Study On Physiological Response Mechanism Of Perennial Ryegrass To Drought Stress

Perennial ryegrass(Lolium perenne L.)is a plant of the genus Potentilla ryegrass,which is one of the most important cold-season turfgrasses in temperate regions.It prefers warm and humid climate,the rhizomes are well developed,have many tillers,the stems and leaves are lush,with strong regeneration and strong green.It is currently the most important turfgrass in China.However,due to its poor drought tolerance,and the great difference in resistance among varieties,the growth shape in each region is different,and the cultivation blindness is high,which easily lead to failure of lawn construction.Therefore,it is of great significance to study the physiological characteristics of ryegrass under drought stress and establish an effective drought evaluation model for the introduction and breeding of drought-tolerant varieties.In order to study the drought resistance of different varieties of perennial ryegrass,this experiment selected four perennial ryegrass varieties of ’Larkbird’,’Vidas’,’Pr521’ and’Pr525’,by using PEG-6000 simulates drought stress in greenhouse,determines the growth physiological indicators of perennial ryegrass,and uses this to initially establish a drought evaluation model.The main research results are as follows:1).Effects of drought stress on perennial ryegrass growthUnder drought treatment,the dead leaf rate of four kinds of perennial ryegrass increased continuously,and the average degree,density,color and texture of the lawn decreased rapidly,while the lawn quality of perennial ryegrass decreased continuously.The water content of ryegrass decreased with the increase of stress.After the stress,the aboveground,root growth rate,fresh weight and dry weight growth of four perennial ryegrass were significantly inhibited,and the degree of inhibition was positively correlated with the degree of drought stress.2).Effects of drought stress on physiological indicators of perennial ryegrassUnder drought stress in perennial ryegrass leaf chlorophyll content decreased significantly,but different varieties of lolium perenne chlorophyll content affected by drought stress,the capability of drought resistance of varieties of higher chlorophyll content,weak drought resistance ability of varieties of content is low,after being forced,the chlorophyll content of ’the lark’ affected by drought stress is small,andcontent in the high state.Drought stress significantly increased the content of reactive oxygen species,cellular lipid peroxidation and cell membrane lipid peroxidation in perennial rrye grass,and the content of MDA in leaves increased.In addition,the content of MDA varied in different varieties,and the stability of cell membrane decreased.The activity of antioxidant enzymes in all four perennial ryegrass showed changes.With the increase of stress time,the degree of stress showed a trend of increasing first and then decreasing.3).Drought resistance evaluation system of perennial ryegrassThrough drought stress experiments on perennial ryegrass,8 indicators were selected,including lawn quality,dead leaf rate,growth height,growth rate,fresh weight growth,water content of root system,chlorophyll content and H202 content.Three principal components were obtained.The first principal component mainly included the growth rate of overground part,the increment of fresh weight of overground part,the rate of dead leaves,and the growth height of overground part.The contribution rate was 67.905%.The first principal component formula:Y1=-0.36X1+0.39X2+0.39X3+0.41X4-0.16X5-0.43X6-0.17X7+ 0.4X8According to the analysis of membership function,the drought resistance of four perennial rrye grass varieties in this experiment is as follows: ’widas’ >’ lark ’>’ Pr521’>’ Pr525 ’.