Inducing 2n pollen to obtain polyploids in tulip

Abstract

Polyploids display desirable traits such as high yield, big flower, vigorous growth and strong resistance. Sexual polyploidization using 2n pollen induced by nitrous oxide (N2O) was an effective method to obtain polyploid tulips. In this study, two diploid tulip cultivars ‘Synaeda Amor’ and ‘Carnaval de Rio’ were used as materials to obtain 2n pollen and polyploids. Their bulbs undergoing meiosis were treated with N2O at six atmospheres for 24 h. The 2n pollen was identified based on the change of pollen diameter of parents and the ploidy of progenies. The results showed 2n pollen was successfully induced from these two diploid tulip cultivars by treatment with N2O. However, it was significantly different in induction efficiency of 2n pollen between them. The 2n pollen productivity of ‘Synaeda Amor’ was 16.0%, while that of ‘Carnaval de Rio’ was 26.7%. The maximum pollen grains diameter of ‘Synaeda Amor’ increased from 66.72 to 88.70 µm and ‘Carnaval de Rio’ from 65.24 to 97.66 µm, diploid to polyplod, respectively. Pollen mixtures containing giant pollen grains from ‘Synaeda Amor’ and ‘Carnaval de Rio’ were crossed with diploid cultivars ‘Salmon Dynasty’ and ‘Cheers’. Triploids were detected in the progenies of the four cross combinations, with the polyploidy ratio ranging from 4 to 18%. Whereas polyploids were not found in the progenies from control crosses without treatment. This research revealed that 2n pollen can be produced using N2O treatment and can be applied to induce polyploidy in tulip.