Abstract: Six tall and dwarf near isogenic lines derived from a dominant semi-dwarfing mutant were studied in plant height traits and sensitivity to GA 3 . The internode elongation was inhibited by the dominant semi-dwarfing gene. The lengths from the basal internode to the uppermost internode and the panicle length in dwarf near isogenic lines were 97.2%,53.3%,65.1%,61.9% and 94.7% of those in the tall ones, respectively. Compared with wild type Y98148, dwarf mutant Y98149 was much more sensitive to GA 3 at both the seedling and adult stages, and showed lower endogenic GA 3 content in plant, with about 78% of the wild one.

Key words: semi-dwarfing gene, near isogenic lines, sensitivity, gibberellin, rice

摘要： 对具有显性半矮秆基因的6对高矮秆近等基因系的株高表达特性进行了比较。水稻显性半矮秆基因抑制了茎秆节间的伸长，矮秆系倒4～5、3、2、1节及穗长分别为高秆系的97.2%、53.3%、65.1%、61.9%和94.7%。通过对Y98149（突变体）和Y98148（野生型）在苗期和成株期对GA3反应的研究，发现Y98149较Y98148对外源赤霉素更敏感；内源赤霉素测定结果显示显性半矮秆突变体内源赤霉素含量较低，是野生型的78%。

关键词: 半矮秆基因, 近等基因系, 敏感性, 赤霉素