Hybridization Breeding Technics Of Several Species Of Melastoma Linn

There are nearly 100 species of Melastoma Linn. (Melastomaceae) in the world. Ornamental value of most Melastoma species is still undeveloped. Cross breeding is an effective way to inherit excellent parental characters. In this study, Melastoma affine, M. candidum and M. sanguineum were applied as materials, whose heteromorphic stamens pollen viability, suitable storage conditions for the pollens were investigated; Moreover M. candidum, and M. sanguineum were used as materials to investigate the cross compatibility of Melastoma L., their offsprings were identified by morphology, in order to provide basic information for the cross breeding of Melastoma L.. The main conclusions as follows:(1) Determination of pollen vitality by stainingI2-K.I could not determinate the pollen vitality effectively. Compared with the method of germination in vitro, the vitality determined by TTC staining was relatively higher. Benzidine staining could determinate the pollen vitality of M. affine effectively, while the pollen vitality of the others two species were on the high side. For M. affine and M. sanguineum, long stamens pollen vitality were higher than the short ones, while M. candidum had no significant difference.(2) The best culture medium for pollen germinationThe best culture medium were confirmed by orthogonal test L9(34). The pollen germination characteristics that came from the same material were basically identical, no matter the long stamens or the short ones. The best culture medium for pollen germination of M. affine, M. sanguineum and M. candidum are 20 g·L-1 sucrose+200 mg·L-1 H3BO3+100 mg·L-1 CaCl2+culture temperature 30℃,20 g·L-1 sucrose+50 mg·L-1 H3BO3+100 mg·L-1 CaCl2+culture temperature 20℃ and 10 g·L-1 sucrose+ 100 mg·L-1 H3BO3+50 mg·L-1 CaCl2+culture temperature 30 ℃, respectively. For M. affine and M. sanguineum, the pollen germination rate of long stamens was higher than that of the short ones, especially the difference was significant in M. affine, while M. candidum was no significant.(3) The storage conditions of pollenThe pollen was dry preserved at room temperature,4℃,-23℃ and-80℃, then the vitality was measured regularly. The results indicated the lower preserved temperature, the higher pollen vitality. Pollen dry preserved at-80 ℃ was the best storage condition, the germination rates are still at a high level after 120 days, The storage of heteromorphic stamens pollen from the same material were basically identical.(4) The compatibility of hybridizationThe growth of pollen tube at different time was observed by fluorescence microscopy. The results shows pollen from heteromorphic stamens germinated and grow into the bottom of stigma after 24h, For M. candidum, the callose appeared in the top of stigma, some of which appeared along pollen tube wall as well. For M. sanguineum, the callose appeared in the upper of stigma.The fruit set, the plumpness of seeds, and seed germination were counted. The results show that cross-compatibility between M. sanguineum with M. candidum was high; There was no significant fertilization failure, suggesting their close relationships. The effect of pollination of M. sanguineum long stamens were better than the short ones, while M. candidum had no significant difference.(5) Preliminary identification of hybridsCompared with self-bred progenies, most of hybrids have higher plant height and Larger leaves. The number of leaf vein was 7 which was as same as M. candidum. There are not significant difference between offspring who has the same father, heteromorphic stamens had no significance effects on the morphology of offspring, the leaf shape of offsprings came from obverse cross were ovate-lanceolate and shoots were covered with short coarse wool, while inverse cross were ellipse-lanceolate and shoots were covered with scale wool.