| Ornamental grass is a new garden plants in recent years. Because of its wide species, high ornamental value, easy reproduction, simple maintenance and manage-ement of the environment to adapt to a wide range, therefore have a broad application prospects garden and strong market demanding. At present the study on ecological habits of ornamental grasses is small and not systematic, lead to lack of scientific basis on its introduction and application, and unfavorable on its industrial production and garden promotion, therefore, urgent need to carry out evaluation studies on ecological adaptability of ornamental grass. The Yangzijiang middle and lower region have long time high-temperature in summer, and beyond the optimum temperature of the atmospheric temperature extremes, because select suitable heat-resistant ornamental grass species of this region is necessary. Ophiopogon planiscus ’Nigrescens’, Ophiopogon variagata, arex muskingumensis, Carex. Buchanani, Carex elala, Miscanthus sinensis ’Zebrinus’, Miscanthus sinensis ’Variegatus’, Reineckea carnea(Andr.) kunth, Miscanthus Sinensis, Imperatac ylindrica ’RedBaron’ Chasmanthium latifoliu were used as materials of this study. By comparing cell membrane stability of leaf of eleven ornamental grasses then preliminary identifies different types of ornamental grass heat resistance. Combined with physiological changes during the over-summering in field observations, comprehensive evaluation of various types of ornamental grass in Nanjing region, and select heat-resistant species. On this basis, select a different four kinds of heat resistant ornamental grass are used to study its physiological responses during natural heat and the rainy season, artificial heat and the rainy season,revealing the physiological mechanism of its heat-resistant. This study will provide11kinds of ornamental grass in the Nanjing area to provide a scientific basis for the application of its industrial production to provide technical support.Cell membrane stability of leaf of eleven ornamental grasses in the different water bath temperature was measured by electrical conductivity method. Through the Logistic equation to determine the semi-lethal temperature and then identify different types of ornamental grass heat resistance. The results showed that O. planiscus ’Nigrescens’,I. cylindrica ’Red Baron’ and C. latifoliu had the strongest heat tolerance; then it comes to C.muskingumensis, C. buchananii and M. sinensis;while R. carnea (Andr.) kunth and O. variagata, C. elala were weak in heat tolerance; and M. sinensis ’Zebrinus’ and M. sinensis ’Variegatus’ were the weakest.TakingO.planiscus ’Nigrescens’,O.variagata,C.muskingumensis,C.Buchanani,Carexelal a, M. sinensis ’Zebrinus’,M. sinensis ’Variegatus’,R. carnea(Andr.)kunth,M sinensis,I. cylindrica ’RedBaron’,C.latifoliu as objects of study. During May to August, determine several physiological indices per month of ten ornamental grasses.The result showed that the content of chlorophyll increased first and decreased soon;During Jul to Aug,the content of chlorophyll decreased of ten ornamental grasses, but O. planiscus ’Nigrescens’ and C. latifoliu had most lowly decreased; R.. carnea (Andr.) kunth,M. sinensis ’Zebrinus’ and M. sinensis ’Variegatus’ had higestly decreased; the content of proline increased first and decreased soon,O.planiscus ’Nigrescens’,I. cylindrica ’Red Baron’ and C. latifoliu had lowestly increased while R. carnea (Andr.) kunth, M. sinensis ’Zebrinus’,C. elala and M. sinensis ’Variegatus’ had most highly increased during Jul to Aug; the activities of SOD and POD decreased first and increased soon, R. carnea (Andr.) kunth, M. sinensis ’Zebrinus’,C. elala and M. sinensis ’Variegatus’ had biggest change range,O. planiscus ’Nigrescens’,I. cylindrica ’Red Baron’,C. muskingumensison’ and C. latifoliu had smallest change range,while M. Stenosis, C. muskingumensis and C. Buchananii was in the range between the biggest and smallest. Combination of cell membrane stability of leaf and thus arrived O. planiscus ’Nigrescens’, I.cylindrica ’Red Baron’ and C. latifoliu had the strongest heat tolerance, then it comes to M. stenosis, C. muskingumensis and C. Buchananii, R. carnea (Andr.) kunth, M. sinensis ’Zebrinus’,C. elala and M. sinensis ’Variegatus’ were weak in heat tolerance.Taking the strongest heat tolerance of O. planiscus ’Nigrescens’, medium heat tolerance of C. muskingumensis and C. Buchananii, weak heat tolerance of C. elala as experimental material, artificial simulation of rainy season and high temperatures, analysis of four kinds of ornamental grass physiological activity changes. The results showed that during the simulated rainy season, the content of chlorophyll decreased in first five days, and then increased, the content of chlorophyll of O. planiscus ’Nigrescens’,C. muskingumensis, C. elala and C. Buchananii on the treatment day of20respective is the treatment day of5of1.25,1.19,1.01and1.43times; Proline content of O. planiscus ’Nigrescens’, C. elala,C.Buchananii and C. muskingumensis were increased gradually, and Proline content on the treatment day of20compared with treatment at day0increased 16.38%,10.33%,12.39%and14.04%respectively;Soluble protein content of O. planiscus ’Nigrescens’,C. elala,C. Buchananii andC. muskingumensis were increased gradually, and soluble protein content on the treatment day of20respective is the treatment day of0of2.59,1.59,8.55and4.92times; MDA were increased gradually, and MDA content on the treatment day of20respective is the treatment day of0of1.24,1.44,1.26and1.38times; he activities of SOD and POD increased first and decreased soon, and the activities of SOD and POD from high to low was O. planiscus ’Nigrescens’,C. muskingumensis, C. Buchananii andC elala. Simulation of high-temperature stage, with the treatment of high temperature, the content of chlorophyll of O. planiscus ’Nigrescens’,C. muskingumensis, C. Buchananii and C. elala. increased first and decreased soon, chlorophyll content on the treatment day of30compared with treatment at day20increased18.36%,18.17%,19.84%and19.99%respectively; Proline content were increased gradually with the treatment of high temperature, and proline content on the treatment day of30respective is the treatment day of20of1.39,1.73,1.64and1.87times; Soluble protein content of20-23days decreased,23-32day decreased, and soluble protein content on the treatment day of32respective is the treatment day of23of2.31,1.60,1.58and1.56times; MDA content decreased slightly first and increased; the activities of SOD and POD increased first and decreased soon, and the activities of SOD and POD from high to low was O. planiscus ’Nigrescens’,C. muskingumensis, C. Buchananii and C. elala.Taking the strongest heat tolerance of O. planiscus ’Nigrescens’, medium heat tolerance of C. muskingumensis and C. Buchananii, weak heat tolerance of C. elala as experimental material, during natural rainy season and high temperatures period,analysis of four kinds of ornamental grass physiological activity changes. The results showed that during the rainy season, the content of chlorophyll decreased first and then increased, the highest chlorophyll content compared to lowest chlorophyll content,the strong heat-resistant ornamental grass increased higher than the weak heat tolerance ornamental grass; Proline content of O. planiscus ’Nigrescens’,C. elala, C. Buchananii and C. muskingumensis were increased gradually, and highest proline content compared with lowest proline content of1.16,1.51,1.28and1.27times; the activities of SOD and POD increased first and decreased soon, and the activities of SOD and POD from high to low was O. planiscus ’Nigrescens’, C. Buchananii, C. muskingumensis andC. elala. Natural of high-temperature stage, with the treatment of high temperature, the content of chlorophyll of O. planiscus ’Nigrescens’,C. muskingumensis, C. Buchananii and C. elala. decreased, the strongest heat tolerance ornamental grass decreased lowest, then the medium heat tolerance ornamental grass,the weak heat tolerance ornamental grass decreased largest; proline content were increased, proline content reached the highest value at Aug.4and reached the lowest value at July19, highest value respective the lowest value of1.19,1.25,1.59and1.61times; the activities of SOD and POD increased first and decreased soon, and the activities of SOD and POD from high to low was O. planiscus ’Nigrescens’, C. Buchananii,C. muskingumensis and C. elala.Comprehensive analysis of artificial simulation and field observation under rainy conditions and high temperatures of the physiological responses of four ornamental grasses, which can show that chlorophyll content increased during rainy conditions,this can induce the photosynthetic function of leaf is increased, high content of soluble protein showed that nitrogen metabolism improve, Above all conducive to the growth of ornamental grass; In high temperature,the strongest heat tolerance ornamental grass of chlorophyll decline smaller than the weak heat tolerance ornamental grass; Proline content of leaf compared to the treatment day of0, the strongest heat tolerance ornamental grass of proline content increased lower than the weak heat tolerance ornamental grass; MDA content increased with the treatment of high temperature, and the strongest heat tolerance ornamental grass increased first, than the weak heat tolerance ornamental grass; The activities of SOD and POD of the strongest heat tolerance ornamental grass was higher than the relative value of the weak heat tolerance ornamental grass. |
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