State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100094, China.
*Correspondence author: Tel.: +86-10-68975297; Fax: +86-10-68975297, E-mail: wanfangh@public3.bta.net.cn
1Horticulture and Plant Protection College, Yangzhou University, Yangzhou, 225009, China.
We investigated the mechanism of two allelochemicals: DTD [4,7-dimethyl-1-(propan-2-ylidene)-1,4,4a, 8a-tetrahydronaphthalene-2, 6(1H, 7H)-dione] and HHO [6-hydroxyl-5-isopropyl-3, 8–dimethyl-4a, 5, 6, 7, 8, 8a-hexahydronaphthalen-2(1H)-one] isolated from Ageratina adenophora Sprengel weed, on the content of 3 endogenous hormones [abscisic acid (ABA), indole-3-acetic acid (IAA), and zeatin riboside (ZR),] in roots of upland rice seedlings. Hydroponic experiments were conducted on upland rice ‘Han 277’, DTD or HHO were applied at 3 concentrations (0.5, 1.0 and 1.5 mM) for 12, 24, 48 and 96 h on the test rice plants. The DTD at higher concentration, significantly increased the ABA contents in the roots of rice seedlings, but decreased sharply 96 h after treatment. HHO also significantly enhanced the ABA contents 48 and 96 h after application over the control. But the application of DTD or HHO decreased the IAA content in rice roots and was “concentration dependent” as compared to control. ZR content in DTD or HHO treated rice seedlings roots exhibited similar profiles to IAA content. The IAA/ABA as well as ZR/ABA ratios decreased quantitatively in response to higher concentrations and duration of exposure than control. These results suggested that the endogenous hormones might have separate as well as interactive effects on how rice seedlings respond and adapt to DTD or HHO stress under natural environments.
Abscisic acid, Ageratina adenophora, allelochemicals, indole-3-acetic acid, upland rice, zeatin riboside
