Study On Shade Tolerance Of Four Kinds Of Cold Season Turfgrass

The north side of the building and the space under the forest are mostly in a shady environment due to the blockage of sunlight.Using shade-tolerant turf grass for landscaping can quickly and effectively alleviate the shady greening problem,and the combination of trees,shrubs and turf grass forms a staggered landscape level,which can enrich the landscape effect and provide people with a beautiful living environment.Cool-season turfgrasses are commonly used in warm-temperate regions in northern China and have the advantages of high ornamental value.In the Yangtze River basin,high temperature in summer becomes a limiting growth factor for cool-season turfgrasses,and the temperature on the north side of buildings and in the understory space is relatively low,so studying their shade tolerance characteristics and screening cool-season turfgrasses that can adapt to the low light environment is an effective way to solve the problem of using cool-season turfgrasses in modern building environment and understory space in subtropical regions.Four cool-season turfgrasses: perennial ryegrass(Lolium perenne),tall fescue(Festuca arundinacea),purple fescue(Festuca rubra),and grass prairie grass(Poa pratensis)were selected as test materials and planted in pots with artificial shade nets.The experiment was conducted in four treatment groups: treatment 1: CK(0 % shade,full light),treatment 2: T1(25 % shade,light shade),treatment 3: T2(50 % shade,medium shade),and treatment 4: T3(75 % shade,heavy shade),to study the effects of different shade conditions on the growth and physiological indexes of the four coolseason turfgrasses and to conduct a comprehensive evaluation of shade tolerance.The results of the study were as follows The main results of the study are as follows:(1)Effects of different shading conditions on the growth of four cool-season turfgrassesThe plant height,tillering,density,and biomass of the four cool-season turfgrasses showed different degrees of changes after 30 d of shading treatment,with all four grasses reaching the maximum plant height,increasing the number of tillers,increasing the density,increasing the biomass of tall fescue and zoysiagrass,and decreasing the biomass of ryegrass and morning glory at 25 % shading.The growth of four cool-season turfgrasses was severely inhibited by 50 % shading and 75 % shading,and plant height,tillering and biomass were significantly reduced.(2)Effects of different shading conditions on physiological characteristics of four coolseason turfgrassesThe physiological characteristics of all four cool-season turfgrasses changed significantly after the shading treatment.25 % shading treatment showed little change in photosynthesis,increase in chlorophyll content,little change in antioxidant enzyme activity and chlorophyll fluorescence parameters.50 % and 75 % shading treatments showed a significant decrease in net photosynthetic rate,increase in intercellular CO2 concentration,decrease in stomatal conductance,decrease in transpiration rate of the four cool-season turfgrasses.,respiration rate decreased in ryegrass and tall fescue,the changes were not significant in zoysiagrass and early sagebrush,chlorophyll content decreased,the changes were relatively small in zoysiagrass,leaf water content increased,the increase was relatively small in zoysiagrass,antioxidant enzyme activity decreased,Fo values did not change significantly,Fm values,Fv/Fm decreased and q N values increased in ryegrass and tall fescue,and Fm values,Fv/Fm increased and q N values increased in zoysiagrass and early sagebrush.Fm values and Fv/Fm values decreased and q N values decreased.q P values showed an increasing trend for all three grasses except tall fescue,which decreased.(3)Comprehensive evaluation of shade tolerance of four cool-season turfgrassesThe correlation analysis of each index by factor analysis and affiliation function analysis showed that the shade tolerance of the four cool-season turfgrasses was from strong to weak in the order of zoysiagrass > early fescue > tall fescue > ryegrass.The correlation between the shade tolerance coefficients and the shade tolerance D values of the four cool-season turfgrasses was used to filter out the significant correlations with the shade tolerance of the four cool-season turfgrasses,namely: plant height,tillering,belowground biomass,Pn,Cond,respiration rate,Chla,SOD activity,Fm,Fv/Fm.This provides a theoretical basis for garden configuration and selection of turfgrasses,and simplifies the comprehensive evaluation of shade tolerance of turfgrasses.The work..