Morphological characteristics and physiological indexes of Clerodendrum trichotomum with waterlogging

Key words: 
• botany /
• Clerodendrum trichotomum /
• waterlogging /
• morphological characteristics /
• physiological indexes

Abstract: To determine resistance ablity of Clerodendrum trichotomum to waterlogging stress，taking small bowl in large bowl as method，the experiment set five watelogging levels （water height treatments of 1/4，1/2，and 2/3 of the soil thickness；level to the surface； and 5 cm above the surface）. Each processing had 10 plants and taking the day-to-day management plants as control group. One-year-old cuttings of Clerodendrum trichotomum were used with five watelogging levels to study their morphological characteristics and physiological indexes. Results showed that when the water level was 1/4 or 1/2 of the soil thickness，there were no significant changes in morphological characteristics and physiological indexes compared with the control，but at 2/3 of the soil thickness，after 6 d of waterlogging stress and with an increase of stress time，the leaves wrinkled，curled，wilted，and drooped compared with the control，and at 12 d of stress relative water content，proline content，SOD activities respectively were significantly decreased to 0.55 times，0.59 times，0.80 times that of the control；relative conductivities，MDA content，soluble sugar content，soluble protein content respectively were significantly increased to 2.71 times，1.76 times，21.93 times，2.03 times that of the control，and then the plants died. When the water level was at the surface of the soil or 5 cm above it，plants wilted because of rapid loss of water which could be proved by the significantly decreased of relative water content，and then died after 8 d of stress. With an increase in water level and stress time，compared with the control，the proline content，soluble sugar content，MDA content，and relative conductivity significantly increased；relative water content and SOD activity significantly decreased; and soluble protein content and chlorophyll content were decreasing first then increasing trend. We could conclude that plants exhibits strong osmotic adjustment capacity，mainly by significantly increasing the proline and soluble sugar content to adapt to the waterlogged environment. Plants have a strong ability to maintain the stability of morphological characteristics and physiological indexes to tolerate water-stress，but only when the water level is up to 1/2 of the soil thickness. Flood tolerance is poor，because when the water level was at the surface of the soil or 5 cm above it，plants died after 8 d of waterlogging stress. In the configuration of the plant，they can be planted in the lake，river，pool springs，streams and other relatively high moisture content of the soil，which enrich their usages as an ornamental plant.［Ch，8 fig. 21 ref.］