Submergence tolerance threshold of maize under flooded conditions
We studied the maize response to flooding stress,and quantitatively determined the expression and submergence tolerance threshold of the maize under flooded conditions in the low-lying areas along Huai River.Test was conducted in the lime concretion black soil of the Original soil column,6 treatments were treated with burying the corresponding root bag,and flooding in six leaf stage and Huge bellbottom period,respectively.Nutrient content and biomass of two root bags of maize stalk were measured each day during the flood,and overall measurement was performed by uniform sampling after the flood.Significant impact of water-logging on maize growth was found.For the two studied periods,biomass dropped substantially with the extension of submergence time,and absorption of the nutrition elements(N,P,K) was severely inhibited.They were more sensitive in Six leaf stage than in Huge bellbottom period.At Six leaf stage,a parabola relationship(R2 = 0.986) could be fitted between biomass and the flooded time.According to the equation,the time for biomass reduction to half of CK,i.e.submergence tolerance threshold,is three days.The result is consistent with the analysis between biomass and nitrogen content or its cumulant.In conclusion,water-logging would influence the growth of maize seriously,with lower biomass and restraint of nutrients absorption.Varied degrees of influence was observed for different periods of submergence.The submergence tolerance threshold for Six leaf stage is approximately three days.