To provide a theoretical basis for further improvement of Brassica napus yield, additive dominance with additive - by - additive epistatic effects （ ADAA） genetic model and a 6 X 8 partial dial- lel cross design were used to analyze the genetic effects and correlations of five yield related traits of 14 excellent Brassica napus parental lines and their 46 and F2 populations. The results showed that silique density （SD） , siliques per plant （SPP） , seeds per silique （SPS） and thousand - seed weight （TSW） exhibited not only additive and dominant effects, but also significant epistatic effects. The dominant effects of all five yield - related traits were obviously greater than their additive effects and epistatic effects. Yield per plant （YPP） showed significant genetic correlation with SD, SPP and SPS, and the main component of the genetic correlation was the dominance correlation. SPP and SPS both showed a significant negative correlation with TSW. The SD of rapeseed was genetically correlated with all three components of yield to a certain extent, and there were different components of genetic effects positively correlated with the three yield components, indicating that SD is a potential trait to reconcile the conflict between TSW and SPP as well as SPS.
Hui WANGQiong HUJun WANGYunchang LILi FUJia LIUZhongfen WEIWenxiang WANGDesheng MEI
Pod shatter resistance of rapeseed is of great importance for modem farming practice. In order to determine the combining ability of elite inbred lines and the breeding potential of rapeseed hybrids in terms of pod shatter resistance, analysis of a 6×6 incomplete diallel cross was conducted at two locations. Results showed that a significant variation existed among breeding lines and their F1 hybrids for pod shatter resistant index （SRI）, pod length and width. Pod shatter resistance was significantly positively correlated with pod length. The general combining ability （GCA） effects （GCA=l.58） played a more important role than specific combining ability （SCA） effects （SCA=0.20） for pod shatter trait. The elite lines R1, 1019B and 1055B displayed significant positive GCA effects for pod shatter resistance. Four crosses （1019B×R1, 1015B×R1, 6098B×R1, and 8908B×R1） with high mean performance and positive SCA effects were recommended for developing new hybrids for mechanical harvest in the middle reaches of the Yangtze River.
LIU JiaMEI De-shengLI Yun-changCUI Jia-chengWANG HuiPENG Peng-feiFU LiHU Qiong
Oilseed rape （Brassica napus L.） is one of the most important oil crops worldwide and provides about 50 percent of the vegetable oil supply in China （Yin et al., 2009）. The development of rapeseed varieties with higher yield is an effective measure to optimize balance between the supply and demand of edible vegetable oil. In oilseed rape, the number of silique per plant （SP） contributes most to the yield performance （Diepenbrock, 2000）. However, compared with the other two yield-component traits, seeds per silique （SS） and seed weight （SW）, SP is more sensitive to environmental changes （Li et al., 2007; Shi et al., 2009）. Therefore, it is difficult to perform the genetic improvement on SP trait directly in oilseed rape.
