The Study On Dwarf Effect Of Apple Dwarf Interstock

In view of site conditions of the orchards in the Northwest, dwarfing rootstock is notsuitable for direct use as rootstock; however, interstock is used in stead of rootstock. Thispaper aims at revealing the dwarfing effects of apple dwarf interstock by investigating theappearance of morphological, growth index, anatomical construction and photosynthesis ofdwarf trees grafted in two common M9and M26interstocks. Also, the research can play thecertain theoretical and practical guiding significance for breeding of dwarfing rootstock,popularization and application, and the research on dwarfing mechanism of other fruit trees.Experiment materials were Malus micromalus seedling as rootstock, M9and M26asinterstocks,“No.2changfu”grafted on M9and M26as cultivar, Fuji/M.micromalus vigoroustrees and Malus micromalus, M9and M26seedlings as control. Materials were measured bythe way of permanent paraffin section and photics microscope photography and chlorophyllfluorescence kinetics, and obtained the following results:1. Morphological and physiological index showed that, compared to Fuji/M.micromalusvigorous trees, the growth of shoots, diameter of shoots, internodes length and the stomadensity of M9and M26dwarfing trees had significantly reduced, dwarf trees grafted on2kinds of dwarf interstocks increased leaf length, leaf thickness and specific leaf weight. Thedwarf apple trees grafted in M9and M26were significantly higher than Fuji/M.micromalusvigorous trees on the content of chlorophyll a, chlorophyll a+b and chlorophyll a/b.2. The research of anatomical structure of leaf and tender shoots showed that, in contrast tothe Fuji/M.micromalus, Palisade tissue/spongy tissue ratio of leaf of scion grafted in M9andM26had significantly increased; tender shoots on the top of annual branches from scion weresignificantly higher than Fuji/M.micromalus vigorous tree on cross sectional diameter andthickness of cortex, while vessel density of tender shoots were significantly lower than Fuji/M.micromalus vigorous tree.3. The research of anatomical structure of trunk of apple tree displayed that wood proportionof scions and interstocks of dwarf trees grafted in M9and M26reduced significantly, but barkproportion increased significantly. At the same time, the wood/bark ratio of scion andinterstock of dwarf trees grafted in M9and M26had significant differences compared torootstocks. 4. The rootstock stem segments of Fuji/M.micromalus vigorous tree were significantly lowerthan scion stem segments on vessel density in the xylem, vessel area and vessel area/xylemarea proportion, while above-mentioned indexes of rootstock stem segments of dwarf treegrafted in M9and M26were greater than the indexes of scion and interstock stem segments.For the same kind of grafted dwarf tree, both M9and M26, interstock stem segments weresignificantly lower on vessel density in the xylem, vessel area and vessel area/xylem areaproportion than scion and rootstock stem segments of the same tree.5. Photosynthetic measurements indicate that the dwarf apple trees grafted in M9and M26were significantly higher than Fuji/M.micromalus vigorous tree on net photosynthetic rate,and the grafted dwarf trees under the influence of M9and M26dwarf interstocks increasedCO2and water use efficiency. Meanwhile, the daily change of Fo and NPQ indicated that, thegrafted dwarf trees under dwarf interstocks had better defense mechanisms to respond tobright and high temperatures, which can make plants better use of light energy to increase netphotosynthetic rates.