Germplasm Screening And Heat Resistent Evaluation Of Different Population Of Lolium Perenne

Heat stress is one of the main environmental factors limiting the growth of Lolium perenne.In production applications,heat-resistant Lolium perenne varieties can be used as turfgrass;heat-sensitive varieties are more suitable for use as a broadcast material in the transition zone.In this experiment,100 Lolium perenne germplasm resources collected from USDA-GRIN were used as materials to screen their main morphological characteristics,combining photosynthetic characteristics and chlorophyll fluorescence kinetic parameters,etc.The indicators were evaluated on the heat resistance of different Lolium perenne..germplasm resources.The main findings are as follows:(1)High-temperature treatment of 100 Lolium perenne germplasm resources resulted in a decline in the turf quality of Lolium perenne.Compared with the control group without high temperature treatment,The plant ID of the 10 groups of Lolium perenne germplasm resources with the smallest decrease in turf quality were:12,5,13,28,62,61,9,4,3,26.(2)With the increase of high temperature stress time,the electrolyte leakage rate of Lolium perenne germplasm resources increased gradually.The electrolyte leakage is an index reflecting the integrity of the cell membrane,and the smaller the value,the better the heat resistance.The experimental data showed that,compared with the control group,the plant ID of the 10 groups of Lolium perenne germplasm resources with the lowest increase in electrolyte permeability were 12,3,4,30,49,13,67,20.62,5.(3)After high-temperature treatment,the relative water content of plant leaves reflects the resistance of plant to high temperature stress.The smaller the relative water content of the leaves indicates the better the heat resistance of the plants.The results of this experiment showed that the plant ID of the 10 groups of Lolium perenne germplasm resources with the smallest decrease in leaf relative water content were 3,12,13,56,9,30,76,20,4,62.(4)The chlorophyll content of the Lolium perenne germplasm resources gradually decreased with the increase of the high temperature stress time.According to the experimental data,the plant numbers of the 10 groups of Lolium perenne germplasm resources with the smallest reduction were 13?4?5?12?62?9?20?3?28?37.(5)Determining the Fv/Fm of the plant can reflect the physiological response of the main photosynthetic system after high temperature treatment.With the progress of high temperature stress,the Fv/Fm gradually decreases.The plant numbers of the 10 groups of Lolium perenne germplasm resources with lowest reduction in Fv/Fm were 12,56,62,13,93,4,10,28,73,20.(6)With the development of high temperature stress,the osmotic potential of plants gradually decreased,and the plant numbers of the 10 groups of Lolium perenne germplasm resources with smallest decline were 5,67,3,32,9,12,53,33,27,35.(7)Root activity can directly affect the nutritional status and yield level of above ground parts.Therefore,the determination of root activity is beneficial to evaluate the heat resistance of plants.After high temperature treatment,the 10 groups of Lolium perenne germplasm resources with smallest decline in root activity were 5,13,10,28,4,62,12,32,3,59.(8)The PCA method was used to compare the turf quality,electrolyte leakage rate,relative water content,chlorophyll content,Fv/Fm,osmotic potential,and root activity of 100 Lolium perenne germplasm resources.We can find that the Lolium perenne germplasm resources have different adaptability to high temperature environment.The plant numbers of the five Lolium perenne germplasm resources with the best heat resistance were:12,4,13,3,5;the plant numbers of the five Lolium perenne germplasm resources with the worst heat resistance were:36,43,48,41,86.Five Lolium perenne germplasm resources with the best heat resistance can be used as key breeding objects.By studying the growth characteristics and heat resistance of perennial ryegrass,we obtained five heat-resistant Lolium perenne germplasm resources,which will contribute to the subsequent breeding of heat-resistant Lolium perenne varieties and the purpose of heat-resistant molecular mechanism of the Lolium perenne for future research.