Abstract:
Three American
Lagerstroemia indica varieties (Red Rocket, Red Fireball and Red Leaf) and two Sichuan native
Lagerstroemia indica varieties (Sichuan Pink Flower and Sichuan White Flower) were used as parents for intraspecific hybridization. Three seed traits, including fruit setting rate, seed setting rate and seed germination rate, were investigated, and the heritability, correlation heritability and correlation coefficient of the three seed traits were determined. The progeny were inoculated by the spore suspension infection method, and the hybrid combinations resistant to powdery mildew were screened according to the disease classification of the progeny. The results showed that: (1) There were significant differences in seed and fruit characters of hybrid progeny, and they were significantly lower than those of open pollinated progeny. (2) The seeds
of 12 hybrid combinations were harvested, and only 8 of them could germinate. Therefore, parental collocation should be fully considered in
Lagerstroemia indica hybrid design. (3) The heritability of fruit and seed traits was all above 0.99, and the correlation heritability of fruit setting rate with seed setting rate and germination rate was all above 0.8. The efficiency of early selection of seed setting rate and germination rate by using fruit setting rate traits was 88.37% and 84.47%, respectively. (4) The powdery mildew resistance test of the offspring of 8 hybrid combinations showed that some hybrid progenies of Sino-American combination was good, while others were very poor. The F1 generation of the hybrid combination "Red Rocket × Sichuan White Flower" showed the best resistance, all the tested progenies were resistant to the disease, and the hybrid combination of "Red Rocket × Sichuan White Flower" showed the second best resistance. However, the F1 generation of "Sichuan Pink Flower × American Red Leaf" had the worst resistance. The hybrid of local varieties represent equilibrium. (5) Initially, 8 immune plants and 25 highly resistant plants were screened out. The hybrid combinations and disease-resistant types of powdery mildew resistance discovered in this study provide the material basis for
Lagerstroemia indica resistance breeding.