GA_3 Induced Overgrowth and Its Effects on Morphology in xPopulus alba glandulosa

摘要

GA has been known to have many functions on plant growth and development. These include dormancy break, flower induction, and shoot elongation. In the present study, we examined the effects of GA_3 on stem growth of poplar (xPopulus alba glandulosa)in a nursey. GA_3 at the concentration of 0.2 to 20mg/ml stimulated shoot elongation on the tissue culture derived seedlings as well as the plants originated from root suckers. Although GA_3 stimulated the elongation of shoots, it did not increase the number of nodes on the shoots suggesting that the majority of the shoot growth was due to the elongation, not to new cell division. While GA_3 doubled the growth of both cells in the intemode and thereby the internode itself. In some cases, it also causedthe reduction in chlorophyll contents and both fresh and dry weight of the stems. Abnormal leaf shape was another notable characteristic of GA_3 treated plants. It even appeared in the plants treated with the lowest concentration (0.2mg) of GA_3. If we use leaf abnormalty as the indicator of exogenous GA_3 activity on plants, we might be able to draw the following conclusions: 1) the GA_3 effects last at least till the 8 or 9th new leaf develops on the plants, and 2) GA_3 did not seem to move downward from the apical bud where exogenous GA_3 was treated.