Growth Characteristics And Dearfing Predetermination Of Stocks And Grafted Plants Of Cornus Wilsoniana

Cornus wilsoniana, a member of Cornaceae, is deciduous tree, endemic to China with ecological and economic importance. Its fruit oil enriching with oleic and linoleic acid, has been edible oil for centuries. Now it became an important bio-diesel feedstock in China. Some bio-energy plantations planted with seedlings from seeds, close to natural plantation was established. However, for its tall plant and long time vegetative growth period, extending the tree as bio-diesel feedstock slowly. To establish dwarfed plantation is inevitable for bio-diesel industry development. So that to screen dwarf stocks and produce dwarf grafted plants is needed.In this paper, Morphological and anatomical structure of stock seedlings and young grafted plants fromlO clones of Cornus wilsoniana were studied by means of paraffin section. Endogenous phytohormone (IAA, ABA,GA3, ZR) content, and enzyme (IOD, POD) activity of leaves from both stock seedlings and young grafted plants of the 10 clones were measured. Correlation analysis on all the tested parameters were calculated, so as to identify indicators for pre-screening dwarf stocks and predicting grafted plant dwarfing shape. The results showed as followings:1. There were great difference among rootstocks and grafted plants of different clones in growth characteristics. Grafted growth trend was close to its rootstock's Growth trend.The height of 2-year old seedlings and grafted plants positively related with the annual increment of height, to some extend, annual increment of height determined the growth trend or dwarfing extent. Then in terms of the annual height increment as predetermination, clone 1 and clone 34 would be the dwarf stocks.2. The anatomical structure of rootstock roots of dogwood affected the growth of grafted plant, particularly, the ratio of average xylem area to whole transverse section area of root, density of trachea were negative correlation with the growth trend of rootstocks and their grafted plants, those would be prediction indexes. And in terms of the indexes, clone 34 was the shortest rootstock, and then clone 1 was the second short rootstock.3. There were no significant correlation between anatomical structure of rootstocks'stem and growth trend of dogwood rootstocks and their grafted plants. That was, stem from rootstock had little impact on the growth of grafted shoot Also, Anatomical structure of grafted shoot has no correlation with its shoot growth.4.There was no significant correlation between the anatomical structure of rootstock leaf and the growth trend of 1-year old and 2 year old rootstocks. However, spongy tissue thickness was positive correlation with growth trend of 3-year old rootstocks, palisade tissue thickness to total thickness of leaf and the ratio of palisade tissue thickness to spongy tissue thickness were both negative correlation with growth trend of 3-year old rootstocks. For the 2-year old grafted plants, annual increment of height was a little negative correlation with epidermis thickness, palisade tissue thickness, palisade tissue thickness to total thickness of leaf and the ratio of palisade tissue thickness to spongy tissue, which would be one of the supplementary indexes.5. The activity of IOD,POD enzyme in rootstocks leaves had significantly negative correlation with growth trends of rootstocks. Can be considered as indexes for choosing dwarf rootstocks. However the activity of POD in grafted shoots leaf has little negative correlation with growth trends of grafted shoots.6. The level of IAA, GA3, ABA, ZR content in leaves from rootstocks and grafted shoots had little correlation with growth trend of rootstocks and grafted shoots. However, both IAA/ABA and IAA+GA3+ZR/ABA had positive correlation with the growth trend of rootstocks and grafted shoots, and which would be the prediction indexes for screening dwarfing plants7. Based on the results of the current paper and the growth situation in the field, it could be concluded that the order of the dwarfing rootstocks was 20>34>12>36>1>19>15>18>22>9; the order of dwarfing grafted plants was 9>1>12>19>36>34>20>22>18>15.