Effects of exogenous ABA application on the photosynthetic characteristics of bermudagrass seedlings exposed to drought stress
[Objective]Examine the impact of exogenous abscisic acid(ABA)on the photosynthetic characteris-tics of bermudagrass(Cynodon dactylon)under drought stress.This study aims to establish a theoretical foundation for mitigating drought damage and promoting stress resistant cultivation of bermudagrass.[Method]Bermudagrass seedlings were exposed to moderate and severe drought stress induced by polyethyleneide-6000(PEG-6000).The determination of photosynthetic pigments,net photosynthetic rate,stomatal conductance and chlorophyll fluores-cence parameters was conducted by foliar spraying 200 and 500 μmol/L ABA under drought stress.[Result]The re-sults indicated a significant decrease in chlorophyll content,net photosynthetic rate,maximum fluorescence(Fm),vari-able fluorescence(Fv)and electron transport rate(ETR)under drought stress,accompanied by an increase in photo-chemical quenching(qP)and non-photochemical quenching(NPQ)(P<0.05).However,the application of exog-enous ABA mitigated the inhibitory effects of drought on photosynthesis,and this mitigation was closely associated with concentration of applied ABA or severity of drought.Under moderate drought stress,500 µmol/L ABA signifi-cantly increased chlorophyll content,maximum photochemical quantum yield(Fv/Fm)and qPof PSII(P<0.05).In the case of severe drought stress,the application of 500 µmol/L ABA resulted in increased chlorophyll content,net photosynthetic rate and water use efficiency,along with a decrease in intercellular CO2 concentration(P<0.05).However there was no significant effect on chlorophyll fluorescence parameters.[Conclusion]Exogenous ABA dem-onstrates the ability to mitigate the damage caused by drought stress in bermudagrass seedlings.This mitigation is achieved by enhancing chlorophyll content,water use efficiency and light energy conversion efficiency,contributing to the adaption of bermudagrass to arid environments.The findings suggest that the application of 500 µmol/L exog-enous ABA yields more favorable effects.
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