Genetic Analysis On Grain And Rice Qualities, And Correlation Between Them And Panicle Angle In The RIL Population In Japonica Rice (Oryza Sativa L.)

There are two kinds of panicle type,erect and curve,in japonica rice(Oryza sativa L.) varieties at maturity stage.Erect panicle type variety with small panicle angle has higher yield and worse quality than that of curve panicle type variety with large panicle angle(Lü) W-Y,et al,1997;Yang J,et al,1999).However,it is unknown that the relationship between panicle angle and yield,between panicle angle and rice quality,observed in reality was the result of unconscious selction or inherent.Yield traits included agronomic traits,panicle traits and grain traits.Quality traits included milling quality,appearance quality,cooking and eating quality,and nutritional quality.It is unknown that the relationship between these characters and panicle angle was consistent.In this paper,we analysed the correlationship between panicle angle and grain traits,between panicle angle and quality traits by using 349 recombinant inbred lines(unselected population) derived from the two panicle types of japonica rice(Oryza sativa L.).And genetic segregation analysed of rice quality and grain trait was also carried out using the mixed major gene plus polygene inheritance model. Main results were summarized as follows.1.The linear correlation among panicle angle and 7 grain traits and 12 rice qualities were studied by using the RIL population in Japonica rice in 2005.We found that no significant linear correlation existed between panicle angle and grain thick,grain volume, grain weight by volumn in the 7 grain traits,and between panicle angle and brown rice rate,head rice rate,chalky rice percentage,chalkyness area,gelatinization temperature,gel consistency and apparent amylose content in the 12 rice quality traits.Significant positive or high significant positive correlation was observed between panicle angle and grain width, length-width ratio of grain,milled rice rate,length-width ratio of milled rice.However,the determination coefficients were 0.023,0.029,0.0154 and 0.058 respectively.The correlation had little practicle meaning in biology.High significant positive correlation between panicle angle and 1000-grain weight,grain length,milled rice length was observed. The determination coefficients were 0.15,0.15 and 0.22,respectively,indicating that this significant linear correlationship had meaningful in biology(Table 2-2).Therefore,in unselected population,panicle angle had influence on 1000-grain weight,grain length, milled rice length,while had little effect on other grain and quality traits.To sum up, panicle angle showed certain positive correlationship with 1000-grain weight,while had no correlationship with qualities inherently.It is possible to breed new cultivar with high yield and high quality by genetic improvement.2.Phenotypic distributions were investigated for 1000-grain weight,grain length, grain width,grain thick,length-width ratio of grain,grain volume and grain weight by volume in P₁,P₂ and RILs derived from Bing 8979(erect panicle)×C Bao(curve panicle) in 2005 and 2006.Genetic segregation analyses for the seven traits were conducted by using mixed major gene plus polygene inheritance models and joint analysis method of P₁,P₂ and RILs.Same results were obtained in 2005 and 2006.The results were as followsâ‘ 1000-grain weight was controlled by two linked major genes plus polygenes.The two major genes expressed dominance-epistatic effects(Table 3-4).Grain length and grain weight by volume were controlled by two linked major genes plus polygenes The two major genes expressed additive×additive-epistatic effects(Table 3-9,Table 3-34).Grain width and length-width ratio of grain were controlled by two major genes plus polygenes.The two major genes expressed complementary effect and additive×additive-epistatic effects(Table 3-14,Table 3-24).Grain thick was controlled by two linked major genes plus polygenes.The two major genes expressed recessiveness-epistatic effects(Table 3-19).Grain volume was controlled by two linked major genes plus polygenes.The two major genes expressed complementary effect and additive×additive-epistatic effects(Table 3-34).â‘¡1000-grain weight and grain length were mainly governed by major genes(Table 3-6,Table 3-11).Grain width,grain thick,length-width ratio of grain,grain volume and grain weight by volume were mainly governed by polygenes(Table 3-16,Table 3-21,Table 3-26,Table 3-31,Table 3-36).3.Phenotypic distributions were investigated for brown rice rate,total milling rate, head rice rate,milled rice length,milled rice width,length-width ratio of milled rice,chalky rice percentage,chalkyness area,chalkiness,gelatinization temperature,gel consistency and apparent amylose content in P₁,P₂ and RILs derived from Bing 8979(erect panicle)×C Bao(curve panicle) in 2005.Genetic segregation analyses for the twelve traits were conducted by using mixed major gene plus polygene inheritance models and joint analysis method of P₁,P₂ and RILs.Research results were as followsâ‘ Brown rice rate,milled rice rate and apparent amylose content were controlled by two linked major genes plus polygenes.The two major genes expressed additive effect and additive×additive-epistatic effects(Table 4-3,Table 4-8,Table 4-58).Head rice rate,milled rice width,length-width ratio of milled rice,chalkyness area and gel consistency were controlled by two linked additive major genes plus polygenes.The two major genes expressed additive×additive -epistatic effects(Table 4-13,Table 4-23,Table 4-28,Table 4-38,Table 4-53).Milled rice length,chalky rice percentage,chalkiness and gelatinization temperature were controlled by three additive major genes plus polygenes.The three major genes expressed additive×additive×additive -epistatic effects(Table 4-18,Table 4-33,Table 4-43,Table 4-48).â‘¡Brown rice rate,milled rice rate,head rice rate,grain length,grain width, chalky rice percentage,chalkyness area,chalkiness and gelatinization temperature traits were mainly governed by major genes(Table 4-5,Table 4-10,Table 4-15,Table 4-20, Table 4-25,Table 4-35,Table 4-40,Table 4-45,Table 4-50).Length-width ratio of milled rice,gel consistency and apparent amylose content traits were mainly governed by polygenes(Table 4-30,Table 4-55,Table 4-60).