Compatibility Of Distant Hybridization In Paeonia L. And Identification Of F1 Hybrid Progenies

Peony (Paeonia lactiflora Pall.) is Chinese native flower. For a long time, the breeding has been an important method to improve the ornamental characteristics and resistance quality. However, excellent germplasm resources is the basis for breeding. Therefore, this study introduced a number of new peony cultivars from the United States and tracked observation of adaptability in Beijing. Sexual hybridization were carried out between varieties, interspecies and intersections. Cross combinations with high seed setting rate and distant hybridization offspring were obtained. Meanwhile, the main causes of peony cross incompatibility were discussed through the pollen tube behavior after hybridization fluorescence and provided a scientific basis to improve the efficiency of hybridization breeding. In addition, aiming at low propagation coefficiency, this study attempted to use root cutting and layering asexual propagation ways to improve propagation coefficient of peony and provide practical guidance for industrialized production. The main conclusions are as follows:1. Introduction of new cultivars of peony:This study introduced 25 new peony cultivars including: Lactiflora Group 1, Itoh Group 5 and Hybrid Group 19. Without special management, the introduced cultivars could grew well in Beijing.2. Distant hybridization of Paeonia:67 cross combinations were designed,2073 flowers were pollinated,2627 seeds and 805 seedlings were obtained. Among them, intraspecific cross combinations were 19.2236 seeds and 761 seedlings were obtained. From interspecific cross combinations,418 seeds and 40 seedlings were obtained, whereas 24 seeds and 4 seedlings were obtained from intersectional cross combinations.3. Fluorescence microscopic observation of pollen tube growth:Aiming at the distant hybridization incompatibility of peony. ’Zhu Sha Pan’ was selected as the female parent, ’Dao Da Chen’,’Feng Dan Bai’,’Yao Huang’,’High Noon’ as the male parents to observe pollen tube behavior by fluorescence microscopy. The results showed that pre fertilization barriers was the main reason of hybrid incompatibility.4. Hybrid identification:25 suspected hybrids of 6 combinations were identified by chromosome karyotype and SSR molecular marker technology. The results showed that 21 suspected hybrids were true hybrids.5. Asexual propagation:3 cultivars from different groups were selected for root cutting propagation and layering propagation experiment. Root cutting propagation experiment showed that the optimal combination for rooting was A3B2C1 (IBA 200 mg/L, cultivar’ Sarah Bernhardt’, substrate river sand), the optimal combination for budding was A3B1C2 (IBA 200 mg/L, cultivar ’Coral Sunset’, substrate perlite and turf). Layering propagation experiment showed that the optimal combination for rooting was A3B2C1 (IBA 60 mg/L, cultivar ’Karl Rosenfield’, substrate river sand).