Effects of Root Application of AMF and SL on Chlorophyll Fluorescence and Antioxidant System of Lolium perenne under Saline Alkali Stress

ZOU Quan; XING Weiming; WANG Ruoding; ZHOU Wenjun

doi:10.15933/j.cnki.1004-3268.2025.06.008

Abstract：To investigate the effects of root application of arbuscular mycorrhizal fungi(AMF)and strigolactone(SL)on the growth,chlorophyll fluorescence parameters,ion balance,and antioxidant enzyme system of Lolium perenne under salt alkali stress,five concentrations(0,0.2,0.4,0.8,1.6 μmol/L)of SL were applied to the roots of perennial ryegrass under 150 mmol/L salt alkali stress,inoculated with AMF Rhizophorus intrapradices or not vaccinated(CK),to explore the mechanisms by which both alleviate saline alkali stress in L.perenne.The results showed that root application of SL could promote AMF infection in L.perenne.The highest AMF infection rate was 62.7%at a concentration of 0.4 μmol/L of SL,and the maximum number of vesicles was 22.3.At a root application concentration of 0.4 μmol/L of SL,compared with CK,the total biomass and root shoot ratio of L.perenne treated with AMF increased by 18.7%and 13.2%,respectively,and the chlorophyll a and chlorophyll b contents increased by 21.1%and 13.4%,respectively;The maximum photochemical efficiency(Fv/Fm),potential activity(Fv/Fo),and actual photochemical quantum efficiency(ΦPSⅡ)of PSⅡ were increased by 4.7%,8.7%,and 32.9%,respectively,while the non photochemical quenching coefficient(NPQ)decreased by 19.3%.The synergistic effect of AMF and SL could reduce the accumulation of Na+in the upper and root systems of L.perenne,increase K+content and K+/Na+to improve plant ion balance.Under the treatment of SL concentration of 0.4 μmol/L,compared with CK,the relative expression levels of PAL and P5CS genes in L.perenne inoculated with AMF increased by 43.4%and 36.0%,PAL and P5CS activities increased by 26.8%and 26.7%,while the relative expression level of PPO gene decreased by 22.9%and PPO activity decreased by 15.6%.In addition,inoculation with AMF increased the soluble protein and proline content of L.perenne,while reduced the rate of superoxide anion production and hydrogen peroxide content.In summary,SL can promote the infection and development of AMF.Among them,the inoculation of AMF combined with root application of SL at a concentration of 0.4 μmol/L improves best the growth status of L.perenne,maintains chlorophyll fluorescence and antioxidant system,and significantly enhances salt alkali resistance.