A Comparative Study On Root Bleeding Characteristics Of Maize Hybrids And Their Parents

In this paper,maize hybrids Xianyu 335,Liangyu 99,Tiannong 9 and the corresponding parent were used as experimental materials,it was respectively sampled and measured for bleeding sap,aboveground biomass and photosynthetic index in the growth stages of maize to analyze the diurnal variation of root bleeding intensity,daytime and nighttime change of bleeding intensity and components,the change of aboveground biomass and leaf photosynthetic index,relationship between root bleeding intensity and aboveground biomass,photosynthetic index.The results were as follows:1.The diurnal variation of bleedingintensity varies with the growth period.It is mostly divided into three stages,the first stage in jointing period and big trumpet period was the "U" type change trend,the second stage in silking period and filling period was change of more stable,slightly fluctuating,and the third stage in the mature period was gradually declining trend.The maximum bleeding intensity was at the morning 5: 00-9: 00,and bleeding intensity in the morning was higher than the afternoon,but this in the afternoon was more stable.The bleeding intensity could reflect the heterosis in the growth period,but it was more obvious in the later growth period.2.There was a strong correlation between the intensity of daytime and nighttime bleeding,but the average value of daytime bleeding intensity was higher than that of nighttime bleeding intensity.The content of soluble sugar,soluble protein,free amino acid and nitrate nitrogen in the daytime bleeding sap were higher than those in the nighttime bleeding sap,while the content of ammonium nitrogen was on the contrary.Soluble sugar,soluble protein,free amino acid content and transport speed in the silking period and filling period were higher measured value,given the accumulation of nutrients for the grain.3.With the growth period going on,the dry weight of stem,leaf and leaf sheath firstly increased then decreased,while the panicle weight,grain weight and dry weight per plant increased gradually.The biomass and dry matter accumulation rate of the hybrids were higher than those of the parents,and the senescence rate of the vegetative organs was the opposite.The net photosynthetic rate increased firstly and then decreased with the growth period going,and the heterosis was not obvious at the early growth stage,and had conspicuous heterosis at the mature stage.4.The correlation analysis showed that daytime bleeding intensity was significantly correlated with the content of soluble protein and ammonium nitrogen,and nighttime bleeding intensity was significantly correlated with soluble sugar content and ammonium nitrogen content.The intensity of daytime and nighttime bleeding intensity of the parents was closely related to the biomass of each aboveground organ during R1,R2 and R3,while the hybrids were closely related to the period of R1.The daytime bleeding intensity and net photosynthetic rate were significantly positively correlated at R3 for hybrids.A comprehensive analysis found thatdaytime and night bleeding intensity and bleeding composition are mutually coordinated and complementarychanges can be deduced from the changes of the daytime and nighttime of the maize bleeding.The content of soluble sugar,soluble protein and ammonium nitrogen can be used to characterize the specific index of maize root bleeding intensity.There was a significant positive correlation between the bleeding intensity of the parent and the biomass of the organs in the aboveground with R1?R2?R3,while the hybrids were significantly positively correlated with R1.There were heterosis from the root bleedingintensityandcomponentsto the aboveground biomass of maize and the photosynthetic index of the leaf,and the performance was more obvious in the later stage of growth.