Fig. 1

Architecture of yield traits and heterosis among 418 combinations. a Spikelet number per panicle (SPP) of inbred parents and their hybrids in Changsha and Sanya. b Proportion of environment variance (including environment-additive and interaction of genetic by environment variance) for yield-related traits in panels of inbred parents and hybrids. c Degree of middle-parent heterosis of four types of combinations for yield-related traits in Changsha. d Degree of middle-parent heterosis of four types of combinations for yield-related traits in Sanya. J×Nip, J×9311, I×Nip, and I×9311 represent the four types of combinations for japonica×Nipponbare, japonica×9311, indica×Nipponbare and indica×9311, respectively. PBP, SBP, KGW, PNP, and GWP represent primary branch number per panicle, secondary branch number per panicle, 1000-grain weight, panicle number per plant and grain weight per plant, respectively. The labeled value in a is the p value of two-tailed heteroscedasticity T-test. The asterisk labeled in c means the significant level at 0.05 between Changsha and Sanya, and NS means the difference is not significant