5. Conclusions
It was demonstrated that BC breeding and phenotypic selection
were effective for simultaneous improvement of multiple
complex traits (HY, DT and ST) in rice. The primary target traits
should be selected first in the target environments (TEs) to
achieve the maximum genetic gain. BC breeding for DT in rice
was almost equally effective by strong phenotypic selection in
the TEs and in the winter-season nursery in Hainan. Considerable
genetic gain can be achieved by selection for secondary
target traits among the ILs with the primary traits. Exploiting
genetic diversity in the subspecific gene pools will be of great
importance for future genetic improvement of complex traits in
rice. Finally, the ILs developed in this study provide useful
materials for future genetic/genomic dissection and molecular
breeding for genetic complex traits.