Genetic Analysis On Panicle Angle And Number Of Spikelets Per Panicle By Using RILs And Six Generations Of Three Crosses Derived From Erect×Curve Panicle 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. In practice, erect panicle type variety has higher yield and worse quality than that of curve panicle type variety (Lu W-Y, et al, 1997; Yang J, et al, 1999). In provinces of Jiangsu and Liaoning, cultivated area of erect panicle type variety in japonica rice has an increasing trend. However, with development of rice market, rice quality is paid more and more attention. In order to breed new varieties with good quality and high yield, it is necessary to combine the advantage of the two types above. Researches showed number of spikelets per panicle was the main factor of heterosis in rice (Virmani S S, 1994; Kato H et al, 1994; Yuan L P 1994; Hong D-L et al, 2002, 2004). Thus, it is very important to understand genetic mechanism of both panicle angle and number of spikelets per panicle. In this study , genetic segregation analysis of panicle angle and some agronomic characters were made by using the major gene-polygene mixed inheritance model with segregating generations and recombinant inbred lines (RILs, F₇/2004; F₈/2005) derived from the two panicle types of japonica rice (Oryza sativa L.).1. Two chapter reported phenotypic distributions of panicle angle, number of spikelets per panicle, panicle length, panicles per plant and plant height in P₁, P₂, F₁, B₁, B₂ and F₂ generations from three crosses Zhen Dao 88 (erect panicle)×C Bao (curve panicle), Bing 8979 (erect panicle)×C Bao (curve panicle) and Bing 8979 (erect panicle)×77302-1 (curve panicle). Genetic segregation analysis for these five traits were conducted by using major gene-polygene mixed inheritance models and joint analysis method of P₁, P₂, F₁, B₁, B₂ and F₂ generations. The results showed that: â‘ These five traits were controlled by two major genes with additive-dominance-epistasis effects plus polygenes with additive-dominance-epistasis effects (Table 2-4, Table 2-9, Table 2-14, Table 2-19 and Table 2-24). â‘¡Additive effects were principal in panicle angle, panicles per plant and plant height traits(Table 2-6, Table 2-21and Table 2-26); epistasis effects was principal in number of spikelets per panicle (Table 2-11); additive effects was principal in panicle length of the cross of Zhen Dao 88×C...