Mycorrhiza improves plant growth and photosynthetic characteristics of tea plants in response to drought stress

Tea plants are sensitive to soil moisture deficit,with the level of soil water being a critical factor affecting their growth and quality.Arbuscular mycorrhizal fungi(AMF)can improve water and nutrient absorption,but it is not clear whether AMF can improve the photosynthetic characteristics of tea plants.A potted study was conducted to determine the effects of Claroideoglomus etunicatum on plant growth,leaf water status,pigment content,gas exchange,and chlorophyll fluorescence parameters in Camellia sinensis cv.Fuding Dabaicha under well-watered(WW)and drought stress(DS)conditions.Root mycorrhizal colonization and soil hyphal length were significantly reduced by the eightweek DS treatment.AMF inoculation displayed a significant increase in shoot and root biomass production.The relative water content,leaf water potential,nitrogen balance index,pigment content,maximum photometric effect(Fv/Fm,QY_max),and steady-state photometric effect Y(II)(QY_Lss)decreased dramatically,while the leaf water saturation deficit and steady-state non-photochemical fluorescence quenching(NPQ_Lss)generally increased under DS conditions.Mycorrhizal treatment induced significantly higher relative water content,leaf water potential,nitrogen balance index,pigment(chlorophyll,flavonoid,and anthocyanin)content,net photosynthesis rate,transpiration rate,stomatal conductance,intercellular CO_(2)concentration,QY_max,and QY_Lss;however,it resulted in a lower leaf water saturation deficit and NPQ_Lss under both WW and DS conditions,as compared with nonmycorrhizal plants.These results imply that AMF promoted tea plant growth and alleviated negative effects of DS by promoting gas exchange,regulating the water status of leaves,and regulating photosynthetic parameters.