Effects Of NO₃～- On The Characters Of Physiological And Biochemical Of Sweet Cherry Rootstocks Under Waterlogging

Sweet cherry(Prunus avium) is the faster growth cultivated species, which can bring much benefit to the fruit grower. It is shallow rooted plant so it is sensitive to waterlogging stress. The sweet cherry plant is becoming depauperation because of waterlogging, and even died.This brings tremendous loss to the cherry industry. Exogenous nitrate exerted protective action and energy metabolism of plants under waterlogging.On the basis of present study, effect of NO₃^- on the respiratoion and its key enzyme activity , antioxidant enzyme and reactive oxygen species,the Chlorophyâ…¡Fluorescence in roots of the meizhao/colt sweet cheery under waterlogging were studied.(1)The respiration of brown roots decline moderately when compare with that of growing roots. Exogenously NO₃^- alleviated the decrease of respiratory rate and that respiratory rate under waterlogging in the root tissues of sweet cherry can be enhanced with its concentration increased in a certain limit.(2)After waterlogging for 2-3 days, the addition of NO₃^- promote the increase of respiratory rate of Embden-Meyer-hot-Parnas pathway(EMP),Pentose Phosphate pathway(PPP) and Tricarboxylic acid cycle(TCA), as well as enhancement of enzyme activity of pyrophosphate-dependent phosphofructokinase(PFK),glucose– 6 - phosphate dehydrogenase ( G- 6– PDH ) and malate dehydrogenase (MDH). The resistance to waterlogging conditions of 30 mmol/L KNO3 is significantly higher than others.(3)The results showed that under waterlogging , antioxidant enzyme and reactive oxygen species(ROS) in brown roots of sweet cherry increased significantly in the early period of treatment and then decreased in the later period.(4)NO₃^- treatments enhanced the activities of antioxidant enzyme including superoxide dismutase(SOD),peroxidase(POD) and catlase (CAT) that were higher than CK, while the concentrations of O₂·|—,H₂O₂ and MDA that were lower than CK decreased under waterlogging.(5)With the increase of waterlogging, Fv/Fm,Fv/Fo and qP had the trend of decrease–increase-decrease. Exogenously applied NO₃^- alleviated the decrease of Fv/Fm,Fv/Fo and qP,qN on The treatment of NO₃^- were higher than CK.(6) The light energy conversion efficiency, and potential activity of photosynthetic reaction center and the non-photochemical dissipation of excess light enemy, which resisted the damage on photosynthetic apparatus of environmental stress, were improved.