X.Z. Yu; M.R. Lu
Abstract
Hydroponic experiments were performed to exam the dynamic change of endogenous proline in rice seedlings exposed to potassium chromate chromium (VI) or chromium nitrate chromium (III). Although accumulation of both chromium species in rice seedlings was obvious, more chromium was detected in plant tissues ...
Read More
Hydroponic experiments were performed to exam the dynamic change of endogenous proline in rice seedlings exposed to potassium chromate chromium (VI) or chromium nitrate chromium (III). Although accumulation of both chromium species in rice seedlings was obvious, more chromium was detected in plant tissues of rice seedlings exposed to chromium (III) than those in chromium (VI), majority being in roots rather than shoots. Results also showed that the accumulation capacity of chromium by rice seedlings was positively correlated to chromium concentrations supplied in both chromium variants and the accumulation curve depicted an exponential trend in both chromium treatments over the entire period of exposure. Proline assays showed that both chromium variants induced the change of endogenous proline in shoots and roots of rice seedlings. Chromium (VI) of 12.8 mg/L increased proline content significantly (p<0.05) compared to control, while the effect of chromium (III) on proline content was more evident at 30.0 mg/L (p<0.05). The results collected here suggest that both chromium variants are able to cause the change of endogenous proline in rice seedlings, but the response was found to be different between the two chromium treatments.
X.Z. Yu; Y.X. Feng; D.M. Yue
Abstract
Methylene blue is widely used in various industrial branches. Due to insufficient treatment, its occurrence in wastewater is frequently detected, which may result in serious environment problems to aquatic organisms. Hydroponic experiments were conducted with rice seedlings (Oryza sativa L. cv. XZX 45) ...
Read More
Methylene blue is widely used in various industrial branches. Due to insufficient treatment, its occurrence in wastewater is frequently detected, which may result in serious environment problems to aquatic organisms. Hydroponic experiments were conducted with rice seedlings (Oryza sativa L. cv. XZX 45) exposed to methylene blue to determine the effective concentration using relative growth rate and water use efficiency as response endpoints. Results showed that acute toxicity of methylene blue to rice seedlings was evident. Although a linear decrease in relative growth rate and water use efficiency was observed in rice seedlings with increasing methylene blue concentrations, relative growth rate of rice seedlings was more sensitive to change of methylene blue than water use efficiency. Using non-linear regression, EC-48 h values for 10%, 20% and 50% inhibition of the relative growth rate were estimated to be 1.54, 3.22 and 10.13 mg MB/L for rice seedlings exposed to methylene blue, respectively, while smaller EC were obtained for 96 h exposure. In conclusion, the toxic response of young rice seedlings to methylene blue is obvious and inhibitory effects are highly dependent on response endpoints and the duration of exposure period.