| This test is divided into two parts,the first part: Five representative improved lines had been bred by the base materials of backbone inbred lines from Non-Reid and Dom groups,which through many generations selection to be used as tested lines.Choosing good quality representative inbred lines from Reid,Non – Reid and Dom three heterosis group respectively as a kind of test.Then piecing together 5 x 7,a total of 35 incomplete diallel cross combination.Analysis of the parent inbred lines and hybrid combinations of heterosis,variance and the combining ability.The second part: Split plot design was adopted for 12 varieties from 5 improved lines and 7 parent inbred lines under the three density of 60000,80000 and 100000 plants per hectare,the materials were sampled in the early stage of maize grain-filling.Multiple comparison was carried out on the main characteristics of each internode stem,then multiple stepwise regression analysis,path analysis and partial correlation analysis were carried out between the main characteristics of each internode stem and lodging rate.To study the decisive factors of maize lodging and the improved effect of improved inbred lines on the lodging resistance.The main research results have the following several aspects:1.The heterosis analysis results of Various characters show that: Overweight advantages more than the combination of the two check varieties have a total of 14 in the condition of zhengdan 958 and xianyu 335 two varieties for comparison,among them,the overweight advantages values were greater than 20 strong advantage combination has 2,respectively JND2×PH6WC,JND5×8–F.In the hybrid combinations which were quipped by improved lines and backbone inbred lines from Reid,Non – Reid and Dom three heterosis group respectively,various characters heterosis value showed good heterosis model for Non-Reid/Dom×Reid,the heterosis model can be widely used in future breeding work.2.The results of the combining ability analysis show that: The results of general combining ability analysis showed that,the better inbred lines in the comprehensive characteristic performance are JND2,JND3,JND5,PH6 WC and zheng 58;The results of special combining ability analysis show that,in equipping 35 hybrid combinations,there is six combination of the comprehensive characteristic performance better,is JND2×Zheng 58,JND2×A87,JND3×PH6WC,JND4×PMO,JND4×A87,JND5×Zheng 58.Among them,the genetic basis of JND2×Zheng 58,JND3×PH6WC and JND5×Zheng 58 this three cross combinations is Non-Reid/Dom×Reid,the genetic basis of JND2×A87 and JND4×A87 is Non-Reid/Dom×Dom,the genetic basis of JND4×PMO is Non-Reid/Dom×Non-Reid.3.The analysis of crushing strength of each internode under the different density shows that: Stem crushing strength of each internode generally present a trend of decline with the rising of population density and internode position,and generally internode 3 to 5 decreased in larger amplitude than internode 2 to 3.In the five improved lines,JND1,JND2 and JND5 present better improvement effect in the character of stem crushing strength,among them JND5 is the best.4.The partial correlation analysis about Stem the main characters and lodging rate showed that: Crushing strength,internode length,the coefficient of ear height,dry weight are the primary factors to determine the lodging rate,second,unit internode dry matter quality,long thick ratio,ear position,internode diameter for lodging rate has different degrees of influence.Among them,crushing strength,dry weight,unit internode dry matter quality and internode diameter this four traits for lodging rate has a negative effect,has Limited effect.Internode length,the coefficient of ear height,dry weight and ear position this four traits for lodging rate has a positive effect. |
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