多效唑调节水稻植株生长的作用机理

多效唑处理水稻植株后使株高降低和分蘖增加,植株体内的GA类物质和IAA含量相应下降,乙烯释放率显著增加;用外源GA_3和氮肥能逆转多效唑的抑制作用而使株高增加,同时GA类物质含量也明显增加。因此,多效唑不仅调节体内的GA类物质含量,还能通过调节IAA含量和乙烯释放率而影响植物生长。

Mechanism of the Action of Multiple-Effect Triazole on Rice Growth

The levels of plant endogenous hormones(GA, IAA and Ethylene)in MET-treated anduntreated rice plants were measured. Sam-ples were collected from cv. Shanyou No. 63(Oryza sativa L. subsp. hsien Ting) grown inpots. Dynamic changes of endogenous gib-berellin-like substance levels in MET-treatedand untreated rice seedlings were shown inFig. 2. Average content of GA-like substancein MET-treated rice seedlings was reduced toonly 8.4% of that of control, Application ofexogenous GA_3 or nitrogen fertilizer could re-verse the growth retarding effect of MET(Fig.3), and, at the same time, increase the GA-like substance content. Levels of endogenousIAA in rice seedlings and stems were also redu-ced dramatically by MET to only 47.5% ofthat of control (Table 2), but application ofexogenous IAA and NAA could not reversethe morphological effects of MET (Table 1).Rate of ethylene evolution in MET-treatedrice seedlings was higher than that in controlby 37.3%. Moreover, the level of an unknowninhibitor separated with TLC from MET-tre-ated rice seedlings was also higher than thatfrom the control (Fig. 5). Therefore, it is suggested that the actionof MET on morphological changes of rice wasnot only through thc regulation of the level ofendogenous GA-like substances, but alsoendogenous levels of IAA, and an unknowninhibitor and ethylene evolution rate etc. Inother words, action of MET on morphologywas effected through the action of severalendogenous plant hormones as diagrammed inthe last paragraph of the paper.