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Jing Y.-X.,South China Normal University | Liu R.-X.,South China Normal University | Xiao L.,South China Normal University | Li G.-L.,South China Normal University | Yang D.-J.,Guangzhou Research Academy of Environmental Protection
Wetland Science | Year: 2011

Periodic flooding of trees in tropical floodplains and reservoirs where water levels fluctuate is a common phenomenon. The alternating terrestrial and aquatic periods with advancing and receding floods poses a variety of constraints to the plants growing in this habitat. If flooding is recurrent before the plants recover from previous flooding, injuries will accumulate and serious damage may occur. Therefore, when assessing plant resistance to flooding, it is important to consider the ability of plants to recover from transient waterlogging. The success of tree planting on floodplain and reservoir depends not only on the tree's tolerance to submersion, but also on their subsequent recovery. Previous studies on physiological and growth responses of tree species to flooding have mostly focused on the responses to continuous flooding, but little is known about the responses to subsequent recovery after the removal of the flooding stress. Recovery effects of gas exchange, chlorophyll fluorescence and membrane permeability of Melaleuca alternifolia seedlings, a tall shrub species used in floodplain and reservoir forest restoration in southern China, were studied after submersion. Throughout a 30-day submersion and another 70-day recovery period, the survival rates of M. alternifolia seedlings were 100%. After 30-day submersion, pronounced decrease of chlorophyll content, net photosynthetic rate (Pn), stomatal conductance(Gs), transpiration rate(Tr), the maximum quantum efficiency of the photosystem II (Fv/Fm), photochemical quenching coefficient (qP), and increase of non-photochemical quenching (NPQ), membrane permeability in the period after submersion, gradual increase of chlorophyll content, Pn, Gs, Tr, Fv/Fm, qP, and decrease of NPQ, membrane permeability in the recovered seedlings were found, and the above parameters in the recovered seedlings reached the levels similar to the control after 60-day recovery. Our study demonstrated that M. alternifolia seedlings is tolerant of flooding, and seedlings of this species would be suitable for afforestation in river banks and reservoir banks exposed to intermittent flooding. Source


Jing Y.X.,South China Normal University | Yan J.L.,South China Normal University | He H.D.,South China Normal University | Yang D.J.,Guangzhou Research Academy of Environmental Protection | And 5 more authors.
International Journal of Phytoremediation | Year: 2014

Microbe-enhanced phytoremediation has been considered as a promising measure for the remediation of metal-contaminated soils. In this study, two bacterial strains JYX7 and JYX10 were isolated from rhizosphere soils of Polygonum pubescens grown in metal-polluted soil and identified as of Enterobacter sp. and Klebsiella sp. based on 16S rDNA sequences, respectively. JYX7 and JYX10 showed high Cd, Pb and Zn tolerance and increased water-soluble Cd, Pb and Zn concentrations in culture solution and metal-added soils. Two isolates produced plant growth-promoting substances such as indole acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and solubilized inorganic phosphate. Based upon their ability in metal tolerance and solubilization, two isolates were further studied for their effects on growth and accumulation of Cd, Pb, and Zn in Brassica napus (rape) by pot experiments. Rapes inoculated with JYX7 and JYX10 had significantly higher dry weights, concentrations and uptakes of Cd, Pb, Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg-1), Pb (200 mg kg-1) or Zn (200 mg kg-1). The present results demonstrated that JYX7 and JYX10 are valuable microorganism, which can improve the efficiency of phytoremediation in soils polluted by Cd, Pb, and Zn. © 2014 Copyright Taylor and Francis Group, LLC. Source


Jing Y.X.,South China Normal University | Li G.L.,South China Normal University | Gu B.H.,University of Florida | Yang D.J.,Guangzhou Research Academy of Environmental Protection | And 3 more authors.
Photosynthetica | Year: 2010

