| Lagerstroemia belongs to the Lythraceae family and is mainly distributed in temperate and tropical regions of the world.There are about 55 species of this genus worldwide,and 16 species are native to my country.Lagerstroemia indica is a famous ornamental plant in summer.Its flowering period can reach 100 d.It is also known as Hundred Days Red because of its gorgeous flower color and long flowering period.Lagerstroemia is widely used in gardens.In this study,two varieties of crape myrtle,‘Fenjing’and‘Cuipan Jinwei’were used as parents to carry out positive and negative crosses.The growth process of pollen tubes after pollination was observed using a fluorescence microscope,and the external development morphology of the positive and negative cross fruits was studied.The internal embryo development process,the hybrid ovules and immature embryos at different embryo development stages were used as explants and cultured in vitro,and the environmental conditions affecting the germination of embryos and ovules were studied.The different ratios of exogenous hormones are important for initiating culture.Produce a suitable medium and hormone combination.The main findings are as follows:（1）Observation results under a fluorescence microscope show that the pollen vigor of the hybrid parents is higher,and the stigma is more pollinable.After 3 hours of pollination,the pollen and the stigma have germinated in a large amount.‘Fen jing’בCui pan jin wei’has germinated in large quantities 1h after pollination,and the pollen tubes all enter the ovule 24h after pollination.（2）The microscopic observation results of paraffin sections showed that the embryos of‘Cui pan jin wei’בFen jing’developed into the zygotic embryo stage at 10 days after hybridization,and developed into globular embryos at 14 to 16 days after hybridization,and at 18 days after hybridization.Heart-shaped embryos develop into torpedo embryo stage 20 days after hybridization,and cotyledon embryo stage after 25 days hybridization;‘Fen jing’בCui pan jin wei’is globular embryo stage at 9～12 days after pollination,14～16 days after hybridization It is the heart-shaped embryo period,18 days is the torpedo embryo period,and 20 days is the cotyledon embryo period.The development process is accompanied by the existence of the endosperm free nucleus.When it develops into the cotyledon embryo,the endosperm free nucleus is completely absorbed.（3）The results of culture of ovules at different developmental stages showed that light and dark control treatments had no significant effect on the germination of ovules,and the germination rate gradually increased with the development of the developmental stages;The suitable primary culture medium for the hybrid combination of‘Fen jing’בCui pan jin wei’is WPM+1.0 mg·L-16-BA+0.2mg·L-1 NAA and MS+0.6 mg·L-1 6-BA+0.2 mg·L-1 NAA,The subculture medium is MS+0.6mg·L-1 6-BA and WPM+0.6 mg·L-1 6-BA,and the rooting medium is 1/2MS+0.6 mg·L-16-BA+1.0 mg·L-1 IBA;The suitable primary medium for‘Fen jing’בCui pan jin wei’is MS+0.6mg·L 6-BA+0.2 mg·L-1 NAA,the secondary medium is MS+0.6 mg·L-1 6-BA,rooting medium1/2MS+0.6 mg·L-1 6-BA+1.0 mg·L-1 IBA and 1/2MS+1.0 mg·L-1 IBA.（4）The results of embryo culture showed that the light and dark control treatments also had no significant effect on the germination of embryos.The suitable primary medium for the hybrid combination of‘Fen jing’בCui pan jin wei’is MS+0.2 mg·L-1 6-BA+0.6 mg·L-1 NAA,the subculture medium is MS+0.6 mg·L-1 6-BA+1.0mg·L-1 NAA and WPM,the rooting medium is1/2MS+0.2 mg·L-1 6-BA+0.6 mg·L-1 IBA;‘Fen jing’בCui pan jin wei’suitable primary medium is MS+0.2 mg·L-1 6-BA+0.6 mg·L-1 NAA,and the secondary medium is MS+0.6 mg·L-1 6-BA and WPM,rooting medium 1/2MS+0.2 mg·L-1 6-BA+0.6 mg·L-1 IBA. |
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