ABSTRACT
The effect of indolebutyric acid (IBA) and gibberellic acid (GA3), to alleviate the organochlorine phytotoxicity were studied in Brassica chinensis. Presence of organochlorine decreased Brassica chinensis seedlings growth in contaminated alkaline soil. One mg l-1 IBA could enhance 14 and 26% shoot and root length of B. chinensis seedlings grown at 40 mg kg-1 lindane contaminated soil, respectively. Ten mg l-1 IBA also increased 80 and 40% root fresh weight of seedling grown in 40 mg kg-1 lindane and alpha-endosulfan contaminated soils, respectively. However, IBA had no effect on shoot and root length of seedlings grown in endosulfan contaminated soil. On the other hand, 10 mg l-1 GA3 only increased 80% of shoot and root fresh weigh of B. chinensis in 40 mg kg-1 endosulfan contaminated soil. External auxin addition could increase B. chinensis growth in lindane more than endosulfan contaminated soil. External gibberellin was less effective than external auxin to increase B. chinensis growth in organochlorine contaminated soil. There is possibility that auxin could decrease organochlorine phytotoxicity in plants and hence can be useful for organochlorine phytoremediation.
ABSTRACT
A study was undertaken to assess if corn plant (Zea may L.) may be able to enhance the degradation of phenanthrene and pyrene in acidic soil inoculated with a bacterial strain (Pseudomonas putida MUB1) capable of degrading polycyclic aromatic hydrocarbons (PAHs). Planting with corn, inoculating with MUB1, or a combination of the two were found to promote the degradation of phenanthrene and pyrene in acidic soil at different rates. In the presence of corn plants, the rates of phenanthrene and pyrene removal were 41.7 and 38.8% in the first 10 days, while the rates were 58.8 and 53.6%, respectively, in the treatment which received MUB1 only. After 60 days, the corn + MUB1 treatment led to the greatest reduction in both phenanthrene and pyrene biodegradation (89 and 88.2%, respectively). In control autoclaved soil, the rates of phenanthrene and pyrene removal were 14.2 and 28.7%, respectively, while in non-autoclaved soil, the rates were 68.7 and 53.2%, respectively. These results show that corn, which was previously shown to grow well in PAH-contaminated acidic soil, also can enhance PAH degradation in such soil. Inoculation with a known PAH degrader further enhanced PAH degradation in the presence of corn.