Genetic Segregation Analysis Of Panicle Angle And Spikelets Per Panicle In Japonica Rice (Oryza Sativa L.)

There exists two panicle types at mature stage in japonica rice .One is erect panicle . the other is curved panicle . Erect panicle variety is characterized by small panicle angle . high yield and inferior quality. Curved panicle variety has large panicle angle, low yield and superior quality . To improve the quality of erect panicle variety or to increase the yield of curved panicle variety, it is necessary to understand the genetic basis of the panicle angle and related yield traits . In this study , genetic segregation analysis of panicle angle and spikelets per panicle was made by using the major gene-polygene mixed inheritance model with segregating generations and recombinant inbred lines (RILs, F6) derived from the two panicle types of japonica rice (Oryza saliva L.).Heterosis of FIS made by the two panicle type varieties and correlations between traits in RIL population were also analysed.1.Using P1 , P2 , F1 and F2 in the cross Bing-8979 (erect panicle) and C-Bao (curved panicle ) as analyzing populations, it was found that both panicle angle and spikelets per panicle were controlled by two major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance-epistatic effects . Erect panicle was partially dominant to curved panicle . More spikelets per panicle was partially dominant to fewer ones . The heritabilities of major gene and polygene for panicle angle were 65.35% and 28.78%. respectively ; those for spikelets per panicle were 39.44% and 47.99%, respectively . For both traits , additive effects were principal.2.Inheritances of panicle angle and spikelets per panicle were further studied by using five populations (P1 . P2 , F1 , F2and F2;3 ) derived from the same mentioned above .The results showed that panicle angle and spikelets per panicle were also controlled by two major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance-epistatic effects. Panicle angle was mainly inherited by major gene and additive effect was principal. Spikelets per panicle was largely controlled by polygene anddominant effect was major.3.Based on the RILs population analysis , panicle angle were controlled by two major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance-epistatic effects . Spikelets per panicle and filled spikelets per panicle were controlled by two linked major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance-epistatic effects. Plant height, panicle length and spikelets per cm panicle were controlled by two linked major genes with additive effect plus polygenes. Panicle angle and panicle length were mainly inherited by major gene and the other traits were largely controlled by polygene.4.Heterosis of 10 traits of F1s derived from different panicle type in japonica rice was studied in the 7 crosses derived from varieties with erect panicle Bing-8979 and Zhen-Dao 88 , curved panicle C-Bao and 77302-1. The results showed that FjS yield had a 20.13% average heterosis . Average heterosis of the crosses was sorted spikelets per panicle>filled spikelets per panicle > spikelets per cm panicle> grain yield per plant > panicle numbers >plant height > panicle length >1000-grain weight. Among the traits investigated, panicle number, spikelets per panicle, filled spikelets per panicle and spikelets per cm panicle showed over-parent heterosis: panicle angle and 1000-grain weight showed middle-parent heterosis. Among the combinatins derive from different panicle type , the yield heterosis was the highest in the cross between varieties with erect panicle. The yield heterosis was the second in the cross between varieties with erect panicle and varieties with curved panicle, and the yield heterosis was the lowest in the cross between varieties with curved panicle.5.Panicle angle, plant height, heading date, yield and yield components of a set of 58 selected from "Bing-8979/C-Bao" recombinant inbred lines (RILs) by panicle angle and spikelets per panicle were investigated. The resu...