Diallelic analysis of genetic effects determining days to flowering in kenaf

The genetic control determining the days to flowering, defined as the number of days from emergence to the beginning of flowering is considered an important characteristic for breeding purpose. We investigated this factor in kenaf (Hibiscus cannabinus L.), as part of an agroindustrial project in northwest Argentina. A diallelic cross approach was considered in this study. Six highly inbred photosensitive cultivars were used in the cross, namely, Endora, Pandora, Tainung 1, Line 42, Line 21, and Line 29. Significant differences among F1 family means as well as among general combining ability (GCA) and specific combining ability (SCA) components were found based on the Griffing genetic-statistical method IV, Model 1. A predominant additive effect was detected for the days to flowering, giving high heritability estimates (H = DGD = 0.96; h2 = 0.69), and suggests the possibility of effective selection for earliness in these cultivars. Early flowering in Line 29 was highly heritable, and therefore, is important for breeding purposes. Line 42, despite being the earliest, did not transmit this characteristic to its progenies, possibly because of epistatic genetic effects. The regression of the covariances of F1 families on the non-recurrent parent (Wr) and the variance of the “n” families (Vr) revealed that some dominance effects also occurred in the form of a partial dominance for early flowering. These results support the evidences revealed by the analysis of means of combinations between early and late flowering lines.