Studies On The Biological Characteristics Of Ornamental Crabapples Cultivars

The morphologic characteristics, physiological characteristics were studied on the 14 ornamental crabapple cultivars in Malus in this experiment. The main results were as follows:1 The studies described the morphologic characteristics of 14 ornamental crabapples introduced from foreign. A taxonomic key was supplied to distinguish the different cultivars about the main morphologic characteristics. All we did is to supply the growth and spread the scientific reference.2 The apomixis and ploidy of 10 ornamental crabapple cultivars and the control in Malus Mill were studied by three treatments: castrated flowers whithout pollination were bagged; castrated flowers with artificial pollination were bagged; flowers without castration and artificial pollination were bagged. The result showed that M.'Indian summer'and M.'Snowdrift'had the different ability of facultative apomixis. The apomictic ability of M.'Strawberry parifit'without pollen was the highest. Rate of fruit-set of M.'Strawberry parifit'castrated without pollination was 95.2%, and rate of seed-set was 97.0%. Then was M.'Snowdrift'and M.'Indian summer'. Furthermore, these cultivars showed high ability of self-pollination except M.domistica'maypole'. The self-pollinated ability of M.'Snowdrift'was the highest that was 90.7%, which was rare in other Malus plants. Taking the relation between polyploidy of the cell and apomixis into condition, the ploidy of 10 cultivars was also identified by using FCM. The data of the FCM indicated that M.'Strawberry parifit'whthout pollen was the only triploid. All of the rest with pollen were diploid, which indicated that the diploid plants also had the ability of apomixis.3 Ornamental crabapple cultivars including M.domistica'Maypole', M.'Strawberry parifit', M.'Radiant', M.'Royalty', M.'Snowdrift'and M.'Pink spire'were studied on the photosynthesis and fluorescence. It was found that one-peak was the main pattern in the daily change of leaves photosynthetic rate (Pn) except of'Radiant'which showed the two-peak pattern. The high peak of photosynthetic rate appeared at 11:00 in all cultivars except'Radiant'at 11: 00 and 15: 00. All showed that high temperature and low humidity caused the photoinhibition. The daily change curve of Chla fluorescence parameters including ratio of variable fluorescence to maximal fluorescence (Fv/Fm) and non- photochemical quenching (QN) is''v'', and the lowest point is at 13:00 in all cultivars. However, the trend of NPQ diurnal change is negative. The diurnal variation extent of Fv/Fm existed difference between different cultivars. The variation of M'.Radiant'is the highest that is 16.59%, and the lowest is...