Objective Genetics on the phenotype of Lagerstroemia limii was studied to breed improved hybrids with 'Qianceng Feixue'.

Method Populations of hybrids between the tree-type L. limii (FJ) and the shrub-type 'Qianceng Feixue'(QC) were generated for the study. Seven phenotype traits including the height, diameter, and length of 1^st branch of one-year-old plants were measured for correlation analysis among them. Major gene+polygene inheritance models were tested for best fitting in predicting hybrid phenotype.

Result (1) The plant height of the hybrid progenies ranged 1.50–24.5 cm, the trunk diameter 0.30–4.44 mm, the 1^st branch length 0.50–6.20 cm, and the branch number 0–4. These traits were basically in a normal distribution pattern among the hybrids with potential arborescent germplasms. (2) The coefficients of variation on the 7 traits were 31.72%–240.42% with the greatest on the number of branches and the least on the height of the first branch in the QC×FJ population. The coefficients of variation of primary branching point height, opening angle, and lateral branching GSA were larger in the FJ ×QC population than in the QC × FJ population, and the FJ × QC group tended to show higher plant height, thicker ground diameter, and more branches, indicating that the hybrid progeny of L. limii as the mother plant had richer strain variation. (3) The plant height significantly correlated with the trunk diameter, the number with the angle of the branches, and the angle with the GSA of the branches. (4) The best fit model for the plant height, trunk diameter, and branching angle was 2MG-AD, and that for the branch GSA and 1^st branch length 2MG-EA.

Conclusion L. limii (FJ) appeared to be a plausible candidate for breeding hybrids with L. indica (QC) that could inherit the desirable phenotypes of growing vigorously, being free of branches on base of trunk, and showing the main trunk prominently.