Study On The Heredity Of Apparent Photosynthesis And Its Relationship With Yield In Soybean

Four soybean varieties with various photosynthetic efficiency and their 30 progenies from complete dialled cross (F1,F2,BC1,BC2) were employed to study the genetic rule of main photosynthetic characteristics in the experimental field of Soybean Research Institute of Heilongjiang Academy of Agricultural Sciences in 2007. The correlation between the main photosynthetic characteristics and agronomic traits of high photosynthetic efficiency varieties were analzed.We measured the main photosynthetic characteristics and chlorophyll fluorescence inducement dynamics parameters of function leaf in three key growth stages, and examined the main agronomic traits after harvest.We analyzed the combining ability,heritability,heritability variance and genetic correlation using the QGA Station model developed by ZhuJun. The joint scaling test were carried out on the genetic effect model for photosynthetic characteristics of cross P₁×P₃. The results are as following :1 Combining ability analysis of photosynthetic characteristics and chlorophyll fluorescence inducement dynamic parameters in different growth stagesCombining ability analysis for photosynthetic characteristics in three main growth stages indicates that their combining ability variance are at different significante levels .The analysis of combining ability effect for photosynthesis (Pn) and transpiration rate (Tr) show that P₃ and P₄ display well in general combining ability.The specific combining ability display well in combinations P₁×P₃,P₃×P₄,P₂×P₃ for Pn., and combination P₃×P₁,P₁×P₄,P₁×P₂ for Tr, indicating that P₃ and P₄ are suitable crossing parents for high combining ability in photosynthetic characteristics.In R3 stage the contrast dominant index of Pn and parents means show that the value of Pn of F1 are close to parents for the combination pairs P₁×P₂ and P₂×P₁,P₁×P₄ and P₄×P₁,P₁×P₃ and P₃×P₁,P₃×P₄and P₄×P₃ 4 ,but the value of Pn of F1 for P₁×P₂ and P₂×P₁,P₁×P₄ and P₄×P₁ are close to female parent for combination pairs P₁×P₂ and P₂×P₁,P₁×P₄ and P₄×P₁ , meanwhile that of the combination pairs P₁×P₃ and P₃×P₁,P₃×P₄ and P₄×P₃ are close to male parent.The contrst dominant index is slightly bigger for combinations P₂×P₃ and P₃×P₂,P₂×P₄ and P₄×P₂.2 Heritability estimation of photosynthetic characteristics and chlorophyll fluorescence induction parameter in different growth stages.The heritability of each characteristics display distinctively in different growth stages.The general heritability is higher for Pn,stomatal conductance (Cond) , Tr and incipient fluorescence (Fo). The general heritability just is higher in beginning pod stage (R3) for Ci and WUE,indicating they are inflenced much by environment. The broad-sense heritability of max fluorescence (Fm) and max photochemistry efficiency (Fv/Fm) are in the middle.They are not suitable characters to be selected in lower generation.The narrow-sense heritability is low for eight characteristics in three growth stages.The narrow-sense heritability of Pn , Fo and Fv/Fm are 24.98%,17.54% and 10.98%, respectively in R5 stage , so their additive variance in proportion to phenotypet variance is a little higher.3 Genetic variance analysis of photosynthetic characteristics and chlorophyll fluorescence induction parameter in different growth stagesThe genetic variance in proportion to phenotype variance is different for photosynthetic characteristics and chlorophyll fluorescence induction parameters.The addictive and dominant variance in proportion to phenotpe variance is significant at 5% level for Pn,Tr and Fo indicating they are easier to be influenced by addictive and dominant effect and can be selected in early or medium generations.The addictive variance in proportion to phenotype variance is lower and the dominant variance can achieve to 10% significance level for Cond,water usage efficiency (WUE) and Fm,so they are influenced more by epistasis or environmental effect.Genetic variance in proportion to apparent variance is little for Ci and Fv/Fm,so they are inflenced more by environment.It is unreliable to select in early generations.4 Genetic correlation analysis of photosynthetic characteristics,chlorophyll fluorescence induction parameters and agronomic traits in different growth stagesThrough the genetic correlation analysis of main photosynthetic characteristics in three growth stages, it is known that the correlation between Pn and Cond, Tr are present positive and that between Pn and Ci is negative but not significant in R3 and R5 stage.The correlation between Pn and WUE is present positive in R3 and seed stage (R6) ,but the correlation coefficient is very small in R5 stage.The correlation between Pn and Fm,Fv/Fm is significantly positive in R5 stage.Pn and Cond, Tr is close in the addictive and dominant coefficient correlation.The addictive and dominant coefficient correlation between Pn and Cond is 0.975 and 1.000. It is 0.796 and 0.843 between Pn and Tr.The addictive and dominant coefficient correlation between Pn and Fm,Fv/Fm achieved significant level,the coefficient correlation is 0.863 and 0.972, respectively.Correlationship of the phenotypic,genetic and dominant is significant between Pn and per plant weight,per plant seed weight,harvest index is obvious.Genetic correlation between photosynthesis and other agronomic traits is week.The multiple correlation analysis indicate that coefficient correlation of three agronomic traits for Heinong40 is higher than that of Heinong26.5 Genetic effect model test for photosynthetic characteristics in different growth stagesUsing the joint scale method to test the photosynthetic characteristics for combination P1×P₃ in R3 and R5 stsges.The results indicate that Cond, Tr and Ci accord with five-parameter model in R3 stage.They are controlled by midparent,addictive,dominant,double addictive and double dominant effect .There is no suitable model for Pn and WUE in R3 stage.Pn and Cond fit for five-parameters model in R5 stage,but there is no suitable model for Ci, Tr and WUE.So it is distinct for the controllong genetic parameters of photosynthetic characteristics in different growth stages.