| Lagerstroemia indica, an important ornamental plant, were widely used in Landscaping with some outstanding characteristics of summer blooming, long flowering period, antipollution, strong adaptability. Main breeding subjects of L. indica were focused on strong resistance, gorgeous flowers and ornamentals.The present study were performed to investigate some characteristics in cross-breeding of three different origins of L. indica, including flowering biology, pollen vigor, stigma vitality, pollination methods, cross-compatibility, seed storage and segregation of F1 progenies. The results can provide reference for further cross breeding.The results of flowering biology of the three different origins of L. indica were as follows:Florescence of the three provenance were significantly different. Blossoming period of L. indica Sichuan, L. indica Baokang and L. indica America were respectively 90d,64d and 100d. On the first day of flowering, the petals totally outspread and plenty of transparent mucus and pollens on stigma; In the next day calyx closed up completely with anther darkening and curving stigma covered by yellow pollens. On the third day petals began to wilt, Synchronously, the stigma became brown without mucus. On the forth day, the stigma began to wilt, followed by the petal completely fade on the fifth day.Pollen vigor studied in vitro culture on solid medium were significantly different. Pollen vigor of L. indica America, L. indica Baokang and Sichuan were respectively 87.8%,72.4% and 20%. Longevity of pollen was 6 h-8 h at the room temperature (30-32℃). Stored in 2℃～-38℃,the longevity of pollen last 60 d～90d. The pollen vigor of L. indica in the full blooming stage was significantly higher than that in the early and end of florescence. The longevity of pollen was higher at 9:00-14:30 on the first flowering day and lost activity on the second day after flowering. Stigma receptivity was estimated by benzidine-H2O2 method, results were:The stigmatic receptivity lasted two days and had no activity in the third day which had the higher receptivity after blooming 3.5h～24h. The stigmatic receptivity period of L. indica Baokang was longer than the other two provenances.Pollination methods,setting percentage, germination and seedling rate of hybrid seedling were studied,results as follows:Natural seed setting and cross-breeding rate was higher; L. indica was self-compatibility and different provenance had different self-cross rate. The seed setting under two pollination, without bagging after emasculation and without emasculation after bagging, were lower. Setting percentage, germination and seedling rate were different in different cross combination and different reciprocal cross. The highest and lowest setting percentage and maturing rate were respectively investigated, when L. indica Baokang No.11 and L. indica Sichuan No.1 were used as male and female parents, respectively. Variation in flower color was obvious in F1 generations. Flower colors in most of them were between that of parents. Purple flowers trended to the female parents. Abundant variations in seedling height, root-collar diameter, branches numbers and branches length were observed in seedlings from different crossing combinations. Variance of branches numbers was the biggest.After placed at room temperature in the shade for drying, 1000-seed weight of L. indica sichuan was significantly higher than that of L. indica Baokang, L. indica Amercia's 1000-seed weight was the lightest. Moisture content of L. indica had insignificant difference among the three provenances. Seed storage method and temperature were studied in the present study. Results were as follows:capsules stored in sand had the highest germination rate, which was superior to dry storage and cold storage.2℃was the optimum storage temperature for L. indica's seed.
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