Studies On Cross-compatibility In Dendrobium

According to the breeding objective,28ornamental plants of dendrobium were chosen todo the cross-breeding research. Based on previous research of pollen vitality, pollen storagemethod, best pollination time, parents’ ornamental character, biological character and breedinghistory,140hybridized combinations were coordinated through cross-pollination. The studieswere focused on evaluation of cross fruitifulness and the growth of hybridized fruits andembryo. The main results are shown as follows:1. The method of germination in culture medium is considered as effective in detectingpollen vitality of dendrobium. The optimum culture medium was100g·L-1sucrose+100mg·L-1H3BO3+80mg·L-1CaCl2. The pollen vitality of species was generally higher than that ofcultivar. Based on comparation of4different storage methods, it suggests that freezing-wettingin-20℃is optimum for pollen of dendrobium. Pollen still has pollination ability after beingstoraged90days which wouldnot lead to any negative result to fruit–setting percentage.2. The trend of pollen vitality and male receptivity kept consistent during flowering period,The better results have been found at the beginning of flowering and full-bloom stage. Beforeartificial pollination, it is necessary to clear up excess flowers to guarantee nutrition supply.The hybridized fruits would grow better if the number of pollination does not excess2in eachplant.3. Both intrasection and intersection cross-pollinations are able to produce cross fruits..Most of cross combinations are able to produce fruits only through single direction. Byevaluating cross fruitfulness, D.Little Green Apples, D.Mini Snowflake, D.Frosty Dawn andD.Jodi Ann were considered to show better cross fruitfulness when act as cross female parents;D.smilliae, D.lindleyi, D.chrysanthum and D.denneanum were considered to demonstratebetter cross fruitfulness when act as cross male parents. In addition, D.Little Green Apples,D.Silver Wings, D.Frosty Dawn and D.Jodi Ann were considered to show single bias to be female parent. However, D.smilliae, D.chrysotoxum, D.nobile and D.Mini Stripes wereconsidered to show single bias to be male parent. Section Latouria×Section Pedilonum,Section Latouria×Section Callista, Section Latouria×Section Pedilonum, Section Latouria×Section Callista, Section Latouria×Section Intermediate，Section Formosae×SectionCallista，Section Intermediate×Section Dendrobium which can produce hybridized fruitseasily, demonstrate better cross fruitfulness.4. Fruit abscission was frequently occurred after pollination. The two peak stages were20~30days and100~130days after pollination. The fruit growing curve was a single‘S’pattern, while embryo was generally formed at90d after pollination. Incomplete embryodevelopment is considered as the main reason of the unconspicuous second peak of growingstage. The low rate of embroyo and few seeds had the negative effect on the rate of seedlingsemergence.100~120days after pollination was the best period to conduct embryo rescue.Through the recent two years work on hybridization of dendrobium, some hybridsseedlings have been achieved in lab and the cross breeding systems of dendrobium have beenestablished. All of them were the keystone of advanced studies of cross breeding ofdendrobium in the future.