Evaluation The Heat Resistance Of Seedling Wild Dactylis L.

Dactylis glomerata ssp. Glomerata L. is one of the most important members of the Gramineousgenus Dactylis, and as a important forage grass is widely cultivated in the world due to high forageyield, good quality, and stresses tolerance. There is abundant native D.glomerata germplasm intemperate climates zone in china, and many excellent germplasm have been domesticated. As a kind ofcool-season forages grass, high temperature is a major abiotic stress that limits D.glomerata growth andproductivity in the middle and lower reaches of the Yangtze River. However, there were few researchesabout heat resistance evaluation reports in previous studies. Shennongjia is separated natural watershedof the north-south climatic zone in our country, and there are abundant native D.glomerata germplasmresources in this area. In order to better development and utilization of the resources, the fieldproduction performance and artificial simulation of seedling to assess combined heat resistantidentification were applied to evaluation high temperature resistance of four D.glomerata materials.Among those D.glomerata materials, cv Banbiyan and cv Shenglongjia were collected fromShennongjia with heat resistant breeding, and cv Chuandong and cv Baoxing were widely used cultivars.The main results were as follows:1. Three years of field experiment showed that cv Banbiyan is performed very well, which withthe turn green early, full of powerful tillering, higher plant, higher leaf-stem ratio, higher fresh（2522.59kg/667m2）and dry（518.13kg/667m2）weight.2. Seedling responses of four D.glomerata cultivars to high temperature stress were studied under20℃/10℃、25℃/15℃、30℃/20℃、35℃/25℃、40℃/30℃、45℃/35℃treatments. The relativeelectrolyte leakage, chlorophyll content, proline content and superoxide disproportionation (SOD)activity were measured in the leaves. The relationship between the various index change andinflorescences heat resistance were analyzed to compare the heat resistance between different materials.The results induced that with the increase of temperature, the proline content and relative electrolyteleakage are first showed a trend of decreasing and then increasing; while the SOD enzyme activity isfirst increasing and then decreasing. Distinct physiological responses in terms of different physiologicalindicators were induced that cv Chuangdong with the best resistance.3. D.glomerata seedlings semi-lethal temperature refers to under high temperature stress, D.glomeratawas appeared inflorescences, and when the temperature continues to raise the damage taken by theseedlings will not resume. Seedling leaf segments of four D.glomerata species were used to study theheat tolerance by an electrical conductivity method, in combination with a Logistic equation to ascertainthe semi-lethal high temperature by fitting the cell injury rate curve. All of that help us to explore a setof more scientific heat resistance evaluation system suitable for forage.