Research Of Breeding Technique Of Lagerstroemia Indica L.

Lagerstroemia indica L.belongs to lythraceae Lagerstroemia and is deciduous shrub or small tree, and has a long history of cultivation in China at the same time in the garden greening has an important role, deeply loved by large number of people. But the study of Lagerstroemia indica L. breeding research in our country is less, in order to enrich the germplasm resources of Lagerstroemia indica L., cultivate strong resistance, polyploid of Lagerstroemia indica L. varieties, this paper used radiation breeding, polyploid breeding and cross breeding method, combined with resistance investigation and ploidy identification,reached the following results:1. Radiation Breeding and Study on Resistance:(1) In this experiment, in addition to L. Indica the 'Jin 4' germination rate remained unchanged, the germination rate of the other 3 strains decreased with the increase of radiation dose. At the same time, under the same dose, the emergence rate of 'Sihai Shengping' was lower than 'Liuyue Feixue' and 'Panhe 2' and in addition to 100 gy, between each treatment were significant difference; in the range of 25 to 100 Gy, the emergence rate of 'Liuyue Feixue' was slightly higher than 'Panhe 2', and in the range of 150 ~ 300 Gy, the emergence rate of the latter was slightly higher than the former.(2) In addition to L. Indica 'Sihai Shengping', the other 3 strains showed the phenomenon of long stamen patalody, and all strains of the control group did not appear this phenomenon,it was showed that the effect of radiation on the phenomenon of long stamen had a certain role in promoting.(3) According to the 3 consecutive years observation of radiated plants, it was found that2 plants of 'Liuyue Feixue' strains showed strong resistance to powdery mildew; the study on the resistance to powdery mildew preliminary got that 'Zikang 1' was immune to powdery mildew,'Zikang 2' was highly resistant to powdery mildew, 'Sihai Shengping' was moderately sensitive to powdery mildew, 'Liuyue Feixue' and 'Red Rocket' were highly sensitive.(4) Through 3 years of investigation on the growth of some radiation plants,it was foundthat the plant height and ground diameter of 2 disease-resistant plants were higher than non disease-resistant plants and the deciduous period of disease-resistant plants were obviously later than non disease-resistant plants.2. Polyploid Breeding:(1) In the test of treating seed with colchicine only immersing 48 h in 0.05% and 0.1%colchicine concentration had a extremely low germination rate, but the morphological variation rate was higher in the transplanting seedling.(2) In the test of treating stem apex growing point with colchicine, combination with the highest rate of morphological variation was immersing 72 h in 0.6% colchicine concentration,morphological variation rate was 30.4%, far higher than the other combinations, and was the optimum treatment combination.(3) By identification of flow cytometry, preliminary got 1 strain of suspected tetraploid Lagerstroemia indica L..3. Cross Breeding:(1)As female parent of L. Indica 'Sihai Shengping', filial generation were not flowering,and as male parent, filial generation were blossom; the florescence of filial generation were the same as the parents; the flower diameter of vast majority filial generation were between parents; the filial generation of L. Indica 'Liuyue Feixue' and the filial generation of 'Zikang 1'both showed the same color with the male parent, not only the filial generation of 'Zikang 2'and the filial generation of 'Panhe 2' both showed the same color with the male parent, but also both appeared purple flowers which the parents did not have.(2)The leaf size of filial generation was not all between parents, only 'Sihai Shengping'and 'Panhe 2' both crosses and reciprocal crosses, the leaf length and leaf width of filial generation were both between parents. The leaf shape of each filial generation was more oval shaped.(3)The plant height and the ground diameter of each filial generation differ greatly, 'Sihai Shengping'×'Zikang 2' showed the best performance, the biggest variation degree of plant height was 'Sihai Shengping'× 'Liuyue Feixue', the biggest variation degree of ground diamete was 'Zikang 1'×'Sihai Shengping.'(4)Through the technique of chromosome squashing,it was found that each filialgeneration suspected appeared tetraploid.(5) By identification of flow cytometry, it was found that each filial generation all appeared tetraploid Lagerstroemia indica L..