Effect of Plant Growth Regulators on Growth of Rice Tiller Bud and Changes of Endogenous Hormones

The objectives of this study were to investigate the changes in plant hormones during tiller bud growing in rice (Oryza sativa L.) and the mechanism that underlies the effect of hormonal regulation on tiller bud growth. Rice cultivars Yangdao 6 (indica) and Nanjing 44 (japonica) were used to investigate the effects of exogenous abscisic acid (ABA, 50 mg L−1), gibberellic acid 3 (GA3, 50 mg L−1), and α-naphthalene acetic acid (NAA, 50 mg L−1) on tiller bud outgrowth and the changes of endogenous hormones. After foliar spray of the exogenous hormones, the tiller bud growth was completely inhibited in treatments of GA3 and NAA applies; but exogenous ABA application slowed down the growth rate of tiller bud. Both exogenous GA3 and NAA increased the ABA contents in tiller node and tiller bud and decreased the zeatin + zeatin riboside (Z+ZR) contents. Exogenous GA3 increased the IAA content in tiller node; besides, the variation of IAA and Z+ZR occurred earlier than that of ABA. Suggestively, these 3 endogenous hormones are closely associated with tiller bud growth, of which only IAA and Z+ZR play key roles, although ABA can affect the growth velocity of tiller bud. Exogenous hormones regulate tiller bud growth through changing the contents of endogenous ABA, IAA, and Z+ZR in rice plant.

摘 要以扬稻6号和南粳44为材料, 研究了外源ABA、GA3和NAA对水稻分蘖芽生长的影响及其与内源激素的关系。结果表明, 外源GA3和NAA可以完全抑制分蘖芽的生长, 而外源ABA只是减缓了分蘖芽的生长速率而没有完全抑制其生长。外源GA3和NAA均提高了分蘖节和分蘖芽中ABA含量, 抑制了分蘖节和分蘖芽中Z+ZR含量的提高, 而且外源GA3还提高了分蘖节中IAA含量, 另外, IAA和Z+ZR含量的变化早于ABA含量的变化。分析试验结果表明, IAA、ABA和Z+ZR三种内源激素与水稻分蘖芽生长密切相关, IAA和Z+ZR是生长的主要调控因素, 而ABA不是, 外界因素对分蘖芽生长的调控主要通过调控这3种激素实现。