中文摘要：

采用水培实验，在水稻苗期研究外源添加不同浓度生长素（3-吲哚乙酸，IAA）对水稻根系（根长、根重）、地上部（株高、地上部重量）生长和叶绿素含量的影响。结果表明，不同浓度IAA处理水稻1d-5d，对水稻苗期的生长无明显影响。处理时间延长至10d，1μMIAA处理水稻根长显著增加（p〈0．05），增加了41．1％，对株高、根重和地上部重量无明显影响。随IAA浓度的升高，对其影响表现出一定的差异。与对照相比，10μM、25μM和100μMIAA处理根重显著增加（p〈0．05），分别增加了39．1％、25．9％和17．8％；25μM-100μMIAA处理使株高和地上部重量显著降低，降幅分别在16．0％-20．7％和20．0％-36．7％之间，导致其根冠比随IAA浓度增加而增大。与对照相比，外源施加IAA（1μM-75μM）处理使水稻叶绿素a,b和总含量均显著增加（p〈0．05），增幅均在30％以上，以10μM对叶绿素含量的影响最大。因此，外源施加适宜浓度的IAA可以促进水稻的生长和叶绿素含量的提高，促进植物光合效率，提高水稻产量。

英文摘要：

A hydroponic experiment was conducted to study the effects of the exogenous auxin （3 -indole acetic acid, IAA） on rice roots （root length, root weight）, shoot growth （height and biomass） and chlorophyll content in the rice seedling stag~ The results showed that the root growth in rice seedling was no significant difference when treated with different concentrations oflAA from ld to 5d When treated for 10d, root length of rice for the treatment of 1μM IAA in creased by 41.1% （p〈0.05）, while plant height, root and shoot weights were not significantly affected; root weight for the treatments of 100M, 251J M and 1001JM IAA increased by 39.1%, 25.9% and 17.8% （p 〈0.05）, respectively; plant heights and shoot weights reduced significantly from a rate of 16.0% to 20.7%, and from 20.0% to 36.7% with increasing IAA concentration from 25μM to 100μ M IAA, respectively, as compared with CK. As a result, the ratios of root to shoot increased with IAA concentration increases. Moreover, contents of chlorophyll a, b and total chlorophyll for treatments with IAA （1μM-75μM） increased by more than 30% （p 〈0.05） compared with the control. Therefore, applying IAA with a suitable concentration in rice seedling stage can promote rice growth and increase chlorophyll content, which is beneficial to promote photosynthesis efficiency and improve rice yield.