Exogenous NO3- enhanced sugar contents and sucrose correlated enzymes activity in roots of sweet cherry under waterlogging condition.

Effects of exogenous NO3-on sucrose,glucose,fructose and starch contents as well as sucrose synthase(SS)disassemble activity,sucrose synthase synthesis activity,neutral invertase activity(NI)and acid invertase activity(AI)in roots of sweet cherry(Prunus avium 'Daihong')with P.pseudocerasus var.'Daqingye' as rootstock under waterlogging condition were studied.The results showed that under water-logging condition,sucrose,glucose,fructose and starch in roots of sweet cherry increased significantly in the early period and then decreased in the later period in both treatment and control.Exogenous NO3-enhanced the contents of sucrose,glucose,fructose and starch,which were higher than control,while to the maximum,which were 18.02%,21.97%,25.27% and 11.41% higher than that of control respectively when reached to the maximum.The sucrose synthase disassemble activity in roots of sweet cherry increased to the highest level and then declined gradually in both treatment and control.Meanwhile,the sucrose synthase synthesis,NI and AI activities decreased gradually,but four enzymes activities of treatment were higher than that of control after using exogenous NO3-.We conclude that the addition of NO3-can enhance the tolerance of the roots of sweet cherry to hypoxia through regulation of sugar metabolism.