Periodic flooding of trees in tropical floodplains and reservoirs where water levels fluctuate is a common phenomenon. The effects of flooding and subsequent recovery on gas exchange, chlorophyll fluorescence and growth responses of Melaleuca alternifolia seedlings, a tall shrub species used in floodplain and reservoir forest restoration in southern China, were studied during a grow season (from March to December in 2007). M. alternifolia seedlings were flooded for 180 days, drained and left to recover for another 60 days. Survival rates of the seedlings were 100% during the 180-day flooding period. Chlorophyll (Chl) content, net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) of the flooded seedlings were all significantly lower than those of the control. Significant reductions of photochemical quenching coefficient (qp) and increases of nonphotochemical quenching (NPQ) in the flooded seedlings were observed. However, there were no significant differences in the maximal quantum yield of PSII photochemistry (Fv/Fm) between treatments. All seedlings survived during the two-month recovery period after the flooded treatment was drained, and the biomass and height of the recovered seedlings approached those of the control at the end of the experiment. During the first-month recovery period, Chl content, PN, gs and E in the recovered seedlings were all obviously low, then increased gradually and rose to the levels similar to the control by the end of the experiment. Quenching analysis revealed significant reductions of qp and increments of NPQ in the recovered seedlings at the beginning of draining, and a nearly complete recovery for both parameters by the end of the experiment. However, Fv/Fm of the recovered seedlings did not differ significantly from the control during the recovery period. Our study demonstrated that M. alternifolia seedlings can survive and grow through 180 days of flooding with a subsequent 60-day recovery period in drained conditions, indicating that seedlings of this species would be suitable for afforestation in areas exposed to intermittent flooding. © Springer Science+Business Media B.V. 2010. Source


Liu R.,South China Normal University | Jing Y.,South China Normal University | Xiao L.,South China Normal University | Li G.,South China Normal University | And 2 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010

The effects of flooding depth on gas exchange, chlorophyll fluorescence and growth of Melaleuca alternifolia seedlings were studied. Seedlings were subjected to two hydrological treatments: shallow flooding and deep flooding with water level at 5cm and 20cm above the soil surface, respectively. Results indicated that the effect of flooding on Melaleuca alternifolia was elevated with the increase in the flooding depth. After 270 days of flooding, the height and biomass of the shallow-flooded and deep-flooded seedlings were significantly lower, accounting for 90. 86%, 64. 58% and 74. 52%, 36.46% of the control, respectively. Chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate of the shallow-flooded seedlings were all slightly lower, accounting for 95. 39%, 94. 26%, 90. 02% and 88. 94% of the control, respectively. However, these parameters in the deep-flooded seedlings were all significantly lower within 180 days of flooding, accounting for 79. 44% ^73. 54% ^61. 79% and 71. 46% of the control, respectively, and then approached gradually to those of the control. There were no differences in the maximum quantum efficiency of the photosystem II (Fv/Fm) between the shallow-flooded and control seedlings. Fv/Fm of the deep-flooded seedlings wasslightly lower within 150 days of flooding, and then recovered to the levels of the control. A slight reduction of photochemical quenching coefficient (qP) and an increase of non-photochemical quenching (NPQ) in the shallow-flooded seedlings were observed, accounting for 96. 63% and 105. 66% of the control, respectively. However, a pronounced decrease of qP and an increase of NPQ in the deep-flooded seedlings were found within 120 days of flooding, accounting for 94.51% and 126.66% of the control, respectively, and then approached gradually to those of the control. Moreover, M. alternifolia developed aerenchyma and adventitious roots during inundation, with root porosity in the flooded seedlings much higher than that of the control. Source


Lu G.,South China Normal University | He H.,South China Normal University | Yang D.,Guangzhou Research Academy of Environmental Protection | Cai X.,South China Institute of Environmental Sciences | Jing Y.,South China Normal University
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

There are ongoing debates about cutting effects on the growth and wastewater purification of plants in constructed wetlands. This experiment was carried out in the Biological Park, South China Normal University from July 2010 to January 2011. Constructed wetlands (2m×2m×0. 6m) were grown with Cyperus alternifolius to assess cutting effects on growth and wastewater purification. The growth rate of C. alternifolius remained high for the treatment (cutting) group during the entire experiment period but was low for the control (no cutting) group after November 2010. At the end of the experiment, accumulated aboveground biomass, nitrogen and phosphorus contents, and new tillers from July 2010 to January 2011 in the treatment group were higher than those in the control group, and C. alternifolius showed overcompensation growth. The chlorophyll content, net photosynthetic rate, transpiration rate and stomatal conductance in the treatment group were evidently higher than those of the control group. The average removal rates of TP, TN, NH4 -N and NO3 -N in the treatment and the control group were 77%, 84%, 64%, 72% and 65%, 67%, 55%, 63%, respectively, which were significantly higher in the treatment than the control group. The average removal rates of CODcr and BOD5 in treatment and the control group were 58%, 79% and 54%, 76%, respectively, which were not significantly different. These findings suggested that a positive effect of cutting on growth and wastewater purification of C. alternifolius in constructed wetlands, which may provide insightful information on the management of constructed wetlands. Source

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