| Tulip,which belongs to the genus Tulipa L.,Liliaceae family,is the most economically important bulbous ornamental plants.There are 17 wild Tulipa species distributed in China,and 12 species are only distributed in Xinjiang Province.They are helpful to obtain new germplasm resources.The breeding of wild tulips bulbs by seeds is an important way to domestication of wild tulip resources.Therefore,we take a study on seed dormancy and germination of Tulipa sinkiangensis and T.iliensis.The research provided the theoretical basis for the breeding of wild tulips by seeds.We try to use colchicine and oryzalin to induce polyploidy tulip.Using morphology and cytology to identify induced plantlets.The main results were as follows:Water permeability of testa was good,which was not reason for seed dormancy.Seeds were tested for germination at constant temperatures of 5°C,10°C and 15°C?darkness?.The results showed that the germination percentages of T.sinkiangensis seeds were 63.3%on the30th day and 60.0%of T.iliensis at 5°C.The germination percentages were 3.3%at 15°C.It was found that the two wild tulip seeds have morphophysiologically dormancy.Seeds were soaked in different concentrations of IBA and 6-BA and then were carried to the refrigerator at 5°C.The addition of 6-BA at 5°C significantly improved final germination percentages of these two Tulipa species.In 50 mg·L-1 6-BA,soaking for 6 h was better than other soaking time.The germination percentages of T.sinkiangensis was 86.7%.T50 was 3.8days less than the control.500 mg·L-1 6-BA for 6 h treatment was the best for T.iliensis,with germination rate of 87.0%.The T50 was 7.9 days less than the control.Fresh seeds were stored at room temperature for 3 months,9 months,12 months,and 18months.The germination test was conducted at 4°C.The results showed that the longer the storage time,the less germination percentage of T.sinkiangensis.Seeds of T.iliensis stored for 9 months and 12 months had higher germination rate,up to 80%within 10 d.In this study,polyploid induction was performed on two Tulipa species.Some of seedlings had morphological variations.The results showed that 143 mutations of T.sinkiangensis and 50 mutations of T.iliensis were obtained.We obtained 26 tetrapliod of T.sinkiangensis and 13 tetrapliod of T.iliensis.It was most effectively induced by immersing seeds in 1.0 mg·L-1 colchicine solution for 24 hours for T.sinkiangensis and in 0.5 g·L-1 for12 hours for T.iliensis.The morphological variation rate was 77.1%and 71.4%,respectively.We obtained 87 mutations of T.sinkiangensis and 46 mutations of T.iliensis by culturing seeds with colchicine.22 tetrapliod of T.sinkiangensis and 15 tetrapliod of T.iliensis.The results showed that culturing seeds for 20 days with 0.5 g·L-1 colchicine was the most effective treatment for T.sinkiangensis and T.iliensis with the highest induction rate of 91.7%and 69.2%,respectively.Adventitious buds from germinated seeds cultured on the medium with orazylin grew weaker and eventually died.Some plants did not form bulbs after treated with colchicine.16 bulbs were formed in T.sinkiangensis tetraploid plants and 10 bulbs were formed in T.iliensis tetraploid plants.According to the cytological study,the chromosome number in the contrast strain is2n=2x=24,but in the mutants is 2n=4x=48.The leaves of tetraploid plants became shorter and thicker,the stomata became larger and the bulbs obtained became bigger. |
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