results showed that allcultivars of O. fragrans had a certain resistance to dry heat. The dry heat tolerance of10cultivars decreased in the order of O. fragrans ’Moye Dan’> O. fragrans’Huangchuan Jingui’> O. fragrans ’Juban’> O. fragrans ’Kuoye Zaoyin’> O.fragrans ’Xiaoye Sijigui’> O. fragrans ’Jiulong Gui’> O. fragrans ’Qingjian’> O.fragrans ’Zhusha Dangui’> O. fragrans ’Rixiang Gui’>O. fragrans ’Xiaohua Jin’.There were a few yellow spots on the leaf tip of the lightest injured cultivars. Therewere not phenomenon of plant death even in worst-affected cultivars.2. The observation and measure on the leaf organization structure and stomataldensity of ten cultivars of O. fragrans with optical microscope. The results showedthat the leaf tissue of O. fragrans ’Huangchuan Jingui’ was the maximum, the O.fragrans ’Xiaohua Jin’ is the minimum; the palisade tissue of O. fragrans ’Huangchuan Jingui’ was the thickness; the ratio of the palisade tissue and spongytissue (P/S), and the cell structure tightness (CTR) of O. fragrans ’Juban’ was themaximum; the cell structure tightness of O. fragrans ’Xiaohua Jin’ is the minimum;the stomatal density of O. fragrans ’Juban’ is the maximum.3. The experiment studied under artificial drought stress show that there was asignificant difference in the relative electrical conductivity, soluble protein content, theactivity of SOD and POD are extremely significant between different cultivars. Therewas a significant difference between different drought treatments too.4. The high-temperature resistance of these10cultivars were studied underartificial high temperature stress. The logistic equation was constructed based on therelationship between REC and temperature, then the semi-lethal temperature(LT50) wasdetermined. The results showed that LT50of O. fragrans ’Juban’ was up to53.23℃,and O. fragrans ’Xiaohua Jin’ was low as42.41℃. The analysis of variance showedthat there were a significant difference in relative conductivity and soluble proteincontent between different cultivars and temperatures; the difference of SOD and PODactivity between the different cultivars were also extremely significant; the differenceof POD activity between the different temperature treatments was significant, but thedifference of SOD activity between different temperatures had not difference.5. Comprehensive evaluation of drought resistance of10cultivars in O. fragranswas conducted by using fuzzy subordination method. The results showed that the orderof the ability for drought resistance of the10cultivars form strong to weak was: O.fragrans ’Huangchuan Jingui’> O. fragrans ’Kuoye Zaoyin’> O. fragrans ’Juban’>O. fragrans ’Zhusha Dangui’> O. fragrans ’Xiaoye Sijigui’> O. fragrans ’JiulongGui’> O. fragrans ’Qingjian’> O. fragrans ’Moye Dan’> O. fragrans ’Rixiang Gui’> O. fragrans ’Xiaohua Jin’.Comprehensive evaluation of high-temperature resistance of these10cultivarswas conducted by using fuzzy subordination method. The results showed that the heat-resisting ability of the ten varieties of sweet-scented osmanthus by the strong to theweak in order was: O. fragrans ’Huangchuan Jingui’> O. fragrans ’Qingjian’> O.fragrans ’Zhusha Dangui’> O. fragrans ’Xiaoye Sijigui’> O. fragrans ’Rixiang Gui’> O. fragrans ’Jiulong Gui’> O. fragrans ’Moye Dan’> O. fragrans ’Juban’> O.fragrans ’Kuoye Zaoyin’> O. fragrans ’Xiaohua Jin’.