Effects of Mixture Compound of Ethephon and Mapiquat Chloride on Root Exudates of Summer Corn

Ethephon and mapiquat chloride was mixed and then used for investigation of effects on the root exudates of summer corn cv.3315 in 1996.The mixed compound was sprayed at floret differentiation stage,and the root exudates volume,flow rates of nutritional elements(N,P,K,B,Fe,Mn and Zn) and endogenous hormones(ABA,IAA,GA and CTKs) in root exudates were determined during tasselling stage to waxy-mature stage.It was found that the root exudates volume reached the peak around the silking stage,then decreased as the plants grow old and mature.The flow rates of nutritional elements and endogenous hormones appeared the same trends with the changes of root exudates.Compared with the control,the treatment with mixed compound showed a slightly lower root exudate volume,a higher flow rate of nutritional elements before silking stage or kernel formation,and a higher flow rate of endogenous hormones before silking stage,after then both rates of nutritional elements and endogenous hormones were lower than those of control.Above results suggested that the mixed compound of ethephon and mapiquat chloride could affect the root exudates volume,nutritional elements and endogenous hormones.