Indole-3-acetic acid producing bacteria and its application on the growth of rice

摘要

Phytohormone is an important compound regulating specific plant growth. Auxin and cytokines can be obtained in the form of synthetic compounds or produced by organisms and used to increase crop production. Various types of plant growth-promoting bacteria produce various types of phytohormone. Indole-3-Acetic Acid is a key hormone for many aspects of plant growth that can regulate many physiological processes. The objective of the study was to obtain IAA (auxin) producing bacteria and its application on rice growth. Nineteenth isolates from Biogen Culture Collection were screened indolic compound production by spectrophotometer. Moreover, all isolates were selected in greenhouse to monitor the effect of bacterial application on the growth of rice plant. After that, all isolates were identified based on 16S rRNA. The result of quantitative analysis of IAA production from 17 bacterial isolates showed that Enterobacter ludwigii FB Endo 135 produced the highest IAA (43.8 mg·L~(-1)), while the smallest IAA concentration produced by Azm 1.7.2.12 (7.63 mg·L~(-1)). Application bacterial isolates on rice plant growth showed that there was a significant effect of bacterial application on rice plant height. There was a 6.7 % increase in plant height by Azm 5.7.5.1 with an IAA production capability of 12.18 mg·L~(-1) compared with no bacterial inoculation Analysis to dry weight of rice grain showed that there was a significant effect of IAA producing bacteria. The dry weight of rice grain with FB 26 showed the effect of significant difference of 99.54 % by weight 30.41 g compared with negative control. Based on the effect of IAA producing bacteria on the growth of rice plants, there were some potential bacteria. Pseudomonas fragi, Bacillus cereus, and Rhizobium that can promote plant height, while Bacillus aerius, Pseudomonas fragi and Bacillus cereus promote dry weight of rice grain, and Bacillus amyloliquenfaciens promote roots dry weight.