ObjectiveImproving the technical system of triploid breeding to generate new triploid germplasm can serve for developing new varieties with fast growing and higher resistance in P. canescens.

MethodBased on the optimization of technical conditions for inducing pollen chromosome doubling, effects of colchicine on induced 2n pollen of surface structure and triploid production by crossing induced 2n pollen were conducted by taking P. canescens, P. hopeiensis and P. alba × P. glandulosa as experimental materials.

ResultThe results showed that meiotic stages, injection times and the interaction between meiotic stage and injection time had highly significant effects on frequency of colchicine-induced 2n pollen. The optimum treatment combination to induce pollen chromosome doubling was to inject 11 times with 0.5% colchicine solution when pollen mother cells were at pachytene. The highest mean frequency of colchicine-induced 2n pollen was (30.27 ± 8.69)%. Compared with natural 2n pollen, some narrow furrows on the surface of the colchicine-indued 2n pollen were observed, suggesting that colchicine did, to some extent, affect the formation of cell wall of induced 2n pollen. 4 955 hybrid offsprings were obtained by crossing induced 2n pollen with female gametes of P. hopeiensis and P. alba × P. glandulosa, and five real triploids were detected by flow cytometric analysis and somatic chromosome counting. Among the five triploids, two triploids were derived from the cross combination between P. hopeiensis and P. canescens, and three triploids were derived from the cross combination between P. alba × P. glandulosa and P. canescens.

ConclusionColchicine could not only induce pollen chromosome doubling to produce 2n pollen but also affect the formation of cell wall of colchicine-induced 2n pollen and resulted in narrow furrows on ectexine structure in P. canescens. Hybrid polyploid offsprings were successfully obtained by crossing colchicine-induced 2n pollen.