| To reveal the dwarfing mechanism for the Chinese fir, the relationship between low growth potential of the dwarf and anatomical characteristics, photosynthetic properties, chlorophyll florescence parameters, carbon metabolism, enzyme activity, enzyme activity, phytohormones, proteome was studied. The results indicated:(1) Dynamic growth trend of new shoot can reflect the growth potential of two type of Chinese fir, therefore, the characteristics of the dwarf can be evaluated by the index.(2) In the aspect of anatomy of branch and leaf, the average value of bark percentage of the dwarf and control are 76.50% and 37.70% respectively, which shows significant difference between two types; furthermore, the average of mean area of tracheid of the dwarf and control are 241.9016μm2 and 308.8946μm2 respectively, and the significant difference reflects that the diameter of tracheid of the dwarf is smaller, which restricts its water absorption and transportation, and inhibits the nutritional growth of the plant; but for the density of tracheid, the average value of the dwarf and control are 3375/mm2 and 2456/mm2, the dwarf is significantly higher than the control, which may be due to the high ratio of tracheid in the xylem of coniferous plant; in the aspect of the quantity of leaf unit length, the dwarf is significantly more than the control, it may be due to the shorten branch of the dwarf; however, for the proportion of palisade tissue and spongy tissue, there is no significant difference between two types. Consequently, the bark percentage and quantity of leaf unit length can be used for evaluation of characteristics of the dwarf.(3) In the aspect of photosynthetic properties, the light compensation point and light saturation point of the dwarf are 18.44μmol·m-2·s-1 and 500μmol·m-2·s-1 respectively, and the corresponding value of the control are 7.32μmol·m-2·s-1 and 1500μmol·m-2·s-1 respectively, which indicates that the dwarf had less ability on using light than the control. In the aspect of photosynthetic parameters, the net photosynthetic rate (Pn), stomatal conductance (Cond) and transpiration rate (Trmmol) of the dwarf are generally lower than the control, however, the inter-cellular CO2 rate do not have obviously difference between them. Therefore, lower net photosynthetic rate of the dwarf may be due to non-stomata factor. In the aspect of chlorophyll florescence parameters, the parameters such as Fo, Fm, Fv/Fm and Fv/Fo of the dwarf are generally lower than the control. In conclusion, the photosynthetic capacity deficiencies of the dwarf may be one of the important physiological and ecological reasons for its lower growth potential.(4) On the situation of transportation, storage and usage of the photosynthetic products, the starch of the dwarf is hard to transformation, which can not supply the plant with glucose on time. Consequently, the abnormality of carbon metabolism may contribute to the low growth potential of the dwarf.(5) On the study of enzyme activity, it is found that the POD,IOD activity of the dwarf are significantly higher than the control. Therefore, the high enzyme activity of the dwarf may be one of the reason why it has a low growth potential.(6) On the study of phytohormones, it is found that the difference of IAA,ZR content between the dwarf and the control is small, but it is because of the high enzyme activity that the low growth potential of the dwarf may be due to disruption of IAA transportation. It is also found that the GA content of the dwarf is significantly lower than the control, which indicates that the low growth potential of the dwarf may be regulated by the GA. Furthermore, the abnomal ABA lever of the dwarf may be also the reason why it has a low growth potential.(7) On the study of proteome, it is found that the 29 proteins expression of the dwarf have changed significantly, of which 14 proteins increase by 2.2 times, 15 proteins fall more than 3.0 times. The abnormal protein expression of the dwarf these may be closely related to the characteristics of the dwarf. |
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