Effects Of Strigolactone On The Growth And Physiology Of Multiflora Ryegrass Under Drought Stress

Multiflora ryegrass(Lolium multiflorum Lam.)has high nutritional value and excellent quality.It is grown on a large scale in the southern part of the country and can be used as a high quality green fodder and commercial turf grass.Drought is one of the main environmental factors limiting plant growth and development.With global warming,the trend of land drought in China has increased significantly,which has a certain impact on plant physiology and growth.Multiflora ryegrass has poor drought tolerance and has difficulty growing under drought conditions.Therefore,how to alleviate the inhibition of multiflora ryegrass growth by drought stress is an urgent problem in the current multiflora ryegrass cultivation process in Fang area.In view of this,this study investigated the effects of exogenous solanum strigolactone on the growth and physiological aspects of multiflora ryegrass under drought stress,using multiflora ryegrass ’common tetraploid’ as the material,in pot and field experiments,based on plant tolerance mechanisms to drought stress.The main findings are summarised as follows:1.The addition of exogenous monocrotaline lactone could alleviate the inhibition of leaf and root growth of multiflora ryegrass by drought stress.There were eight treatment groups:CK(control group),D(drought treatment group),G1(0.01 μmol/L SL addition group),G2(0.1 μmol/L SL addition group),G3(1 μmol/L SL addition group),DG1(0.01μmol/L SL addition group under drought stress),DG2(0.1μmol/L SL addition group under drought stress)and DG2(0.1 μmol/L SL addition group under drought stress).(0.1μmol/L SL group under drought stress),DG3(1μmol/L SL group under drought stress).The test showed that the addition of SL under drought stress significantly(P<0.05)increased the root length of multiflora ryegrass plants.Compared to the drought-fed group,the addition of exogenous SL significantly(P<0.05)increased chlorophyll b and total chlorophyll content,increased chlorophyll a fluorescence OJIP transient curves and reduced Fo,Fj,Fi and Fm values in multiflora ryegrass,and also significantly(P<0.05)increased specific energy fluxes under drought stress.The addition of SL under drought stress increased the soluble sugar content of leaves and roots,and the addition of 0.01 μmol/L SL significantly(P<0.05)increased the soluble protein content of ryegrass leaves.The addition of SL significantly(P<0.05)reduced the MDA content in leaves and 0.1 μmol/L SL significantly(P<0.05)reduced the relative conductivity and MDA content in roots of multiflora ryegrass under drought stress.The addition of solanum lactone had different effects on the activities of different antioxidant enzymes in the leaves and roots of multiflora ryegrass under drought stress,resulting in an increase in SOD,POD and CAT activities in the leaves and roots.2.The addition of exogenous strigolactone under natural drought stress in the field was able to reduce the effect of drought stress on the growth of multiflora ryegrass.The experiment was conducted with four treatment groups:CK(control group),D(drought treatment group),G(SL added group)and DG(SL added group under drought stress).The experiment showed that the addition of exogenous SL under natural drought stress in the field could significantly(P<0.05)increase the plant height and leaf width of multiflora ryegrass.The addition of solanum lactone under field drought stress significantly(P<0.05)increased chlorophyll a,chlorophyll b and total chlorophyll content in multiflora ryegrass,as well as chlorophyll a fluorescence OJIP transient curve,Fo,Fj,Fi and Fm values,quantum yield and efficiency,significantly(P<0.05)increased PIABS and PItotal values,and significantly increased stomatal conductance of multiflora ryegrass.Soluble sugars and soluble proteins in leaves and roots of multiflora ryegrass were increased by the addition of SL under drought stress in the field.The addition of monocrotaline lactone also significantly(P<0.05)reduced the relative conductivity and leaf MDA content of multiflora ryegrass.The addition of monocrotaline lactone also increased the antioxidant enzyme activities in the leaves and roots of multiflora ryegrass,which significantly increased the POD content in the leaves and roots,CAT activity in the roots and SOD activity in the leaves,and highly significantly increased CAT activity in the leaves and SOD activity in the roots.