Analysis of the combining ability and genetic parameters in seed phosphorus use efficiency of different rapeseed carltivars ( Brassica napus L. )

In this study, the heterosis and genetic parameters of phosphorus use efficiency for seed production (PUEs) of rapeseed (Brassica napus L.) were investigated using two-factors split experiment. Twenty two parental cultivars (17 female and 5 male parents) and their 175=85 F1 hybrids were grown in soils applied P2O5 150 kg/ha and without P2O5 application(CK). The results showed significant heterosis in hybrids in PUEs. The PUEs in hybrids increased by 6.41%, 7.64% respectively in comparison with parents under CK and P150 treatment. Positive heterosis of mid-parent values (Hm) in PUEs are significantly higher than negative Hm, and positive super high heterosis are significantly higher than negative super low parents. The general combining ability (GCA) variance in PUEs is relatively small, the specific combining ability (SCA) variance is relatively large, and the PUEs is mainly controlled by dominance and epistasis effects. The GCA of inbred line 9 (ZS-3) and SCA of 620 (SY07Xiang 05499), 1320 (NY-14Xiang 05499) and 1421 (Xiang 05487YY-7) are relatively high under two fertility levels.