Abstract:

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. In Jiangsu and Liaoning Provinces, 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 were the main factor of heterosis in rice. Thus, it is very important to understand genetic mechanism of both panicle angle and number of spikelets per panicle. This paper reported phenotypic distributions of panicle angle and number of spikelets per panicle in P₁, P₂, F₁ ,B₁, B₂ and F₂ generations from three crosses Zhendao 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 the two 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 both panicle angle and number of spikelets per panicle were controlled by two major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance-epistatic effects (Table 4 and Table 7); additive effects were principal in panicle angle trait (Table 8), while epistasis effects in number of spikelets per panicle (Table 9); both traits were mainly governed by major genes (Table 8 and Table 9). Therefore, new varieties with good quality and high yield can be breed by using methods of pedigree breeding, backcross breeding or marker assisted selection breeding.

Key words: Japonica rice, Panicle angle, Number of spikelets per panicle, Major genes plus polygene model, Genetic segregation analysis