火炬树克隆分株前后端水平侧根直径不对称性分析

Analysis on Asymmetry of Horizontal Lateral Root Diameterin Clonal Ramets of Rhus typhina

以1、2和3年生火炬树克隆分株为研究材料,分别于2003年生长季取样,研究激素的种类和含量、光合产物分配特征以及前后端水平侧根的形态解剖差异.结果证实:9株1年生火炬树克隆分株测定器官14C同位素活度均呈现饲喂叶＞茎＞前端(RDF)＞后端(RDB)的递降序列;火炬树1～4年生克隆分株前端侧根次生木质部宽度超过后端侧根次生木质部宽度,在于前端侧根形成层分裂活动活跃,次生木质部导管直径和密度大;1年和3年生火炬树克隆分株前端的IAA/GA3比值高于后端的IAA/GA3比值.分析认为:火炬树克隆分株水平侧根直径不对称与光合产物趋前积累、激素水平以及形成层活动等因素密切相关.火炬树克隆分株的茎和前端侧根分别属于优先和次优先生长与光合产物的贮藏中心.

Staghorn Sumac （Rhus typhina ） is an alien tree species. It is a clonal woody plant with the distinguished characteristics, which the front part of the horizontal lateral root in the Staghorn Sumac is much bigger than the back part. In order to analyze the causes of the distinctive asymmetry of the lateral root diameter of the clonal ramets in Staghorn Sumac, samples were taken during the growth period in 2003. Nine individual plants at age of 1 year with their intact underground organs were carefully digged out and planted in the potters for feeding ^14 C isotope. The lateral roots of each individual plants at age from one to three or four were also taken for testing or observing in laboratory. Then the distribution of photosynthetic products in the clonal ramets were tested by means of isotope ^14 C tracer technique, the contents of hormone such as IAA, GA3 and ABA of different organs in Staghorn Sumac were determined and the anatomical structure characteristics were observed. The experimental results showed that： 1） The abundances of isotope ^14 C in different organs of 9 elonal ramets of Staghorn Sumac were ranked as follows ： feeding leaves 〉 stem 〉 the front part of the lateral root 〉 the back part. 2） As the result of the higher density and larger diameter of vessel in the front part（RDF） of the lateral root of the clonal ramets, the abundant nutrition in the central part of the lateral root and the much numerous layer in the cambium, the width of the secondary xylem of the front part in the clonal ramets at age from 1 to 4 years was much larger than that of the back part（RDB）. 3）IAA/GA3 ratio of the front part in the clonal ramet at age of 1 and 3 was much higher than that of the back part. Therefore, it was concluded that the asymmetry of the lateral root diameter between the front part and the back part in Staghorn Sumac clonal ramet would be induced by the nonbalance accumulation of photosynthetic products, which accumulated in the front part of the lateral root of the clonal ramet much more than the back part, and related to the hormone level and the cambium activity closely. The stem of the clonal ramet and its front part of the lateral root would belong to the dominant and subdominant growth and the store center of photosynthetic products respectively.