外源IAA、GA3和ABA影响不同穗型小麦分蘖发生的机制

以山农15和山农8355为材料，研究外源生长素(IAA)、赤霉素(GA₃)、脱落酸(ABA)对小麦分蘖发生的影响及其作用方式。结果显示，外源IAA和GA₃可抑制分蘖的发生，而外源ABA则仅减缓了分蘖发生速率。进一步分析外源激素对分蘖芽生长动态及分蘖节中内源激素变化的影响，发现外源IAA和GA₃完全抑制分蘖芽的生长，而外源ABA明显减缓了分蘖芽的生长速率。外源IAA提高分蘖节中IAA含量和IAA/ZT比，抑制ZT含量的提高；外源GA₃提高分蘖节中IAA含量、IAA/ZT比和ABA/ZT比，抑制ZT含量的提高；外源ABA提高分蘖节中ABA/ZT比，减缓了ZT含量的升高速率。相关性分析显示，分蘖芽的生长与ZT呈显著正相关，与IAA、IAA/ZT比和ABA/ZT比呈显著负相关，与GA₃和ABA呈不显著的负相关。试验结果表明，IAA和ZT在小麦分蘖发生过程中起关键作用，外源激素主要通过影响内源IAA、ZT含量以及IAA/ZT比和ABA/ZT比来影响分蘖芽的生长，进而调控小麦分蘖的发生。

Mechanisms of Tiller Occurrence Affected by Exogenous IAA,GA3, and ABA in Wheat with Different Spike-types

Two winter wheat cultivars, Shannong 15 and Shannong 8355, were used to study the effects of exogenous indole-3-acetic acid (IAA), gibberellic acid 3 (GA₃), and abscisic acid (ABA) on tiller occurrence in wheat and the underlying mechanism. Exogenous IAA and GA₃ inhibited occurrence of wheat tiller, while exogenous ABA reduced the rate of tiller occurrence. Furthermore, exogenous IAA and GA₃ completely inhibited growth of tiller bud, while exogenous ABA significantly slowed the growth rate of tiller bud. The growth of tiller bud was positively correlated with content ofzeatin (ZT), but negatively correlated with IAA content and ratios of IAA/ZT and ABA/ZT. In contrast, the growth of tiller bud had slightly negative correlations with GA₃ and ABA contents. These results suggest that IAA and ZT play a key role in regulating tiller occurrence in wheat, and exogenous hormones regulate the growth of tiller bud through changing contents of IAA and ZT and the ratios of IAA/ZT and ABA/ZT in tiller node.