Interspecific Cross Compatibility of Rhododendron in Changbai Mountain

In order to explore the interspecific cross compatibility of Rhododendron and the feasibility of interspecific cross in germplasrn innovation, reciprocal crosses among five species of Rhododendron in Changbai Mountain were made, In addition, the hybrid embryos were cultured in vitro. The results showed that the species of Rhododendron in Changbai Mountain had significant differences in reciprocal cross compatibility. When Rh. chrysanthum Pall. was used as female parent, it showed high cross compatibilities with Rh. mucronulatum Turcz. （92.55%）, Rh. mucronulamm Turcz. f, album Nakai （94.14%） and Yabuli Rhododendron （92.42%）, and no signifi- cant differences were found in fruit setting rate by serf-poUination. The germination rates of hybrid embryos were 13.60%, 11.59% and 4.12%, respectively. The hybrid seedlings had weak growth vigor and albino status and were trended to be aborted. After 2-3 generations of subculture, the growth vigor of hybrid seedlings were re- covered gradually, and their differentiation rate was also significantly higher than that of Rh. chrysanthum Pall. seedlings. But the hybrid seedlings were still yellowish green. In reciprocal crosses, the fruit setting rates were significantly reduced. The combination with the highest fruit setting rate （36.51%） was Yabuli Rhododendron x Rh chrysanthum Pall The fruit setting rates of reciprocal crosses between Rh chrysan- thum Pall and Rh. mucronulatum Turcz. and Rh.： chrysanthum Pall. and Rh. schlip- penbachii Maxim were 6.52% and 0, respectively. However, the hybrid embryo＇s germination rate （39,81%） of Yabuli Rhododendron x Rh. chrysanthum Pall. was significantly higher than that of their original cross. Moreover, the hybrid seedlings grew strongly and could be directly transplanted without subculture.

Interspecific Crossing between Yam Species (Dioscorea rotundata and Dioscorea bulbifera) through in Vitro Ovule Culture

In the present study, in vitro ovule culture technique was used to obtain interspecific cross combination of Dioscorea rotundata ufenyi and Dioscorea bulbifera wild. Ten days after pollination, ovules were excised and cultured onto 1/2 strength Murashige and Skoog (MS) medium (Basal salt mixture + Vitamins) supplemented with 6% sucrose, 0.7% agar and plant growth hormones such as GA3, BAP, Picrolam and TDZ. Cultured ovules were transferred on 1/2 MS medium with 3% sucrose and 0.7% agar after three weeks. 40 days after pollination, germination was observed from 7 months cultured ovule between D. rotundata ufenyi x D. bulbifera wild. Hybridity of the regenerated plant was checked by flow cytometric method. A close relation was observed between the fluorescence intensity of the obtained progeny with one of the parents’ fluorescence. The observed progeny can be closely correlated with an apomictic tissue from an ovule parent of D. rotundata ufenyi. Plantlets derived from ovule culture were proliferated through in vitro shoot multiplication with hormonal concentration (0.5 mg/l BAP) supplemented with 1/2 strength MS medium. Obtained ovule culture derived in vitro plantlets were successfully hardened, acclimatized and transferred to the field, where they survived and grew normally. In plant breeding, interspecific crossing is very important technique, enabling the time needed to produce homozygous lines to be shortened as compared to the conventional plant breeding techniques.

Growth promotion of interspecific hybrid embryos between Cucumis anguria and Melon(C. melo) by fruit heating

Wild species of the genus Cucumis, such as C. anguria, are resistant to various melon(C. melo) diseases such as Fusarium wilt race 1.2 and are anticipated as genetic resources of melon. However, in the interspecific crosses between C. anguria and melon, the abortion of the embryos was observed in the early growth stage and could not be regenerated even when cultured. Therefore, for embryo rescue, it is necessary to promote embryo growth during abortion occurrence. This study investigated the effects of fruit heating on embryo growth in interspecific hybrids of C. anguria and melon. In the heating device, the minimum night temperature around the fruit was maintained above 21.5 °C. The ovule grain area of C. anguria × MR-1 with fruit heating was significantly enlarged compared to that without fruit-heating. It was also significantly enlarged compared with the ovule grain area of C. anguria self-pollination. Although, in C. anguria × MR-1 without fruit-heating, no embryo was observed until 10 days after pollination(DAP), and pre-embryos were observed at 13 DAP. Conversely, in C. anguria × MR-1 with fruit-heating, pre-embryos were even observed at 10 DAP. These results suggest that the possibility of embryo or ovule culture regeneration has increased due to embryo growth promotion.

Transfer of Superior Traits from Brassica juncea into Brassica napus

Both Brassica juncea（mustard）and B.napus（rapeseed）are allotetraploid species of Brassica.Although these two species have their unique characters,they possess a common A genome and a few homeologous chromosomes between the genomes B and C,which provide the foundation for transfer of superior traits from B.juncea into worldwide cultivated B.napus.The unique characters of B.juncea were summarized,breeding procedure for introgression of superior traits from B.juncea into B.napus by the interspecific crossing proposed,and some recently developed rapeseed germplasm lines with novel traits such as yellow seed and super oil content,restorer of fertility for pol CMS,extreme early maturity,high oleic acid content and short-staure plant briefly introduced in this paper.

Identification of Hybrids between Prunus salicina and Prunus armeniaca by RAPD and SSR

[ Objective] This study aimed to investigate the genetic variation between hybrids and their parents, and to find a rapid identification method. [ Method ] The progenies between Prunus armeniaca （ apricot ） Katy and Prunus salicina （plum） Moriteni were analyzed by means of RAPD and SSR molecular markers. [ Result] We found the differences in the electrophoresis bands between progenies and their parents, indicating that hybrid seedlings obtained in this study were real. [ Conclusion ] The combination of the above methods is effective and fast to identify the hybrids, and can shorten the breeding period.

STUDY ON ECOLOGY OF FRAXINUS MANDSHURICA

The relerence and recent working results about ecology of ash (Fraxinus mandshurica)were reviewed, which including: distribution range, suitable site, phonology, growth, photosynthesis,productivity, natural regeneration effect and mixture effect. Synthesizing above, it was suggest that the ecological characters of ash such as distribution range, limited factors, growth site etc., as well as its biology characters, features in forest, should be considered as an important basis to devclop this species by different regeneration ways such as natural regeneration, artificial regeneratioll and natural regeneration by man-help. And experiment in artificial regeneration showed that the mixture of ash with larch has benefit to being free from or alleviating frost injury and euhancing growth